JP2012188047A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of crack in a groove bottom of a circumferential main groove in a tire in which the tread width-direction groove width of the circumferential main groove changes at a predetermined cycle period, and also to improve the drainage performance of such a tire.SOLUTION: In a pneumatic tire 1, a groove wall 10a and a groove wall 20a extend in tire circumferential direction while meandering in a tread face view, and a groove width of a main groove 50 changes at a predetermined cycle along the tread width direction. The groove wall 10a and the groove wall 20a are symmetrical with respect to a straight line passing a tread width-direction center of a groove width of the main groove 50 and extending along the tire circumferential direction as a symmetry axis, in the tread face view. Projections 70 projected to outside in tire radial direction and extending in a tire circumferential direction, are formed in the bottom 50btm of the main groove 50.

Description

  The present invention relates to a tire in which a main groove extending in the tire circumferential direction is formed, and more particularly to a tire in which a decrease in drainage is suppressed.

  Conventionally, a tire is known in which the groove width in the tread width direction of the circumferential main groove extending in the tire circumferential direction changes at a predetermined cycle (see, for example, Patent Document 1). Specifically, the wide and narrow portions of the circumferential main grooves are continuously repeated. According to such a tire, the water present in the circumferential main groove flows along the groove wall of the circumferential groove while pulsating at the time of rolling of the tire, so that the drainage performance and consequently the hydroplaning performance can be improved. .

JP 2010-179892

  However, in the conventional pneumatic tire described above, the water flowing in the circumferential main groove moves along one groove wall when moving from a wide portion to a narrow portion of the groove wall of the tire circumferential main groove. The flowing water and the water flowing along the other groove wall collide with each other at a portion where the interval between the groove walls is narrow, and turbulent flow may occur. As a result, the flow of water may stagnate, and further improvement has been demanded.

  Further, since the interval between the circumferential main grooves is partially increased, it is conceivable that pebbles hit the groove bottom and cracks occur in the groove bottom. It is possible to provide a raised part that rises from the groove bottom in the part where the groove width of the circumferential main groove is partially widened, but there is a possibility that pebbles may hit the groove bottom of the narrow part of the circumferential main groove Was left.

  Therefore, the present invention provides a tire in which drainage performance is improved while suppressing occurrence of cracks in the groove bottom in a tire in which the groove width in the tread width direction of the circumferential main groove changes at a predetermined repetition period. For the purpose of provision.

  In order to solve the above-described problems, the present invention has the following features. A feature of the present invention is that a first land portion (land portion 10) that extends in the tire circumferential direction and contacts the road surface, and a second land portion (land portion 20) that extends in the tire circumferential direction and contacts the road surface. A main groove (main groove 50) extending in the tire circumferential direction is formed between the first land portion and the second land portion, and the first land portion is a first groove forming the main groove. The second land portion has a second groove wall (groove wall 20a) forming the main groove, and the first groove wall and the second groove wall are treads. In the plan view, the tire extends in the tire circumferential direction while meandering, and the groove width of the main groove along the tread width direction changes at a predetermined cycle along the tread width direction. And the straight line along the tire circumferential direction passing through the center in the tread width direction of the groove width of the main groove, The first groove wall and the second groove wall are symmetrical, and a protrusion (protrusion 70) that protrudes outward in the tire radial direction and extends in the tire circumferential direction is formed on the groove bottom (bottom 50btm) of the main groove. It is a summary.

  Further, the protrusions may be arranged symmetrically in the tread width direction with the straight line as the axis of symmetry.

  The protrusion may have a protrusion arranged on the straight line.

  Moreover, the width in the tread width direction of the protrusion may be reduced as it goes outward in the tire radial direction.

  According to the features of the present invention, in the tire in which the groove width in the tread width direction of the circumferential main groove changes at a predetermined repetition period, the drainage performance is improved while suppressing the occurrence of cracks at the groove bottom. Can do.

FIG. 1 is a development view of a tread constituting a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the pneumatic tire according to the embodiment of the present invention along the tread width direction and the tire radial direction. FIG. 3 is a partially enlarged view of a development view of a tread constituting the pneumatic tire according to the embodiment of the present invention. Fig.4 (a) is sectional drawing along the tread width direction and tire radial direction of the pneumatic tire which concerns on other embodiment of this invention. FIG.4 (b) is sectional drawing along the tread width direction and tire radial direction of the pneumatic tire which concerns on other embodiment of this invention.

  Next, embodiments and other embodiments 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 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.

[Embodiment]
In the present embodiment, (1.1) the configuration of the pneumatic tire, (1.2) the detailed configuration of the main groove, and (1.3) the operation / effect will be described.

