JP2011213202A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which further improves hydroplaning resistance while maintaining steering stability and wear resistance.SOLUTION: The pneumatic tire 1 has circumferential direction grooves 10 extending in the tire circumferential direction on a tread surface. The circumferential direction grooves 10 each has a bottom part 10B positioned inside the tire radial direction. A plurality of projections 20 extending in the tire circumferential direction and projecting toward the tread part are formed on the bottom part 10B.

Description

  The present invention relates to a pneumatic tire in which a circumferential groove extending along a tire circumferential direction is formed on a tread surface, and particularly relates to a pneumatic tire in which a decrease in drainage is suppressed.

  Conventionally, in a pneumatic tire mounted on a vehicle such as an automobile, it has always been sought to improve wet performance such as driving / braking performance on a wet road surface and steering stability. As one of the factors that affect wet performance, when driving at high speed on a road surface where rainwater has accumulated, water enters between the tire and the road surface, allowing the vehicle to slide on the water, and handle and brake Hydroplaning is a phenomenon that makes it difficult to operate.

  For example, with regard to improving hydroplaning resistance, pneumatic tires with a large number of circumferential grooves extending in the tire circumferential direction and wide width grooves extending in the tread width direction with respect to the tread contact surface where the tread tread is in contact with the road surface are widely used. Used (see, for example, Patent Document 1).

JP 2002-12007 (page 2-3, FIGS. 1 and 2)

  However, the conventional pneumatic tire described above has the following problems. In other words, in a pneumatic tire with increased circumferential grooves and width grooves, the hydroplaning resistance is improved, but the surface area of the block defined by the circumferential grooves and width grooves is reduced, and the tread contact surface land The part area is reduced. For this reason, there existed a problem that steering stability and abrasion resistance will fall.

    Accordingly, an object of the present invention is to provide a pneumatic tire that can further improve hydroplaning resistance while maintaining steering stability and wear resistance.

    In order to solve the above-described problems, the present invention has the following features. A first feature of the present invention is a pneumatic tire (pneumatic tire 1) in which a circumferential groove (circumferential groove 10) extending in the tire circumferential direction is formed on a tread surface, and the circumferential groove Has a bottom portion (bottom portion 10B) located on the inner side in the tire radial direction, and a plurality of projecting portions (projecting portions 20) extending in the tire circumferential direction and projecting toward the tread surface are formed on the bottom portion. The height in the tire radial direction (height H1) of the protrusion is 15% or less with respect to the depth (depth D) in the tire radial direction of the circumferential groove, and one protrusion The gist of the width in the tread width direction (width W1) is 15% or less with respect to the width in the tread width direction (width W6) in the circumferential groove.

    According to this feature, by forming a plurality of protrusions at the bottom of the circumferential groove, omnidirectional turbulence generated by the resistance of the wall surface of the circumferential groove can be rectified on the protrusion. . Therefore, rainwater can be smoothly discharged from the circumferential groove, and the hydroplaning resistance can be further improved.

    As a result, according to such a pneumatic tire, as the hydroplaning resistance is improved, it is not necessary to form a large number of circumferential grooves and width grooves as in the prior art. For this reason, the surface area of the block defined by the circumferential grooves and the width grooves increases, and the land area of the tread ground surface increases. Therefore, steering stability and wear resistance can be maintained.

    A second feature of the present invention is according to the first feature of the present invention, and is summarized in that the protruding portion has a tapered shape rounded toward the tread tread surface in a cross section in the tread width direction.

    A third feature of the present invention relates to the first or second feature of the present invention, wherein a distance between the protrusion and another protrusion formed in the same circumferential groove is at least in the tread width direction. The gist is that it is 1.2 times or more of the width in the tread width direction of the protruding portion.

    A fourth feature of the present invention relates to the first to third features of the present invention, wherein the center of the protruding portion in the tread width direction is obtained by dividing the width of the bottom portion in the tread width direction into four equal parts. The gist of the present invention is that it is provided so as to be located within an outer quarter of the tread width direction.

    A fifth feature of the present invention relates to the first to fourth features of the present invention, wherein the width of the protruding portion in the tread width direction is 10% to 60% with respect to the depth in the tire radial direction of the circumferential groove. It is a summary.

    A sixth feature of the present invention relates to the first to fifth features of the present invention, wherein the height of the protruding portion in the tire radial direction is 10 to 40% of the width in the tread width direction of the circumferential groove. It is a summary.

    A seventh feature of the present invention relates to the first to sixth features of the present invention, wherein the circumferential groove further has an upper end portion (upper end portion 10A) located on the tread tread side on the outer side in the tire radial direction. The gist of the bottom portion in the tread width direction (width W2) is 50 to 100% with respect to the tread width direction width in the upper end portion.

