JP2010208419A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in wet hydroplaning performance and on-snow performance. <P>SOLUTION: Inside of a center side circumferential main groove 14, a first inclined land part 34 and a second inclined land part 50 completely crossing the center side circumferential main groove 14 are arranged. Since snow that enters the center side circumferential main groove 14 is caught in them during on-snow travel, the entered snow is prevented from being shifted in the groove in the circumferential direction, and the on-snow performance is improved. Since the heights of the first inclined land part 34 and the second inclined land part 50 are gradually decreased, the main groove 14 is not completely closed, and water in a ground contact surface can be drained to the rear of a tire via the main groove 14 during wet road surface travel. Moreover, in the first inclined land part 34 and the second inclined land part 50, a part of the water that enters the main groove 14 is introduced to a first inclined lug groove 22 and a third inclined lug groove 26 and drained, therefore, drainage performance is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved wet hydroplaning performance and on-snow performance.

  As a conventional pneumatic tire, in order to aim for effective drainage with respect to a tread pattern in which a plurality of land portions extending in the tire circumferential direction are formed on a tire tread surface, lug grooves inclined with respect to the tire circumferential direction are provided. A method of connecting to the circumferential main groove is known (for example, see Patent Document 1).

JP-A-2-179508

  However, when trying to enhance the drainage effect for a tread pattern that forms a plurality of land rows on the tire tread, a groove shape and configuration that does not impede water flow are required, but it is intended to add performance on snow to this In this case, if the groove penetrates in the direction in which traction is desired (a general circumferential main groove extending in the tire circumferential direction), there is little snow catching and satisfactory on-snow performance cannot be obtained.

  The present invention has been made to solve the above problems, and an object thereof is to provide a pneumatic tire with improved wet hydroplaning performance and on-snow performance.

  The present invention has been made in view of the above-described facts, and the pneumatic tire according to claim 1 includes a tread that contacts the road surface, and a circumferential main groove that is provided on the tread and extends along the tire circumferential direction. And extending in the tire axial direction from the circumferential main groove and extending in the tire axial direction so that the end on the tire equatorial plane side contacts the front of the outer end in the tire axial direction. An inclined lug groove that inclines with respect to the slope, and a slope that extends from one land portion toward the other land portion with the circumferential main groove interposed therebetween, and that completely crosses the circumferential main groove. And a land portion.

Next, the operation of the pneumatic tire according to claim 1 will be described.
In the pneumatic tire according to claim 1, since the inclined land portion that completely traverses the circumferential main groove is disposed inside the circumferential main groove, the snow that has entered the circumferential main groove during running on the snow Since it is caught in the inclined land portion, it is possible to prevent the snow that has entered the circumferential main groove from shifting in the circumferential direction in the groove, and to improve snow performance such as snow traction performance and snow brake performance.

The inclined land portion crosses the circumferential main groove, but the height gradually decreases from one land portion to the other land portion across the circumferential main groove, so the circumferential main groove Is not completely closed, and the water in the ground contact surface can be drained to the rear of the tire through the circumferential main groove during wet running. Furthermore, since the inclined lug groove connected to the circumferential main groove is inclined in the tire axial direction and the tread pattern is a so-called directional pattern, the water in the ground contact surface and the water in the circumferential main groove A part can be drained to the outside in the tire axial direction through the inclined lug groove.
Thereby, wet hydroplaning performance and performance on snow can be improved.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, when the inclined land portion is viewed in a cross section along a direction in which the height gradually decreases, the contour shape of the inclined land portion is a central portion. Is recessed.

Next, the operation of the pneumatic tire according to claim 2 will be described.
By denting the central part of the inclined land part arranged in the circumferential main groove, an effective edge effect can be obtained when running on snow, and at the same time, a strong snow column can be formed in the circumferential main groove It is possible to improve the running performance on snow.

