JP2010100095A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of suppressing partial wear and prolonging the lifetime of the tire. <P>SOLUTION: The pneumatic tire comprises a belt layer 11 provided on the outer side in the tire radial direction of a carcass layer forming a skeleton of the pneumatic tire 1, a belt reinforcing layer 13 which covers an end in the tread width direction of the belt layer 11 inward of the tire radial direction, and is arranged separately in the tread width direction, and a tread part 9 which is provided on the outer side in the tire radial direction of the belt layer 11 and the belt reinforcing layer 13 while a land part 17 is formed by a plurality of circumferential grooves 15 extending in the tire circumferential direction. The width (W1) of an end land part which is the width of an end land part 17A in the tread width direction is 100-200% to a center land width (W2) which is the width of a center land part 17B in the tread width direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire including at least a tread portion in which a plurality of land portions are formed by a plurality of circumferential grooves extending in the tire circumferential direction.

Conventionally, a cord having excellent rigidity is used for a carcass cord used for a carcass layer forming a skeleton of a pneumatic tire and a belt cord used for a belt layer for reinforcing a tread portion in contact with a road surface. A pneumatic tire to be improved is known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-227427 (FIG. 1)

  However, the conventional pneumatic tire described above has the following problems. That is, at the time of high speed running, the tread end portion side where the belt layer does not exist is inferior in rigidity to the tread central portion, so that the air filled in the pneumatic tire expands outward in the tire radial direction. It is easy to do (so-called diameter growth rate is high). For this reason, with the occurrence of uneven wear, the tire life has been shortened.

  In particular, depending on the setting in which a pneumatic tire is mounted on the vehicle (for example, a negative camber in which the upper part of the tire is inclined toward the inside of the vehicle body), the wear on the inner side when the vehicle is mounted on the tire equator line, so-called uneven wear is further accelerated. End up.

  Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a pneumatic tire that can suppress uneven wear and extend the life of the tire.

  In order to solve the above situation, the present invention has the following features. First, the invention according to the first aspect of the present invention includes a belt layer provided on the outer side in the tire radial direction of the carcass layer forming the skeleton of the pneumatic tire, and an end portion in the tread width direction of the belt layer on the inner side in the tire radial direction. A land portion is formed by a belt reinforcing layer that is covered and spaced apart in the tread width direction, and a plurality of circumferential grooves extending in the tire circumferential direction that are provided outside the belt layer and the belt reinforcing layer in the tire radial direction. The end land portion width (W1), which is the width in the tread width direction of the end land portion located at the tread end portion of the land portion, is located at the tread center portion of the land portion. The gist is that it is 100 to 200% with respect to the central land portion width (W2) which is the width of the central land portion in the tread width direction.

  According to such a feature, the belt reinforcing layer covers the end of the belt layer, and the end land portion width (W1) is 100 to 200% with respect to the central land portion width (W2). The rigidity on the part side can be improved, and the expansion of the tire in the radial direction of the tire (hereinafter referred to as the diameter growth rate) can be suppressed by the air filled in the pneumatic tire. As a result, uneven wear can be suppressed, and the tire life can be extended.

  Another feature is summarized in that the belt reinforcing layer is composed of a belt cord and rubber, and the belt cord is a composite cord in which a low elastic cord and a high elastic cord are twisted together.

  According to this feature, since the belt cord is a composite cord, the diameter growth rate can be suppressed as compared with the case where only the low elastic cord is used for the belt cord, and therefore, uneven wear can be further suppressed. .

  Another feature is summarized in that the low elastic cord is a nylon cord and the high elastic cord is an aramid cord.

  Another feature is that a plurality of width direction grooves extending in the tread width direction are formed in the intermediate land portion and the end land portion formed between the end land portion and the central land portion. The number of end blocks defined by the circumferential grooves and the width direction grooves in the portion is 0.5 times or more than the number of intermediate blocks defined by the circumferential grooves and the width direction grooves in the intermediate land portion. It is a summary.

  According to this feature, when the number of end blocks is 0.5 times or more the number of intermediate blocks, the diameter growth rate can be further suppressed, and uneven wear can be further suppressed.