  According to the features of the present invention, it is possible to provide a pneumatic tire that can further improve hydroplaning resistance while maintaining steering stability and wear resistance.

FIG. 1 is a development view showing a tread pattern constituting a pneumatic tire 1 according to an embodiment of the present invention. FIG. 2 is a perspective view showing a part of the circumferential groove 10 according to the embodiment of the present invention. FIG. 3 is a cross-sectional view in the tread width direction showing a part of the circumferential groove 10 according to the embodiment of the present invention. FIG. 4 is a modified example of the protrusion 20 according to the embodiment of the present invention. FIG. 5 is a modified example of the tread pattern constituting the pneumatic tire 1 according to the embodiment of the present invention.

    Next, embodiments according to the present invention will be described with reference to the drawings. Specifically, (1) Configuration of pneumatic tire, (2) Configuration of circumferential groove, (3) Action and effect, (4) Comparative evaluation, (5) Other embodiments will be described.

  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 and the like are different from actual ones.

    Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Configuration of Pneumatic Tire First, the configuration of the pneumatic tire 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a development view showing a tread pattern constituting a pneumatic tire 1 according to an embodiment of the present invention.

  In addition, the pneumatic tire 1 concerning this embodiment is a general radial tire provided with a bead part, a carcass layer, and a belt layer (not shown).

  As shown in FIG. 1, in the pneumatic tire 1, a circumferential groove extending in the tire circumferential direction is formed on the tread surface. In the present embodiment, the pneumatic tire 1 has a circumferential groove 10 formed on the tire equator line CL, and a pair of circumferential grooves 10X and a circumferential groove 10Y formed on the outer side in the tread width direction. Yes. In the present embodiment, the center line in the tread width direction of the circumferential groove 10 is configured to coincide with the tire equator line CL.

(2) Configuration of circumferential groove Next, the configuration of the circumferential groove 10 according to the present embodiment will be described with reference to the drawings. FIG. 2 is a perspective view showing a part of the circumferential groove 10 according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view in the tread width direction showing a part of the circumferential groove 10 according to the embodiment of the present invention. In addition, although the structure of the circumferential groove | channel 10 is demonstrated below, it is the same structure as the circumferential groove | channel 10 also about the circumferential groove | channel 10X and the circumferential groove | channel 10Y.

  As described above, the circumferential groove 10 is a straight groove that extends in a straight line in the tire circumferential direction on the outer surface in the tire radial direction of the pneumatic tire 1.

  As shown in FIGS. 2 and 3, the circumferential groove 10 has an upper end portion 10 </ b> A located on the outer side in the tire radial direction and a bottom portion 10 </ b> B located on the inner side in the tire radial direction. The width W2 of the bottom portion 10B in the tread width direction is preferably 50% to 100% with respect to the width W6 of the upper end portion 10A in the tread width direction. A plurality of projecting portions 20 projecting outward in the tire radial direction are formed on the bottom portion 10B.

  The protrusion 20 extends in a straight line in the tire circumferential direction. In the present embodiment, two parallel projecting portions 20 (projecting portion 20A and projecting portion 20B) are formed on the bottom portion 10B on the outer side in the tread width direction on the basis of the tire equator line CL.

  In the tread width direction sectional view, the protruding portion 20 has a tip portion 20R having a tapered shape rounded toward the tread surface. The protruding portion 20 is connected to the bottom portion 10B in a round shape (R shape).

  The height H1 of the protrusion 20 in the tire radial direction is 15% or less with respect to the depth D of the circumferential groove 10 in the tire radial direction. In addition, it is preferable that the height H1 of the protrusion part 20 in the tire radial direction is 10 to 40% with respect to the width W6 of the circumferential groove 10 in the tread width direction. In particular, the height H1 of the protrusion 20 in the tire radial direction is preferably 1 to 5 mm.

  The width W1 in the tread width direction of the protrusion 20 is 15% or less with respect to the width W6 in the tread width direction of the circumferential groove 10 in the upper end portion 10A. In addition, it is preferable that the width W1 of the protrusion part 20 in the tread width direction is 10 to 60% with respect to the depth D of the circumferential groove 10 in the tire radial direction. In particular, the width W1 of the protruding portion 20 in the tread width direction is preferably 1 to 5 mm.

  As shown in FIG. 3, the distance S between the two protruding portions 20 in the tread width direction, specifically, the inner end portion of the protruding portion 20A in the tread width direction and the inner end portion of the protruding portion 20B in the tread width direction. The distance is at least 1.2 times the width W1 of the protrusion 20 in the tread width direction.