  Invention of Claim 3 is a pneumatic tire of Claim 1 or Claim 2, The edge part of the tire rotation direction side of the said inclined land part, and the opposite side to the tire rotation direction of the said inclined lug groove The groove wall is connected continuously without any step.

Next, the operation of the pneumatic tire according to claim 3 will be described.
In the pneumatic tire according to claim 3, a part of the water in the circumferential main groove is guided to the edge of the inclined land portion on the tire rotation direction side and heads toward the inclined lug groove. At this time, the edge of the inclined land portion on the tire rotation direction side and the groove wall surface on the opposite side to the tire rotation direction of the inclined lug groove (= the land side wall surface of the land portion on the tire rotation direction side) are continuous without a step. Therefore, part of the water in the circumferential main groove can enter the inclined lug groove more smoothly, and the drainage by the inclined lug groove is further improved.

  As described above, according to the pneumatic tire of the present invention, the wet hydroplaning performance and the on-snow performance can be improved.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. (A) is an enlarged plan view near the center of the tread, (B) is a cross-sectional view taken along line AA in FIG. 2 (A), and (C) is a cross-sectional view taken along line BB in FIG. 2 (A). FIG. It is a top view of the tread of the pneumatic tire concerning a conventional example. 5 is a plan view of a tread of a pneumatic tire according to Comparative Example 1. FIG. 5 is a plan view of a tread of a pneumatic tire according to Comparative Example 2. FIG.

Hereinafter, a pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the tread 12 of the pneumatic tire 10 of the present embodiment is provided with center side circumferential main grooves 14 extending along the tire circumferential direction on both sides of the tire equator plane CL. A shoulder side circumferential main groove 16 is disposed outside the directional main groove 14 in the tire axial direction. Reference numeral 12E denotes a ground end of the tread 12.
Center ribs 18 extending continuously in the tire circumferential direction are disposed between the pair of center-side circumferential main grooves 14, that is, on the tire equatorial plane CL. A sipe 20 that is inclined with respect to the tire axial direction is formed on the center rib 18.

In the land portion between the center side circumferential main groove 14 and the shoulder side circumferential main groove 16, a first inclined lug groove 22, a second inclined lug groove 24 having different inclination angles with respect to the tire axial direction, and the first Three inclined lug grooves 26 are sequentially formed in the tire circumferential direction, and the land portion is partitioned into a plurality of blocks.
The inclination angle (average value) with respect to the tire axial direction increases in the order of the first inclined lug groove 22, the second inclined lug groove 24, and the third inclined lug groove 26.
Here, the land portion between the first inclined lug groove 22 and the second inclined lug groove 24 is located between the first block 28, the second inclined lug groove 24 and the third inclined lug groove 26. The land portion is the second block 30, and the land portion between the third inclined lug groove 26 and the first inclined lug groove 22 is the third block 32.

As shown in FIG. 2, a first inclined land portion 34 that extends from the first block 28 toward the center rib 18 and reaches the center rib 18 is integrally formed on the tire equatorial plane side of the first block 28. Is formed.
The height of the first inclined land portion 34 gradually decreases from the first block 28 toward the center rib 18, and at the end on the center rib side, the groove bottom of the center-side circumferential main groove 14. And the same level (the height measured from the groove bottom is zero). In the present embodiment, the end portion on the tire equatorial plane side of the first inclined land portion 34 is formed so as to bite into the center rib 18.

  As shown in the sectional view of FIG. 2C, the outer surface in the tire radial direction of the first inclined land portion 34 of the present embodiment is between the tread surface of the first block 28 and the tip on the center rib 18 side. The center portion is recessed, more specifically, it is formed in a substantially arc shape having a center of curvature on the outer side of the tire.