(1.1) Configuration of Pneumatic Tire FIG. 1 is a development view of a tread that constitutes the pneumatic tire 1 in the present embodiment. Each part formed in the tread surface in the pneumatic tire 1 will be described. Specifically, (1.1.1) land portion and (1.1.2) main groove will be described.

(1.1.1) Land portion The pneumatic tire 1 includes a land portion 10, a land portion 20, and a land portion 30 that extend in the tire circumferential direction and come into contact with the road surface.

  The land portion 10 has a groove wall 10a that forms a main groove 50 at the inner end portion in the tread width direction. The land portion 10 has a groove wall 10b that forms a main groove 60 at an outer end portion in the tread width direction. The land portion 20 has a groove wall 20a that forms a main groove 50 at the inner end portion in the tread width direction. The land portion 20 has a groove wall 20b that forms a main groove 60 at an outer end portion in the tread width direction. The land portion 30 has a groove wall 30a that forms a main groove 60 at the inner end portion in the tread width direction. The land portion 30 has a lateral groove 110 that opens outward in the tread width direction.

  In the land portion 10 and the land portion 20, a lateral groove that intersects with the main groove 50 is not formed. In the land portion 10, the land portion 20, and the land portion 30, a lateral groove that intersects with the main groove 60 is not formed.

(1.1.2) Main groove The pneumatic tire 1 includes a main groove 50 extending between the land portion 10 and the land portion 20 in the tire circumferential direction. The pneumatic tire 1 includes a main groove 60 that extends between the land portion 10 and the land portion 30 in the tire circumferential direction. The pneumatic tire 1 includes a main groove 60 that extends between the land portion 20 and the land portion 30 in the tire circumferential direction.

  The main groove 50 is provided on the tire equator line CL. The main groove 60 is provided on the outer side in the tread width direction from the tire equator line CL.

  The main groove 60 extends linearly along the tire circumferential direction. That is, the groove wall 10b of the land portion 10, the groove wall 20b of the land portion 20, and the groove wall 30a of the land portion 30 extend linearly along the tire circumferential direction.

(1.2) Detailed Configuration of Main Groove 50 The detailed configuration of the main groove 50 will be described. Specifically, (1.2.1) groove wall, (1.2.2) groove width, and (1.2.3) the detailed configuration of the amplitude and period of the main groove will be described with reference to FIGS. I will explain. 2 is a cross-sectional view taken along line AA in FIG. Specifically, FIG. 2 is a cross-sectional view of the pneumatic tire 1 along the tread width direction and the tire radial direction. FIG. 3 shows an expanded view of the main groove 50 in the tread constituting the pneumatic tire 1.

(1.2.1) Groove Wall The main groove 50 is formed by the groove wall 10 a of the land portion 10 and the groove wall 20 a of the land portion 20. The groove wall 10a and the groove wall 20a extend in the tire circumferential direction while meandering in a tread surface view. In the tread surface view, the groove wall 10a and the groove wall 20a are symmetrical with respect to a straight line passing through the center of the groove width of the main groove 50 in the tread width direction and along the tire circumferential direction. In the present embodiment, a straight line passing through the center in the tread width direction of the groove width of the main groove 50 and along the tire circumferential direction coincides with the tire equator line CL.

(1.2.2) Groove Width The groove width of the main groove 50 changes at a predetermined cycle along the tread width direction. Therefore, the groove width of the main groove 50 changes periodically as it advances in the tire circumferential direction. For this reason, the groove wall 10a and the groove wall 20a are wavy in the tread surface view. The groove width of the main groove 50 is a groove width along the tread width direction, and indicates a distance in the tread width direction from an arbitrary point on the groove wall 10a to the groove wall 20a.

The ratio W _MIN / W _MAX between the minimum width portion W _MIN of the groove width of the main groove 50 and the maximum width portion W _MAX of the groove width of the main groove 50 is in the range of 35% to 85%.

(1.2.3) Projection 70
As shown in FIGS. 1 and 2, a bottom portion 50 btm that is a groove bottom of the main groove 50 is formed with a protruding portion 70 that protrudes outward in the tire radial direction and extends in the tire circumferential direction. In the tread surface view, the protrusions 70 are arranged symmetrically in the tread width direction with the tire equator line CL as the axis of symmetry.

  The protrusion part 70 has the protrusion part 70a arrange | positioned on the tire equator line CL. In addition, the protruding portion 70 includes a protruding portion 70b adjacent to the protruding portion 70a and a protruding portion 70c adjacent to the protruding portion 70b.