  Further, the center (center 20AC, center 20BC) of each protrusion 20 in the tread width direction is the outer quarter of the bottom 10B in the tread width direction when the width W2 of the bottom 10B is divided into four equal parts. It is configured to be positioned within the range (range RA, range RB). In FIG. 3, the center 20AC of the projecting portion 20A is configured to be in the range RA, and the center 20BC of the projecting portion 20B is configured to be in the range RB.

  In FIG. 3, the outer widths when the width W2 of the bottom portion 10B in the tread width direction is equally divided into four are the width W4 and the width W4 ′.

(3) Action / Effect In this embodiment, by forming a plurality of protrusions 20 on the bottom 10B of the circumferential groove 10, omnidirectional turbulence generated by the resistance of the wall surface of the circumferential groove 10 is obtained. Rectification can be performed on the protrusion 20 along the tire circumferential direction. As a result, rainwater can be drained smoothly from the circumferential groove 10, and the hydroplaning resistance can be further improved.

    As a result, according to such a pneumatic tire 1, as the hydroplaning resistance is improved, it is not necessary to form a large number of circumferential grooves and width grooves as in the prior art. For this reason, the surface area of the block defined by the circumferential grooves and the width grooves increases, and the land area of the tread ground surface increases. Therefore, steering stability and wear resistance can be maintained.

    In the present embodiment, the height H1 of the protruding portion 20 in the tire radial direction is 15% or less with respect to the depth D of the circumferential groove 10 in the tire radial direction. When the height H1 is greater than 15% with respect to the depth D, the volume in the circumferential groove 10 decreases, rainwater hardly flows, and wet performance may be degraded.

    In the present embodiment, the width W1 in the tread width direction of the protrusion 20 is 15% or less with respect to the width W6 in the tread width direction of the circumferential groove 10 in the upper end portion 10A. Note that if the width W1 is larger than 15% with respect to the width W6, the volume in the circumferential groove 10 decreases, rainwater hardly flows, and wet performance may deteriorate.

    In the present embodiment, the tip 20R of the protrusion 20 has a rounded taper shape, and the tip 20R is less likely to be damaged than the case where the tip 20R has a corner portion, and the durability of the protrusion 20 is improved. .

    In the present embodiment, the distance S, which is the distance between the inner end of the protrusion 20A in the tread width direction and the inner end of the protrusion 20B in the tread width direction, is the width W1 of the protrusion 20 in the tread width direction. 1.2 times or more. When the interval S is smaller than 1.2 times the width W1 and formed on the inner side in the tread width direction, the turbulent flow generated by the rainwater entering the circumferential groove 10 hitting the lateral wall of the circumferential groove 10 is arranged. May become difficult and the hydroplaning resistance may decrease.

    In the present embodiment, the center 20AC of the protruding portion 20A is configured to be positioned within the range RA, and the center 20BC of the protruding portion 20B is positioned within the range RB. When the center 20AC and the center 20BC are formed not in the range RA and the range RB but on the inner side in the tread width direction, rainwater that has entered the circumferential groove 10 hits the lateral wall of the circumferential groove 10. It becomes difficult to arrange the turbulent flow generated by the water and the hydroplaning resistance may be lowered.

  In the present embodiment, the width W1 of the protruding portion 20 in the tread width direction is 10 to 60% with respect to the depth D of the circumferential groove 10 in the tire radial direction. If the width W1 is smaller than 10% with respect to the depth D, turbulence of rainwater tends to occur at the bottom 10B of the circumferential groove 10 and the hydroplaning resistance may be reduced. On the other hand, when the width W1 is larger than 60% with respect to the depth D, the volume in the circumferential groove 10 decreases, rainwater hardly flows, and the wet performance may deteriorate.

  In the present embodiment, the height H1 of the protruding portion 20 in the tire radial direction is 10 to 40% with respect to the width W6 of the circumferential groove 10 in the tread width direction. If the height H1 is smaller than 10% with respect to the width W6, turbulence of rainwater tends to occur at the bottom 10B of the circumferential groove 10, and the hydroplaning resistance may be reduced. On the other hand, if the height H1 is larger than 40% with respect to the width W6, the volume in the circumferential groove 10 decreases, rainwater hardly flows, and the wet performance may deteriorate.

