JP5238300B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which an inclined lug groove extending obliquely with respect to the tread width direction is formed.

2. Description of the Related Art Conventionally, in a pneumatic tire mounted on a vehicle such as an automobile, an inclined lug groove extending obliquely with respect to the tread width direction, for example, passes through the center of the tread width direction and is orthogonal to the rotation axis of the pneumatic tire A tread pattern in which an inclined lug groove is formed near the tire equator line is known (for example, Patent Document 1).
JP-A-8-276707 (FIG. 3)

  However, the conventional pneumatic tire described above has the following problems. That is, when the inclined lug groove extending obliquely with respect to the tread width direction is formed, there is a problem that the outer shape of the inclined lug groove portion is likely to change when the pneumatic tire is set to a prescribed internal pressure.

  Specifically, the inclined lug groove and the vicinity of the inclined lug groove have no tread rubber thickness compared to the other parts, so that the air filled in the pneumatic tire deforms more than the other parts. It becomes easy. In particular, when the width of the inclined lug groove formed in the vicinity of the tire equator line is wide, the belt reinforcing layer disposed on the outer side in the tire radial direction of the belt layer for fastening the carcass layer is formed in the region where the inclined lug groove is formed ( Specifically, since there is no outer reinforcing layer (layer layer) that covers both end portions of the inner layer, the inclined lug groove portion is further easily deformed.

  That is, since the inclined lug groove portion swells outward in the tire radial direction from the other portions, the roundness of the pneumatic tire is reduced and the crown shape is not uniform. For this reason, the improvement of the braking / driving function and steering stability (course holding performance) of the pneumatic tire is hindered.

  Therefore, the present invention has been made in view of such problems, and in the case where an inclined lug groove extending obliquely with respect to the tread width direction is formed in the vicinity of the tire equator line, the braking / driving function and the steering operation are performed. An object of the present invention is to provide a pneumatic tire capable of further improving the stability.

  In order to solve the above situation, the present invention has the following features. First, the invention according to the first feature of the present invention is a pneumatic tire in which an inclined lug groove extending obliquely with respect to the tread width direction is formed, and a tire diameter of a carcass layer forming a skeleton of the pneumatic tire. A belt layer disposed on the outer side in the tire direction, and a belt reinforcing layer disposed on the outer side in the tire radial direction of the belt layer, the belt reinforcing layer covering the belt layer toward the inner side in the tire radial direction; The outer reinforcing layer disposed on the outer side in the tire radial direction of the inner reinforcing layer and covering one end portion in the tread width direction of the inner reinforcing layer or the other end portion in the tread width direction of the inner reinforcing layer, The inner end which is the end located on the tire equator line side of the outer reinforcing layer is in the tire radial direction and the lug equator side region including the equator side end which is the end located on the tire equator line side of the inclined lug groove. The gist is that they overlap.

  According to this feature, the inner end of the outer reinforcing layer overlaps with the lug equator side region in the tire radial direction, so that there is no tread rubber thickness compared to other portions where the inclined lug grooves are not formed. Since the rigidity of the lug groove and the vicinity of the inclined lug groove can be ensured, and the decrease in roundness of the pneumatic tire and the unevenness of the crown shape can be suppressed, the braking / driving function of the pneumatic tire And steering stability (track keeping performance) can be improved.

  Another feature is summarized in that the lug equator side region is a region of 2 to 25% with respect to the tread contact width from the tire equator line to the tread shoulder.

  Another feature is that the outer reinforcing layer width, which is the width along the tread width direction of the outer reinforcing layer, determines the distance from the outer end, which is the end located on the tread shoulder side of the outer reinforcing layer, to the equator side end. When it is set to 100, the gist is that it is 75 to 125% with the outer end as a base point.

  According to this feature, the outer reinforcing layer width is 75 to 125% with the outer end as the base point, thereby reliably improving the rigidity of the inclined lug groove without the thickness of the tread rubber and the vicinity of the inclined lug groove. It is possible to reliably reduce the roundness of the pneumatic tire and the unevenness of the crown shape.