  Further, as shown in FIG. 2A in plan view of the tread 12, an edge (side) 34 </ b> A on the tire rotation direction side (arrow R direction side) of the first inclined land portion 34 is the first block 28. The side wall surface 28A on the tire rotation direction side of the first inclined lug groove 22 is on a virtual extension line extending from the groove wall surface on the opposite side to the tire rotation direction to the tire equatorial plane side, and the first inclination The edge 34A of the land portion 34 on the tire rotation direction side and the block side wall surface 28A of the first block 28 on the tire rotation direction side are smoothly connected without any step.

  An end edge (side) 34B opposite to the tire rotation direction side of the first inclined land portion 34 is a block side wall surface 28B opposite to the tire rotation direction side of the first block 28, that is, the first side wall 34B. 2 on the imaginary extension of the groove wall on the tire rotation direction side of the inclined lug groove 24 toward the tire equatorial plane side, and the edge 34B opposite to the tire rotation direction side of the first inclined land portion 34 and the first The first block 28 is smoothly connected to the block side wall surface 28B opposite to the tire rotation direction side without any step.

The second block 30 has a substantially triangular shape in a tread plan view, and an inclined surface (chamfer) 36 is formed at each end on the acute angle side. A sipe 36 extending substantially in the tire axial direction is formed in the second block 30.
In the third block 32, inclined surfaces (chamfers) 38 are respectively formed at the end portion on the tire equatorial plane side and the end portion on the outer side in the tire width direction. Further, a sipe 40 extending substantially in the tire axial direction is formed in the third block 32. The third block 32 has an end on the outer side in the tire axial direction arranged near the center in the width direction of the shoulder side circumferential main groove 16.

  As shown in FIG. 1, the land portion 41 on the outer side in the tire axial direction of the shoulder side circumferential main groove 16 has a fourth inclined lug groove 42 and a fifth inclined lug groove 44 that are inclined with respect to the tire axial direction. Are alternately formed in the tire circumferential direction. The fourth inclined lug groove 42 opens in the shoulder side circumferential main groove 16, and the fifth inclined lug groove 44 does not open in the shoulder side circumferential main groove 16. Further, in the land portion on the outer side in the tire axial direction of the shoulder side circumferential main groove 16, a sipe 46 substantially parallel to these lug grooves is interposed between the fourth inclined lug grooves 42 and the fifth inclined lug grooves 44. , 48 are formed.

As shown in FIG. 2, the center rib 18 is integrally formed with a second inclined land portion 50 that extends from the center rib 18 toward the third block 32 and reaches the third block 32. . The second inclined land portion 50 gradually decreases in height and width from the center rib 18 toward the third block 32, and the end on the third block side is the third inclined lug groove 26. The end portion is at the same level as the groove bottom of the third inclined lug groove 26 (the height measured from the groove bottom is zero). In the present embodiment, a portion of the second inclined land portion 50 on the outer side in the tire axial direction is formed so as to be in contact with the block side wall surface of the third block 32 on the tire rotation direction side.
As shown in FIG. 2A in plan view of the tread 12, an edge (side) 50 </ b> A on the tire rotation direction side (arrow R direction side) of the second inclined land portion 50 is a third block 32. It is smoothly connected to the block side wall surface 32A on the tire rotation direction side without any step.

(Function)
In the pneumatic tire 10 of the present embodiment, the first inclined land portion 34 and the second inclined land portion 50 that completely cross the center-side circumferential main groove 14 are provided inside the center-side circumferential main groove 14. Therefore, when the snow travels, the snow that has entered the center-side circumferential main groove 14 is caught by the first inclined land portion 34 and the second inclined land portion 50, and therefore enters the center-side circumferential main groove 14. The snow is prevented from shifting in the circumferential direction in the groove, and snow performance such as snow traction performance and snow brake performance can be improved.

  In the shoulder side circumferential main groove 16 as well, the end of the third block 32 is disposed near the center in the width direction, so that the snow that has entered the shoulder side circumferential main groove 16 when traveling on snow is the third. Since it is caught by the end of the block 32, the snow that has entered the shoulder side circumferential main groove 16 is prevented from shifting in the circumferential direction in the groove, and snow performance such as snow traction performance and snow brake performance can be improved.