  Another feature is that a plurality of width direction grooves extending in the tread width direction are formed in the intermediate land portion and the end land portion formed between the end land portion and the central land portion. The number of end blocks defined by the circumferential grooves and the width direction grooves in the portion is twice the number of intermediate blocks defined by the circumferential grooves and the width direction grooves in the intermediate land portion. The gist.

  According to this feature, the number of end blocks is twice the number of intermediate blocks, whereby the diameter growth rate can be further suppressed and uneven wear can be further suppressed.

  Another feature is that the inner end land portion width (W1-IN), which is the width in the tread width direction of the end land portion located on the inner side when the vehicle is mounted on the tire equator line, is the vehicle with respect to the tire equator line. The gist is that it is wider than the outer end land portion width (W1-OUT), which is the width in the tread width direction of the end land portion located outside.

  According to this feature, the inner end land portion width (W1-IN) is wider than the outer end portion land portion width (W1-OUT), so that the tire upper portion is set as a negative camber that is inclined inward of the vehicle body. Even if it is a case, since the abrasion of the edge part land part located inside at the time of vehicle mounting | wearing can be suppressed, generation | occurrence | production of partial wear can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can suppress uneven wear and can extend a tire life can be provided.

  Next, an example of a pneumatic tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

(Composition of pneumatic tire)
First, the configuration of the pneumatic tire according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view in the tread width direction showing a pneumatic tire according to the present embodiment, and FIG. 2 shows a carcass layer, a belt layer, and a belt reinforcing layer constituting the pneumatic tire according to the present embodiment. It is a top view.

  As shown in FIG. 1, the pneumatic tire 1 includes a pair of bead portions 3 including at least a bead core 3a and a bead filler 3b, and a carcass layer 5 that forms a skeleton of the pneumatic tire 1 and is turned back by the bead core 3a. ing.

  On the inner side of the carcass layer 5, an inner liner 7 which is a highly airtight rubber layer corresponding to a tube is provided. A belt layer 11 that reinforces the tread portion 9 that is in contact with the road surface is provided on the outer side in the tire radial direction of the carcass layer 5.

  A belt reinforcing layer 13 that covers the tread width direction end portion 11a of the belt layer 11 toward the inner side in the tire radial direction and is spaced apart in the tread width direction is provided on the outer side of the belt layer 11 in the tire radial direction. ing.

  Specifically, as shown in FIG. 2, the belt reinforcing layer 13 is composed of a belt cord 13A and rubber 13B. The belt cord 13A is preferably a composite cord in which a low elastic cord and a high elastic cord are twisted together. In particular, the low elastic cord is preferably nylon cord or polyethylene terephthalate resin (PET cord), and the high elastic cord is preferably aramid cord or polyethylene naphthalate resin cord (PEN cord).

  The reinforcing layer width (RW), which is the width of the belt reinforcing layer 13 in the tread width direction, is the maximum width in the tread width direction in which the tread portion 9 is in contact with the road surface with reference to the tread width direction end portion 11a of the belt layer 11. It is preferably 5 to 30% with respect to a certain tread ground contact width (TW).

  If the reinforcing layer width (RW) is smaller than 5% with respect to the tread ground contact width (TW), it is difficult to improve the rigidity on the tread end portion S side, and the air filled in the pneumatic tire 1 is filled. Therefore, expansion to the outside in the tire radial direction (hereinafter referred to as a diameter growth rate) may not be suppressed. On the other hand, if the reinforcing layer width (RW) is larger than 30% with respect to the tread ground contact width (TW), it is difficult to change the rigidity of the tread central portion C and the tread end portion S, and as a result, the tread end Wear on the part S side is promoted, and uneven wear may not be suppressed.

  Thus, in the tread central portion C, one belt layer 11 is provided except for the carcass layer 5. In addition, on the tread end portion S side, two layers including a single belt layer 11 and a single belt reinforcing layer 13 are provided except for the carcass layer 5.