  Another feature is summarized in that the inclined lug groove extends obliquely with respect to the tread width direction from the tire equator portion including the tire equator line.

  According to this feature, even when the inclined lug groove is formed in the tire equator portion by extending the inclined lug groove obliquely with respect to the tread width direction from the tire equator portion, the roundness of the pneumatic tire is increased. And the unevenness of the crown shape can be suppressed, and the braking / driving function and steering stability (track holding performance) of the pneumatic tire can be improved.

  Another feature is that the equator side end width, which is the width along the tire circumferential direction of the equator side end, is the width along the tire circumferential direction of the shoulder side end, which is the end located on the tread shoulder side. The gist is that it is wider than a certain shoulder side end width.

  According to such a feature, since the equator side end width is wider than the shoulder side end width, in particular, even when the equator side end width is wide, the roundness of the pneumatic tire is reduced, the crown Nonuniformity of the shape can be suppressed.

  Another feature is that the inclined lug groove is formed with a lug-inclined bottom that gradually increases in depth from the equator-side end to the shoulder-side end located on the tread shoulder side. To do.

  According to such a feature, the lug inclined bottom portion is formed in the inclined lug groove, so that even if the shape of the inclined lug groove is complicated and easily deformed, the roundness of the pneumatic tire is reduced and the crown is reduced. Nonuniformity of the shape can be suppressed.

  Another feature is that the inclined lug groove is formed with a flat lug bottom that is constant in depth from the equator side end to the shoulder side end located on the tread shoulder side. The gist is that it is formed on the outer side in the tread width direction than the inclined bottom portion.

  Another feature is that the lug slope bottom portion gradually increases in width along the tire circumferential direction.

  According to the present invention, there is provided a pneumatic tire capable of further improving braking / driving function and driving stability when an inclined lug groove extending obliquely with respect to the tread width direction is formed near the tire equator line. 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.

  FIG. 1 is a perspective view showing a pneumatic tire according to the present embodiment, and FIG. 2 is a cross-sectional view in the tread width direction showing the pneumatic tire according to the present embodiment.

  As shown in FIGS. 1 and 2, a pneumatic tire 1 includes a pair of bead portions 10 including at least a bead core 10 a and a bead filler 10 b, and a carcass that is folded back by the bead core 10 a and forms a skeleton of the pneumatic tire 1. Layer 20.

  An inner liner 30 that is a highly airtight rubber layer corresponding to a tube is disposed inside the carcass layer 20. A tread portion 40 where a tread pattern is formed is formed on the outer side of the carcass layer 20 in the tire radial direction.

  Between the carcass layer 20 and the tread portion 40, a belt layer 50 that fastens the carcass layer 20 and a belt reinforcing layer 60 that reinforces the belt layer 50 are disposed.

  The belt layer 50 includes an inner belt layer 51 positioned on the outer side in the tire radial direction of the carcass layer 20 and an outer belt layer 52 positioned on the outer side in the tire radial direction of the inner belt layer 51.

  The belt reinforcing layer 60 includes an inner reinforcing layer 61 that covers the belt layer 50 (the inner belt layer 51 and the outer belt layer 52) toward the inner side in the tire radial direction, and an outer reinforcing member that is positioned on the outer side in the tire radial direction of the inner reinforcing layer 61. Layer 62.

  The inner reinforcing layer 61 has a width extending from one tread shoulder S of the pneumatic tire 1 to the other tread shoulder S.

  The outer reinforcing layer 62 covers one end 61A of the inner reinforcing layer 61 in the tread width direction or the other end 61B of the inner reinforcing layer 61 in the tread width direction. Specifically, the outer reinforcing layer 62 has an inner end 62A that is an end located on the tire equator line CL side and an outer end 62B that is an end located on the tread shoulder S side. . That is, the outer reinforcing layer 62 is divided in the vicinity of the tire equator line CL by separating one inner end 62A and the other inner end 62A.