  The protrusion 70a extends along the tire equator line CL. Accordingly, the protrusion 70a is formed in a straight line. The protrusion 70b and the protrusion 70c extend in the tire circumferential direction while meandering in a tread surface view. That is, the protrusion part 70b and the protrusion part 70c are wavy in the tread surface view. The protrusion part 70b and the protrusion part 70c are extended in the tire circumferential direction according to the groove wall 10a or the groove wall 20a with a short distance. In other words, the protrusion 70b and the protrusion 70c extend in the tire circumferential direction along the groove wall 10a or the groove wall 20a. For this reason, it forms so that the space | interval of the tread width direction of the groove wall 10a, the groove wall 20a, and the projection part 70 may become equal. Therefore, in FIG. 2, for example, the tread width direction interval between the groove wall 10a and the protrusion 70c is equal to the tread width direction interval between the protrusion 70c and the protrusion 70b. The same applies to other cases. The protrusion 70 is formed over the entire tire circumferential direction of the main groove 50.

  In the cross section along the tread width direction and the tire radial direction, the protrusion 70 has a triangular shape having a vertex on the outer side in the tire radial direction. Therefore, the width of the protrusion 70 in the tread width direction becomes smaller as it goes outward in the tire radial direction. The height h of the protrusion, which is the height from the bottom 50 btm to the tire radial direction outer end of the protrusion 70, is the height from the bottom 50 btm to the tread surface contacting the road surface, that is, the land portion (land portion 10, land portion). 20, smaller than the height H of the land portion 30). In the present embodiment, the height h of the protrusion 70 is the same for any protrusion. The height h of the protrusion 70 is preferably 15% or less of the height H of the land portion. Specifically, in a general passenger car, the height h of the protrusion is preferably 1 mm or less. Moreover, in order to acquire the effect of this invention, it is preferable that it is 0.7 mm or more. The width d of the protrusion 70 in the tread width direction is preferably 1 mm or less so as not to hinder drainage performance. The width d in the tread width direction of the protrusion 70 is the width at the bottom 50 btm.

(1.2.4) Amplitude and Period of Main Groove 50 As shown in FIG. 3, the groove width of the main groove 50 varies with the period λ along the tire circumferential direction. The groove wall 10a and the groove wall 20a have an amplitude a along the tread width direction.

The groove wall 10a and the groove wall 20a change with a period λ along the tire circumferential direction in the tread surface view. The groove wall 10a and the groove wall 20a are provided in a symmetrical shape on the front side and the rear side with the maximum width portion W _MAX as a boundary when the minimum width portion W _MIN is the starting point of the period λ.

  The relationship between the period a in the tire circumferential direction in the groove width of the main groove 50 and the period λ, which is the period in the tire circumferential direction of the groove wall 10a and the groove wall 20a, and the amplitude a is as follows. ~ 100 times.

  The relationship between the tread length, which is the length in the tire circumferential direction of the tread that contacts the road surface during rolling of the tire, and the cycle λ of the main groove 50 is 0.5 to 20 times the cycle λ.

(1.3) Action / Effect As described above, according to the pneumatic tire 1 according to the present embodiment, the main groove 50 has a flow that is a flow of water along the groove wall 10a and the groove wall 20a. Line _S10a and streamline _S20a are generated. The water flowing along the groove wall 10a and the groove wall 20a passes through the maximum width portion W _MAX and then decreases in the stream width S _10a and the stream line S _{20a in} the minimum width portion W _MIN as the groove width of the main groove 50 decreases. Drained in the direction of the extension line.

  Further, according to such a pneumatic tire 1, the groove width of the main groove 50 in the tread width direction changes with the period λ, so that the water flowing in the main groove 50 changes the width in the tread width direction with the period λ. While flowing.

That is, the water in the main groove 50 pulsates with a period λ and is drained in the direction of the extension of the stream line S _10a and the stream line S _20a in the minimum width portion W _MIN .

Here, since the pneumatic tire 1 has the protrusion 70, the streamline _S10a and the streamline _S20a are easy to flow along the protrusion 70 as shown in FIG. For this reason, it becomes difficult for the streamline _S10a and the streamline _S20a to collide, and generation | occurrence | production of a turbulent flow is suppressed. Thereby, drainage performance can be improved.

  Since the bottom portion 50btm is formed with a protrusion 70 that protrudes outward in the tire radial direction and extends in the tire circumferential direction, the pebbles are prevented from directly hitting the bottom portion 50btm. For this reason, it can suppress that a crack generate | occur | produces in a groove bottom.

  In the present embodiment, the protrusions 70 are arranged symmetrically in the tread width direction with the tire equator line CL as the axis of symmetry. Furthermore, the protrusion part 70 has the protrusion part 70a arrange | positioned on the tire equator line CL. For this reason, since the flow of the water flowing through the main groove 50 is uniform around the tire equator line CL, the drainage performance is further improved.

  In the present embodiment, the width of the protrusion 70 in the tread width direction becomes smaller as it goes outward in the tire radial direction. For this reason, even if it provides the projection part 70, since the reduction | decrease of the volume of a main groove decreases, the fall of the amount of drainage can be suppressed. For this reason, the drainage performance is further improved as a whole.