  In addition, the tread center part C shows the area | region of 10 to 15% with respect to a tread contact width (TW) on the basis of the tire equator line CL. Further, the tread end portion S indicates a region of 10 to 30% with respect to the tread ground contact width (TW) from both ends of the tread ground contact width (TW). In addition, the tread intermediate part M mentioned later shows the area | region between the tread center part C and the tread edge part S. FIG.

(Configuration of tread pattern)
Next, the configuration of the tread pattern will be described with reference to FIG. FIG. 3 is a development view showing a tread pattern of the pneumatic tire according to the present embodiment.

  As shown in FIG. 3, land portions 17 are formed in the tread portion 9 of the pneumatic tire 1 by a plurality of circumferential grooves 15 extending in the tire circumferential direction.

  The end land portion width (W1), which is the width in the tread width direction of the end land portion 17A located at the tread end portion S of the land portion 17, is the central land located at the tread central portion C of the land portion 17. It is 100-200% with respect to the central land part width (W2) which is the width | variety with respect to the tread width direction of the part 17B.

  When the end land width (W1) is smaller than 100% with respect to the central land width (W2), the portion where the thickness of the tread portion 9 is lost as compared with the land portion 17 increases. (The groove area increases too much), and braking and drivability deteriorate. On the other hand, if the end land portion width (W1) is larger than 200% with respect to the central land portion width (W2), the groove area is excessively reduced, and the drainage performance and the like are deteriorated.

  Further, the inner end land portion width (W1-IN), which is the width in the tread width direction of the end portion land portion 17A located on the inner side with respect to the tire equator line CL, is the vehicle with respect to the tire equator line CL. It is preferably wider than the outer end land portion width (W1-OUT), which is the width in the tread width direction of the end land portion 17A located outside at the time of mounting.

  When the inner end land portion width (W1-IN) is narrower than the outer end land portion width (W1-OUT), the vehicle is mounted when the upper portion of the tire is set to a negative camber that is inclined toward the inner side of the vehicle body. The wear of the end land portion 17A located on the inner side is accelerated, and the occurrence of uneven wear may not be suppressed.

  Further, the intermediate land portion width (W3) which is located in the tread intermediate portion M, that is, the width in the tread width direction of the intermediate land portion 17C formed between the end land portion 17A and the central land portion 17B, It is preferably narrower than the end land portion width (W1) and wider than the central land portion width (W2).

  Further, the inner central land portion width (W3-IN), which is the width in the tread width direction of the central land portion 17B located on the inner side when the vehicle is mounted with respect to the tire equator line CL, is the width when the vehicle is mounted with respect to the tire equator line CL. It is preferably wider than the outer central land portion width (W3-OUT), which is the width of the central land portion 17B located outside in the tread width direction.

  If the inner central land portion width (W3-IN) is narrower than the outer central land portion width (W3-OUT), the inner side when the vehicle is mounted when the upper portion of the tire is set to a negative camber inclined toward the inner side of the vehicle body. Wear of the end land portion 17A located in the region is accelerated, and uneven wear may not be suppressed.

  Here, a plurality of width direction grooves 19 extending obliquely with respect to the tread width direction are formed in the intermediate land portion 17C and the end land portion 17A.

  The number of end blocks 21 defined by the circumferential grooves 15 and the width direction grooves 19 in the end land portion 17A is equal to the number of end blocks 21 defined by the circumferential grooves 15 and the width direction grooves 19 in the intermediate land portion 17C. It is preferably 0.5 times or more the number of blocks 23. In particular, the number of end blocks 21 is preferably twice the number of intermediate blocks 23.

  If the number of end blocks 21 is less than 0.5 times the number of intermediate blocks 23, the rigidity of the end blocks 21 becomes too small compared to the rigidity of the intermediate blocks 23, which promotes uneven wear. May end up.

(Action / Effect)
According to the pneumatic tire 1 according to the present embodiment described above, the belt reinforcing layer 13 covers the end portion of the belt layer 11, and the end land portion width (W1) is larger than the central land portion width (W2). By being 100 to 200%, the rigidity on the tread end portion S side can be improved and the diameter growth rate can be suppressed. As a result, uneven wear can be suppressed, and the tire life can be extended.