(Configuration of tread pattern and outer reinforcing layer)
Next, a specific configuration of the tread pattern formed on the tread portion 40 and the outer reinforcing layer 62 will be described with reference to FIGS. FIG. 3 is a development view showing a tread pattern of the pneumatic tire according to the present embodiment.

  As shown in FIGS. 1 to 3, the tread portion 40 has an inclined rib groove 41 that extends obliquely with respect to the tire circumferential direction, and an inclination that continues to the inclined rib groove 41 and extends obliquely with respect to the tread width direction. A lug groove 42 is formed.

  In the inclined rib groove 41, a rib inclined bottom portion 41A that gradually increases from the surface of the tread portion 40 toward the outer side in the tread width direction and a rib flat bottom portion 41B that has a constant depth in the tire circumferential direction are formed. .

  The inclined lug groove 42 extends obliquely with respect to the tread width direction from the tire equator portion C including the tire equator line CL. The tire equator portion C indicates a tread width direction central portion including the tire equator line CL, and for example, indicates a range of 0 to 15% with respect to the tread ground contact width TW with the tire equator line CL as a base point.

  The inclined lug groove 42 has an equator end 42A that is an end located on the tire equator line CL side, and a shoulder side end 42B that is an end located on the tread shoulder S side.

  The equator-side end width (DW1) that is the width along the tire circumferential direction of the equator-side end portion 42A is larger than the shoulder-side end width (DW2) that is the width along the tire circumferential direction of the shoulder-side end portion 42B. Is also wide.

  The inclined lug groove 42 has a lug inclined bottom portion 43A that gradually increases in depth from the equator side end portion 42A to the shoulder side end portion 42B, and a constant depth from the equator side end portion 42A to the shoulder side end portion 42B. A flat lug bottom 43B is formed.

  The lug inclined bottom portion 43A gradually increases in width (W) along the tire circumferential direction. In addition, the lug flat bottom portion 43B is formed on the outer side in the tread width direction than the inclined groove bottom portion 43A.

  Here, the inner end portion 62A of the outer reinforcing layer 62 overlaps the lug equator side region RS including the equator side end portion 42A that is an end portion of the inclined lug groove 42 located on the tire equator line CL side in the tire radial direction. That is, the outer reinforcing layer 62 is disposed from the equator side end portion 42A of the inclined lug groove 42 toward the outer side in the tread width direction, and is divided in the vicinity of the tire equator line CL. Note that the lag equator-side region RS indicates a region of 2 to 25% with respect to the tread ground contact width TW.

  The outer reinforcing layer width (SW), which is the width along the tread width direction of the outer reinforcing layer 62, is the distance from the outer end 62B of the outer reinforcing layer 62 to the equator side end 42A of the inclined lug groove 42. In this case, it is 75 to 125% based on the outer end 62B.

  As shown in FIGS. 4 (a) and 4 (b), when the outer reinforcing layer width (SW) is smaller than 75% with the outer end 62B as the base point, the tread rubber is made of the tread rubber as compared with other portions. It is difficult to ensure the rigidity of the inclined lug groove 42 having no thickness and the vicinity of the inclined lug groove 42 by the outer reinforcing layer 62, and it is possible to reliably reduce the roundness of the pneumatic tire 1 and the unevenness of the crown shape. In some cases, it cannot be suppressed, and as a result, the braking / driving function and steering stability (track keeping performance) of the pneumatic tire 1 cannot be improved (that is, the lap time does not increase). On the other hand, if the outer reinforcing layer width (SW) is larger than 125% based on the outer end 62B, one outer reinforcing layer 62 and the other outer reinforcing layer 62 may overlap each other. In some cases, the braking / driving function and steering stability (track keeping performance) of the pneumatic tire cannot be improved (that is, the lap time does not increase).