  Further, as shown in FIGS. 2 (B) and 2 (C), the first inclined land portion 34 and the second inclined land portion 50 are recessed in a circular arc shape, which is effective when traveling on snow. As a result, a strong snow column can be formed in the center-side circumferential main groove 14, and the running performance on snow can be improved.

  The first inclined land portion 34 and the second inclined land portion 50 completely cross the center-side circumferential main groove 14, but the height gradually decreases from one land portion to the other land portion. Therefore, the center side circumferential main groove 14 is not completely closed at the time of ground contact, and the water in the ground surface can be drained to the tire rear via the center side circumferential main groove 14 when traveling on a wet road surface. it can. Since this pneumatic tire 10 rotates in the direction of arrow R in FIG. 2, the water in the groove flows in the direction opposite to the direction of arrow R when traveling on a wet road surface.

Further, the first inclined lug groove 22, the second inclined lug groove 24, and the third inclined lug groove 26 connected to the center-side circumferential main groove 14 are inclined in the tire axial direction to be directed to the tread pattern. Therefore, the first inclined lug groove 22, the second inclined lug groove 24, and the third It is possible to drain to the outside in the tire axial direction through the inclined lug groove 26. The water discharged from the first inclined lug groove 22, the second inclined lug groove 24, and the third inclined lug groove 26 is discharged to the tire rear side via the shoulder side circumferential main groove 16, A part is discharged to the outside of the ground contact end 12 </ b> E through the fourth inclined lug groove 42.
Thereby, the pneumatic tire 10 of this embodiment can improve wet hydroplaning performance and on-snow performance.

  Furthermore, in the pneumatic tire 10 of the present embodiment, a virtual inclined lug groove in which the first inclined lug groove 22 is extended toward the tire equatorial plane CL side on the center side circumferential main groove 14 side of the first block 28. The first inclined land portion 34 is disposed on the opposite side to the tire rotating direction of the tire, and the edge (side) 34A on the tire rotating direction side (arrow R direction side) of the first inclined land portion 34 and the first Since the block side wall surface 28A on the tire rotation direction side of the block 28 is smoothly connected without a step, a part of the water in the center-side circumferential main groove 14 is partly moved to the first inclined land portion when traveling on a wet road surface. 34 can be effectively guided to the first inclined lug groove 22, and a part of the water in the center-side circumferential main groove 14 smoothly enters the first inclined lug groove 22.

  The center-side circumferential main groove 14 extends from the center rib 18 toward the third block 32 and extends to contact the block side wall surface of the third block 32 on the tire rotation direction side. Since the portion 50 is disposed, a portion of the water in the center-side circumferential main groove 14 is effectively guided to the third inclined lug groove 26 by the second inclined land portion 50 when traveling on a wet road surface. Thus, part of the water in the center-side circumferential main groove 14 smoothly enters the third inclined lug groove 26. Thus, drainage is further improved by flowing part of the water in the center-side circumferential main groove 14 to the first inclined lug groove 22 and the third inclined lug groove 26.

(Test example)
In order to confirm the effect of the present invention, a tire of a conventional example, two types of tires of a comparative example, and a tire of an example to which the present invention is applied are prepared, wet hydroplaning performance, wet braking performance, dry braking performance, We compared wet steering stability performance, dry steering stability performance, snow handling stability performance, snow traction performance, and snow braking performance on a real vehicle.