  Further, since the belt cord 13A is a composite cord in which a low elastic cord (particularly nylon cord) and a high elastic cord (particularly an aramid cord) are twisted together, only the low elastic cord is used for the belt cord 13A. In comparison, since the diameter growth rate can be suppressed, uneven wear can be further suppressed.

  Specifically, since the pneumatic tire 1 is rounded in the tire circumferential direction and also in the tread width direction, the tread portion 9 (the belt layer 11 and the belt) is considered in consideration of wear resistance and steering stability. The strength and elongation of the reinforcing layer 13) must be compatible.

  For this reason, as for the belt cord 13A used for the belt reinforcement layer 13, it was examined whether or not a nylon cord, an aramid cord, and a composite cord obtained by twisting a nylon cord and an aramid cord are optimal. FIG. 4 is a graph for comparing the characteristics (strength / stretching degree) of the respective cords.

  As shown in FIG. 4, the composite cord is superior in strength to the nylon cord, but is inferior in elongation. On the other hand, it can be seen that the composite cord has a higher degree of elongation than the aramid cord, but is inferior in strength. That is, the composite cord can achieve both strength and extension.

  When the inflection point between the strength and the degree of elongation is less than 2% when the composite cord reaches from the low elastic region where the elastic modulus is low to the high elastic region where the elastic modulus is high, the binding force of the tread central portion C is reduced. The rigidity of the belt reinforcing layer 13 (that is, the rigidity on the tread end portion S side) is not improved, and the diameter growth rate cannot be suppressed. Conversely, if the inflection point of the composite cord is greater than 7%, the tread central portion C will come out before reaching the high elastic range, and uneven wear tends to occur. In particular, as shown in FIG. 4, the inventors have found that the inflection point of the composite code is preferably located at 2 to 4%.

  Moreover, when the number of the end blocks 21 is 0.5 times or more, particularly twice the number of the intermediate blocks 23, the diameter growth rate can be further suppressed, and uneven wear can be further suppressed. it can.

  Further, even when the inner end land portion width (W1-IN) is wider than the outer end portion land portion width (W1-OUT), even when the negative camber is set, the inner end portion land portion width (W1-IN) is positioned on the inner side when the vehicle is mounted. Since the wear of the end land portion 17A to be performed can be suppressed, the occurrence of uneven wear can be reduced.

[Other embodiments]
As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention.

  Specifically, the belt layer 11 and the belt reinforcing layer 13 have been described as being provided with one layer, but the present invention is not limited to this. For example, as shown in FIG. Of course it may be.

  Moreover, although the width direction groove | channel 19 demonstrated as what extended incline with respect to a tread width direction, it is not limited to this, You may extend substantially in parallel with the tread width direction.

  From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  Next, in order to further clarify the effects of the present invention, the results of tests performed using pneumatic tires according to the following Comparative Examples 1 to 3 and Examples 1 to 5 will be described. In addition, this invention is not limited at all by these examples.

  Data on each pneumatic tire was measured under the following conditions.

・ Tire size: 215 / 45R17
・ Wheel size: 7J × 17
・ Internal pressure condition: 200kPa
・ Load condition: 4.0kN
The configuration and wear test (tire life and wear life ratio) of each pneumatic tire will be described with reference to Table 1.

<Abrasion test (tire life)>
The passenger cars equipped with the respective pneumatic tires traveled on the same course, the tire life of the pneumatic tire according to Comparative Example 1 was set to “100”, and the tire lives of the other pneumatic tires were indexed. The larger the index, the longer the tire life.

  Here, the tire life refers to until the tread wear indicator or slip sign of the circumferential groove formed in the tread portion is visible or until the width direction groove (lug groove) formed in the end land portion disappears. .

  As a result, the pneumatic tire according to Examples 1 to 5 was found to have a longer tire life than the pneumatic tire according to Comparative Examples 1 to 3. In particular, a composite cord is used for the belt reinforcing layer, the end land width (W1) is 100 to 200% of the central land width (W2), and the number of end blocks is the number of intermediate blocks. It has been found that the tire life is increased by 0.5 times or more (particularly twice).