  In the present embodiment, the circumferential groove 10 has an upper end portion 10A located on the outer side in the tire radial direction and a bottom portion 10B located on the inner side in the tire radial direction. The width W2 of the bottom portion 10B in the tread width direction is the upper end portion. It is 50% to 100% with respect to the width W6 in the tread width direction in the portion 10A. If the width W2 is smaller than 50% with respect to the width W6, the volume in the circumferential groove 10 decreases, rainwater hardly flows, and the wet performance may be reduced. Furthermore, since the width W2 becomes small, it becomes difficult to configure the necessary protrusion 20. On the other hand, if the width W2 is larger than 100% with respect to the width W6, turbulence of rainwater is likely to occur at the bottom 10B of the circumferential groove 10, and the hydroplaning resistance may be reduced.

(4) Comparative Evaluation Next, in order to further clarify the effects of the present invention, test evaluations performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4.1) Evaluation method and (4.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Evaluation method Hydroplaning performance was evaluated using three types of pneumatic tires.

Data on pneumatic tires were measured under the following conditions.

・ Tire size: 225 / 45R17
・ Rim wheel size: 17 × 7J
-Tire type: Normal tire (tires other than studless tires)
-Vehicle type: Domestic car sedan-Load condition: 600N + driver's weight-Measuring method: Measure the speed at which hydroplaning occurred at a water depth of 10mm. The obtained speed was set to 100 and displayed as an index. Moreover, all the pneumatic tires used in this evaluation have a circumferential groove depth of 7 mm in the tire radial direction and a width in the tread width direction of 10 mm.

  Each configuration of the pneumatic tire used in the comparative example is shown in the table.

(4.2) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 1.

  As a result, it can be seen that the pneumatic tire 1 according to Example 1 has superior hydroplaning performance as compared with the pneumatic tires according to Comparative Examples 1 and 2.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows.

(Modification 1)
As shown in FIGS. 4A and 4B, the protrusion 20 may have a shape in which the width in the tread width direction decreases linearly toward the tread surface in the tread width direction sectional view. Specifically, in the cross-sectional view in the tread width direction, a trapezoidal shape (FIG. 4A) whose lower side is longer than the upper side or a triangular shape (FIG. 4B) may be used.

(Modification 2)
As shown in FIG. 5, at least one circumferential groove 10 on which the protruding portion 20 is formed is sufficient. Moreover, the width direction groove | channel 30 extended in a tread width direction may be formed.

  The configurations (number, shape, etc.) of the circumferential grooves and the protruding portions are not limited to those described in the embodiment, and can be appropriately selected according to the purpose.

  As described above, the present invention naturally includes various embodiments that are not described herein. 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.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 10, 10X, 10Y ... Circumferential groove | channel 10A ... Upper end part, 10B ... Bottom part, 20, 20A, 20B ... Projection part, 20AC, 20BC ... Center, 20R ... Tip part, 30 ... Width direction groove | channel , CL ... tire equator line, D ... depth, H1 ... height, RA, RB ... range, S ... interval, W1, W2, W4, W4 ', W6 ... width

Claims (7)

On the tread surface, a pneumatic tire in which a circumferential groove extending in the tire circumferential direction is formed,
The circumferential groove has a bottom portion located on the inner side in the tire radial direction,
The bottom portion is formed with a plurality of protrusions extending in the tire circumferential direction and protruding toward the tread surface,
The height of the protruding portion in the tire radial direction is 15% or less with respect to the depth in the tire radial direction of the circumferential groove,
The pneumatic tire according to claim 1, wherein a width of one protruding portion in the tread width direction is 15% or less with respect to a width in the tread width direction of the circumferential groove.   2. The pneumatic tire according to claim 1, wherein at least a part of the protruding portion has a tapered shape in which a width becomes narrower toward a tread surface in a tread width direction cross section.   The interval in the tread width direction between the protrusion and another protrusion formed in the same circumferential groove is at least 1.2 times the width of the protrusion in the tread width direction. The pneumatic tire according to claim 1 or 2.   The center of the protruding portion in the tread width direction is provided so as to be located within the outer quarter of the tread width direction of the bottom portion when the width of the bottom portion in the tread width direction is equally divided into four. The pneumatic tire according to any one of claims 1 to 3, wherein:   5. The air according to claim 1, wherein a width of the protruding portion in a tread width direction is 10 to 60% with respect to a tire radial direction depth of the circumferential groove. Enter tire.   The air according to any one of claims 1 to 5, wherein a height of the protruding portion in the tire radial direction is 10 to 40% with respect to a width of the circumferential groove in a tread width direction. Enter tire. The circumferential groove further has an upper end located on the tread tread side on the outer side in the tire radial direction,
The pneumatic tire according to any one of claims 1 to 6, wherein a width in the tread width direction at the bottom portion is 50 to 100% with respect to a width in the tread width direction at the upper end portion.

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