Example tire: The tire described in the above embodiment.
Conventional tire: a tire having a tread pattern shown in FIG. 3, reference numerals 100 and 102 denote circumferential main grooves, reference numerals 104, 108, and 110 denote lug grooves, reference numeral 106 denotes a narrow groove, reference numeral 110 denotes a sipe, and reference numeral 112E denotes a grounding end. The inclined lug groove 104 has a groove width of 5 to 6 mm, a groove angle of 45 °, and a groove depth of 9 mm.
Tire of Comparative Example 1: A tire obtained by removing the second inclined land portion from the tire of the example (see FIG. 4. In the center side circumferential main groove 14, only the first inclined land portion 34 crosses. .).
Tire of Comparative Example 2: A tire obtained by removing the first inclined land portion from the tire of the example (see FIG. 5. Only the second inclined land portion 50 crosses in the center-side circumferential main groove 14. .).
In Examples and Comparative Examples, the groove width of the inclined lug groove is 4 to 6 mm, the groove angle is 30 to 67 ° with respect to the tire circumferential direction, and the groove depth is 8 mm.

The test method and evaluation method will be described below.
-Wet hydroplaning performance (straight forward): Feeling evaluation at the hydroplaning limit speed when passing straight on a wet road surface with a water depth of 5 mm. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the wet hydroplaning performance.

-Wet braking performance: A braking distance was measured when full braking was performed from a traveling state on a straight road surface with a water depth of 2 mm at a speed of 80 km / h. The evaluation is represented by an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the wet braking performance.

Dry braking performance: A braking distance was measured when full braking was performed from a traveling state on a dry straight road surface at a speed of 80 km / h. The evaluation is expressed as an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the dry braking performance.

-Wet maneuvering stability: Test driver's feeling evaluation when driving on a wet circuit course in various driving modes. The evaluation is expressed as an index with the conventional example being 100, and the larger the numerical value, the better the wet steering stability.

・ Dry maneuvering stability performance: Test driver's feeling evaluation when driving on a dry circuit course in various driving modes. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the dry steering stability.

・ Snow maneuvering stability performance: Comprehensive feeling evaluation of braking performance, startability, straightness, and cornering performance on a test course on a snowy road surface. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the steering stability on snow.

-Snow traction performance: Time until acceleration on snow from 10 km / h to 45 km / h was measured. The evaluation is an index display in which the reciprocal of the acceleration time of the conventional example is 100, and the larger the value, the better the snow traction performance.

Snow braking performance: The braking distance was measured when the vehicle was fully braked from the running state on the snow at a speed of 40 km / h. The evaluation is an index display in which the reciprocal of the braking distance of the conventional example is 100, and the larger the value, the better the braking performance on snow.

  In the test, the tire size was 225 / 45R17, the internal pressure was 220 kPa, and the load was an actual vehicle equivalent to two passengers.

試験の結果、本発明の適用された実施例のタイヤは、従来例、及び比較例よりも全ての項目で性能が向上していることが分かった。

As a result of the test, it was found that the performance of the tire of the example to which the present invention was applied was improved in all items as compared with the conventional example and the comparative example.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Center side circumferential main groove 16 Shoulder side circumferential main groove 18 Center rib (land part)
22 1st inclined lug groove 24 2nd inclined lug groove 26 3rd inclined lug groove 28 1st block (land part)
30 Second block (Land)
32 3rd block (Land)
34 1st slope land part 34A edge 34B edge 50 2nd slope land part

Claims (3)

A tread that touches the road surface,
A circumferential main groove provided in the tread and extending along a tire circumferential direction;
Provided in the tread, extending from the circumferential main groove toward the outer side in the tire axial direction, and with respect to the tire axial direction so that the end on the tire equatorial plane side contacts the ground before the end on the outer side in the tire axial direction An inclined lug groove that is inclined;
An inclined land portion that extends so as to gradually decrease in height from one land portion to the other land portion across the circumferential main groove, and completely crosses the circumferential main groove;
Pneumatic tire having   2. The pneumatic tire according to claim 1, wherein when the inclined land portion is viewed in a cross section along a direction in which a height gradually decreases, a contour portion of the inclined land portion has a recessed central portion.   The edge part of the tire rotation direction side of the said inclined land part and the groove wall surface on the opposite side to the tire rotation direction of the said inclined lug groove are connected continuously without a level | step difference. Pneumatic tire.

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