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

  In the embodiment described above, the groove wall 10a and the groove wall 20a meander repeatedly along the tire circumferential direction in the tread surface view, but the groove wall 10a and the groove wall 20a do not need to meander repeatedly. For example, a part may be provided linearly along the tire circumferential direction.

In the above-described embodiment, the groove wall 10a and the groove wall 20a change at a predetermined repetition period along the tire circumferential direction in the tread surface view, and within one period, when the maximum width portion _WMAX is a boundary, The front side and the rear side are provided in a symmetrical shape. However, the groove wall 10a and the groove wall 20a do not need to be provided in a symmetrical shape on the front side and the rear side when the maximum width portion W _MAX is a boundary in one cycle. In this case, the groove width may be provided so as to be abruptly narrowed.

  In the above-described embodiment, the tire equator line CL is the axis of symmetry, but this is not necessarily the case. When the center of the groove width of the main groove 50 in the tread width direction does not coincide with the tire equator line CL, the tire equator line CL is not a symmetric axis, and another straight line along the tire circumferential direction is a symmetric axis. It becomes.

  In the embodiment described above, the groove wall 10a, the groove wall 20a, and the protrusion 70 are formed so that the intervals in the tread width direction are equal, but the present invention is not limited to this. The intervals in the tread width direction of the groove wall 10a, the groove wall 20a, and the protrusion 70 may be different. For example, the interval in the tread width direction between the protrusion 70c and the protrusion 70b may be larger than the interval in the tread width between the groove wall 10a and the protrusion 70c.

  In the embodiment described above, the height h of the protrusion 70 is the same in any protrusion, but is not limited thereto. You may change the height h of each projection part 70 as needed. For example, the height h of the protrusion 70 may be increased as it goes toward the groove wall. Thereby, since the water which flows along the groove wall 10a or the groove wall 20a flows along the protrusion part 70 more, it becomes difficult to generate | occur | produce a turbulent flow.

  In the embodiment described above, in the cross section along the tread width direction and the tire radial direction, the projecting portion 70 has a triangular shape having a vertex on the outer side in the tire radial direction, but is not limited thereto. For example, as shown in FIG. 4A, the protrusion 70 may be trapezoidal in the cross section. Moreover, as shown in FIG.4 (b), as for the projection part 70, the edge part of a tire radial direction outer side may be roundish. Thereby, even if the pebble hits the protrusion 70, the outer end portion in the tire radial direction is not easily damaged. For this reason, drainage performance can be improved in the longer term.

  In the embodiment described above, the pneumatic tire 1 has the five protrusions 70, but is not limited thereto. For example, as shown in FIG. 4A, the pneumatic tire may have four protrusions 70. Further, as shown in FIG. 4B, the pneumatic tire may have three protrusions 70. In addition, the pneumatic tire may have two protrusions 70, or may have six or more protrusions 70. The number of the protrusions 70 is appropriately adjusted according to the size of the main groove in which the protrusions 70 are formed, the performance required for the pneumatic tire, and the like.

  In the embodiment described above, the protrusion 70 is formed over the entire tire circumferential direction of the main groove 50, but is not limited thereto. The protrusion 70 may be partially formed in the tire circumferential direction.

  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 ... Tire, 10, 20, 30 ... Land part, 10a, 10b, 20a, 20b, 30a ... Groove wall, 50btm ... Bottom part, 50, 60 ... Main groove, 70, 70a, 70b, 70c ... Projection part, 110 ... Lateral groove

Claims (4)

A first land portion extending in the tire circumferential direction and contacting the road surface;
A second land portion extending in the tire circumferential direction and contacting the road surface;
A main groove extending in the tire circumferential direction is formed between the first land portion and the second land portion,
The first land portion has a first groove wall that forms the main groove,
The second land portion has a second groove wall that forms the main groove,
The first groove wall and the second groove wall extend in the tire circumferential direction while meandering in a tread surface view,
The groove width of the main groove along the tread width direction is a tire that changes at a predetermined cycle along the tread width direction,
In the tread surface view, the first groove wall and the second groove wall are symmetric with respect to a straight line along the tire circumferential direction passing through the center in the tread width direction of the groove width of the main groove,
A tire in which a protruding portion that protrudes outward in the tire radial direction and extends in the tire circumferential direction is formed at a groove bottom of the main groove.   The tire according to claim 1, wherein the protrusions are arranged symmetrically in the tread width direction with the straight line as a symmetry axis.   The tire according to claim 1, wherein the protrusion has a protrusion arranged on the straight line.   The tire according to any one of claims 1 to 3, wherein a width of the protruding portion in the tread width direction becomes smaller toward the outer side in the tire radial direction.

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