<Abrasion test (wear life ratio)>
Considering the ratio between the central land portion and the end land portion when each pneumatic tire is new, the wear amount between the central land portion and the end land portion during the tire life of each pneumatic tire was ratioed. Note that the closer the numerical value is to 100%, the more uniform the wear amount between the central land portion and the end land portion.

  As a result, the pneumatic tires according to Examples 1 to 5 are more uneven than the pneumatic tires according to Comparative Examples 1 to 3 because the wear amounts of the central land portion and the end land portion are nearly uniform. It turns out that it can suppress. In particular, a composite cord is used for the belt reinforcing layer, the end land width (W1) is 100 to 200% of the central land width (W2), and the number of end blocks is the number of intermediate blocks. It was found that the tire life is increased by 0.5 times or more (particularly twice) of the tire.

It is a tread width direction sectional view showing the pneumatic tire concerning this embodiment. It is a top view which shows the carcass layer, the belt layer, and the belt reinforcement layer which comprise the pneumatic tire which concerns on this Embodiment. It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a graph which compares the characteristic (strength and extension degree) of each cord. It is a tread width direction sectional view showing a pneumatic tire concerning other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 3 ... Bead part, 3a ... Bead core, 3b ... Bead filler, 5 ... Carcass layer, 7 ... Inner liner, 9 ... Tread part, 11 ... Belt layer, 11a ... End part of belt layer in the tread width direction , 13 ... belt reinforcing layer, 13A ... belt cord, 13B ... rubber, 15 ... circumferential groove, 17 ... land portion, 17A ... end land portion, 17B ... central land portion, 17C ... intermediate land portion, 19 ... width direction Groove, 21 ... end block, 23 ... intermediate block, CL ... tire equator line, TW ... tread ground contact width, C ... tread center, M ... tread intermediate, S ... tread end

Claims (6)

A belt layer provided on the outer side in the tire radial direction of the carcass layer forming the skeleton of the pneumatic tire;
Covering the tread width direction end of the belt layer toward the inner side in the tire radial direction, and a belt reinforcing layer disposed separately in the tread width direction; and
A tread portion provided on the outer side in the tire radial direction of the belt layer and the belt reinforcing layer and having a land portion formed by a plurality of circumferential grooves extending in the tire circumferential direction;
Of the land portions, the end land portion width (W1), which is the width in the tread width direction of the end land portion located at the tread end portion, is the tread width of the central land portion located in the tread center portion of the land portions. A pneumatic tire characterized by being 100 to 200% of a central land portion width (W2) which is a width with respect to a direction. The belt reinforcing layer is composed of a belt cord and rubber,
The pneumatic tire according to claim 1, wherein the belt cord is a composite cord in which a low elastic cord and a high elastic cord are twisted together. The low elastic cord is a nylon cord,
The pneumatic tire according to claim 2, wherein the highly elastic cord is an aramid cord. A plurality of widthwise grooves extending in the tread width direction are formed in the intermediate land portion and the end land portion formed between the end land portion and the central land portion,
The number of end blocks defined by the circumferential grooves and the width direction grooves in the end land portion is the number of intermediate blocks defined by the circumferential grooves and the width direction grooves in the intermediate land portion. The pneumatic tire according to claim 1, wherein the ratio is 0.5 times or more. A plurality of widthwise grooves extending in the tread width direction are formed in the intermediate land portion and the end land portion formed between the end land portion and the central land portion,
The number of end blocks defined by the circumferential grooves and the width direction grooves in the end land portion is the number of intermediate blocks defined by the circumferential grooves and the width direction grooves in the intermediate land portion. The pneumatic tire according to claim 1, wherein the pneumatic tire is twice as large.   The inner end land portion width (W1-IN), which is the width in the tread width direction of the end land portion located on the inner side when the vehicle is mounted with respect to the tire equator line, is the outer side when the vehicle is mounted with respect to the tire equator line. 2. The pneumatic tire according to claim 1, which is wider than an outer end land portion width (W 1 -OUT), which is a width of the end land portion positioned in the tread width direction.

Images