(Action / Effect)
According to the pneumatic tire according to the present embodiment described above, the inclined end lug groove 42 is formed by the inner end 62A of the outer reinforcing layer 62 overlapping the inclined lug groove 42 in the tire radial direction with the lug equator side region RS. Compared with other parts that are not made, the rigidity of the inclined lug groove 42 without the thickness of the tread rubber and the vicinity of the inclined lug groove 42 can be secured, and when the pneumatic tire 1 is set to a prescribed internal pressure In addition, the outer shape of the inclined lug groove 42 is difficult to change.

  As a result, by obtaining an appropriate and uniform ground contact shape, it is possible to suppress a decrease in roundness of the pneumatic tire 1 and a non-uniform crown shape. Steering stability (track keeping performance) can be improved.

  Further, when the inclined lug groove 42 is formed in the tire equator portion C, or particularly when the width of the equator side end portion (DW1) is wide, even if the inclined lug groove shape is complicated and easily deformed, it is inflated. It is possible to suppress a decrease in the roundness of the tire 1 and unevenness of the crown shape, and to improve the braking / driving function and steering stability (track holding performance) of the pneumatic tire 1.

[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 outer reinforcing layer 62 has been described as being disposed on both tread shoulder S sides, but is not limited to this, and is disposed only on one (one side). May be.

  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 examples and comparative examples 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: 255 / 40R17
・ Wheel size: 17 × 9J
・ Internal pressure condition: 230kPa
・ Vehicle condition: FR car (displacement 2000cc)
In the pneumatic tire according to the example, as shown in FIG. 5A, the outer reinforcing layer 62 is disposed on the outer side in the tread width direction from the equator side end portion 42 </ b> A of the inclined lug groove 42. That is, in the pneumatic tire according to the example, the inner end portion 62A of the outer reinforcing layer 62 overlaps the equator side end portion 42A (lag equator region RS) of the inclined lug groove 42.

  In the pneumatic tire according to the comparative example, as shown in FIG. 5B, the outer reinforcing layer 62 is disposed on the outer side in the tread width direction from the middle portion of the inclined lug groove 42. That is, in the pneumatic tire according to the comparative example, the inner end 62A of the outer reinforcing layer 62 does not overlap with the equator-side end 42A (lag equator region RS) of the inclined lug groove 42. The configuration other than the outer reinforcing layer of the pneumatic tire according to the comparative example is the same as the configuration of the pneumatic tire according to the example.

The running performance of the pneumatic tire according to this example and the comparative example will be described with reference to Table 1.

<Running performance>
Driving on a race course with a vehicle equipped with each pneumatic tire, the driving stability of the pneumatic tire according to the comparative example and the driving performance such as lap time are set to “100”, and the driving stability of the pneumatic tire according to the embodiment is stabilized. The feeling was evaluated by a professional driver. The larger the index, the better the steering stability.

  As a result, in the pneumatic tire according to the comparative example, the inner end portion 62A of the outer reinforcing layer 62 does not overlap the equator side end portion 42A (lag equator region RS) of the inclined lug groove 42. The rigidity in the vicinity of the equator side end portion 42A is insufficient, and when the tread portion 40 contacts the ground, an increase in the contact length, which is the length in the tire circumferential direction, is caused (see FIG. 5B). Thereby, in the vehicle equipped with the pneumatic tire according to the comparative example, it was evaluated that the feeling of stalling was strong and the acceleration during climbing was heavy.

  On the other hand, in the pneumatic tire according to the example, the inner end 62A of the outer reinforcing layer 62 overlaps the equator side end 42A (lag equator region RS) of the inclined lug groove 42. The rigidity in the vicinity of the side end portion 42A is improved, the contact length is reduced, and a uniform contact shape can be obtained (see FIG. 5A). Thereby, in the vehicle equipped with the pneumatic tire according to the example, the steering is good and the vehicle is easy to turn.

  As described above, in the pneumatic tire according to the example, the inner end 62A of the outer reinforcing layer 62 overlaps with the equator side end 42A (lag equator region RS) of the inclined lug groove 42, that is, the inclined lug groove. Since the outer reinforcing layer 62 is disposed at the equator-side end portion 42A of 42, compared to the pneumatic tire according to the comparative example, the braking / driving function and the steering stability (the course holding performance) are excellent. The lap time could be shortened (see FIG. 4).

It is a perspective view which shows the pneumatic tire which concerns on this Embodiment. It is a tread width direction sectional view showing the pneumatic tire concerning this embodiment. It is an expanded view which shows the tread pattern of the pneumatic tire which concerns on this Embodiment. It is a table | surface / graph which shows the lap time by the arrangement | positioning location of the outer side reinforcement layer of the pneumatic tire which concerns on an Example. It is a figure which shows the contact shape of the pneumatic tire which concerns on an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 10 ... Bead part, 10a ... Bead core, 10b ... Bead filler, 20 ... Carcass layer, 30 ... Inner liner, 40 ... Tread part, 41 ... Inclined rib groove, 41A ... Rib inclined bottom part, 41B ... Rib Flat bottom, 42 ... inclined lug groove, 42A ... equatorial side end, 42B ... shoulder side end, 43A ... lug inclined bottom, 43A ... inclined groove bottom, 43B ... lug flat bottom, 50 ... belt layer, 51 ... inner belt Layer, 52 ... outer belt layer, 60 ... belt reinforcing layer, 61 ... inner reinforcing layer, 61A ... one end, 61B ... the other end, 62 ... outer reinforcing layer, 62A ... inner end, 62B ... outer end Part, CL ... tire equator line, C ... tire equator part, RS ... lag equator side area, S ... tread shoulder

Claims (5)

A pneumatic tire in which an inclined lug groove extending obliquely with respect to the tread width direction is formed,
A belt layer disposed on the outer side in the tire radial direction of the carcass layer forming the skeleton of the pneumatic tire;
A belt reinforcing layer disposed on the outer side in the tire radial direction of the belt layer,
The belt reinforcing layer is
An inner reinforcing layer that covers the belt layer inward in the tire radial direction;
An outer reinforcing layer disposed on the outer side in the tire radial direction of the inner reinforcing layer and covering one end of the inner reinforcing layer in the tread width direction or the other end of the inner reinforcing layer in the tread width direction; Have
An inner end that is an end located on the tire equator line side of the outer reinforcing layer is a region including an equator side end that is an end located on the tire equator line side of the inclined lug groove , and the tire equator heavy Do Ri the lug equator side region and the tire radial direction is 2 to 25% of the area of the tread contact width from the line to the tread shoulder,
The equator side end width which is the width along the tire circumferential direction of the equator side end is the width along the tire circumferential direction of the shoulder side end which is the end located on the tread shoulder side of the inclined lug groove. Is wider than the shoulder side end width,
A pneumatic tire in which the inclined lug groove is formed with an inclined lug bottom that gradually increases in depth from the equator side end to the shoulder side end .   The outer reinforcing layer width, which is the width along the tread width direction of the outer reinforcing layer, is the distance from the outer end portion, which is the end portion located on the tread shoulder side of the outer reinforcing layer, to the equator side end portion as 100. 2. The pneumatic tire according to claim 1, wherein the pneumatic tire is 75 to 125% based on the outer end portion.   The pneumatic tire according to claim 1, wherein the inclined lug groove extends obliquely with respect to the tread width direction from a tire equator including the tire equator line. In the inclined lug groove, a rug flat bottom portion having a constant depth is formed from the equator side end portion to a shoulder side end portion which is an end portion located on the tread shoulder side,
The pneumatic tire according to claim 1 , wherein the lug flat bottom portion is formed on the outer side in the tread width direction than the lug inclined bottom portion. The pneumatic tire according to claim 1 , wherein the lug inclined bottom portion gradually increases in width along the tire circumferential direction.

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