JP2016155396A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise performance and drainage performance in a well-balanced state, and to maintain this effect over a long period.SOLUTION: In a pneumatic tire 1, a tread part 2 is provided with at least one main groove 3 of continuously extending in the tire circumferential direction and a lateral groove 7 of extending in the crossing direction with the main groove 3. A partition wall 15 having a wall surface 17 for partitioning the lateral groove 7 and the main groove 3 and extending to the outside in the tire radial direction from the groove bottom, is provided between the lateral groove 7 and the main groove 3. A thickness t1 of the partition wall 15 is 0.7-1.3% of a tread width TW, and the partition wall 15 is also provided with a fine groove 12 for communicating the main groove 3 and the lateral groove 7 and having a groove width W3 of 0.1-1.2 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire that maintains the effect of improving noise performance over a long period of time while ensuring drainage performance.

  Conventionally, as shown in FIG. 6, a main groove s extending continuously in the tire circumferential direction and a lateral groove y extending in a direction intersecting with the main groove s are provided, and between the lateral groove y and the main groove s. In addition, there has been proposed a pneumatic tire provided with a partition wall k having a small thickness that hinders communication between the lateral groove y and the main groove s. Such a partition k blocks the air column resonance in the main groove s from flowing into the horizontal groove y and ensures a large length of the horizontal groove y, so that noise performance and drainage performance are improved in a balanced manner.

  However, since this type of pneumatic tire generally has a large partition wall k and cannot be deformed flexibly, when a large force such as traction is applied, the partition wall k is easily broken due to cracks, chips, etc., and noise performance is improved. There was a problem that the effect could not be maintained for a long time. Related techniques include the following patent documents.

JP 2006-315579 A JP 2008-49791 A

  The present invention has been devised in view of the actual situation as described above, and a partition having a small thickness is provided between a lateral groove and the main groove, and a narrow groove communicating the main groove and the lateral groove is provided on the partition. The main purpose is to provide a pneumatic tire that maintains the drainage performance and maintains the noise performance improvement effect over a long period of time.

  The present invention is a pneumatic tire in which at least one main groove extending continuously in a tire circumferential direction and a lateral groove extending in a direction intersecting with the main groove are provided in a tread portion, and the main groove A partition wall having a wall surface that partitions the main groove and the lateral groove and extends from the groove bottom to the outer side in the tire radial direction is provided between the lateral grooves, and the partition wall thickness is 0.7 to 1 of the tread width. In addition, the partition wall is provided with a narrow groove that communicates the main groove and the lateral groove and has a groove width of 0.1 to 1.2 mm.

  In the pneumatic tire according to the present invention, the main groove has an outer top portion protruding outward in the tire axial direction and extends in a zigzag shape in the tire circumferential direction, and the lateral groove extends from the outer top portion of the main groove to the partition wall. The wall surface on the one side in the tire axial direction of the partition wall forms a groove wall of the main groove, and at least a part of the wall surface extends along the tire circumferential direction. It is desirable to include a circumferential portion.

  In the pneumatic tire according to the present invention, it is preferable that a tire circumferential length of the circumferential portion is larger than a tire circumferential length of the wall surface on the other side in the tire axial direction of the partition wall.

  In the pneumatic tire according to the present invention, it is preferable that the narrow groove substantially extends on an imaginary line obtained by extending the center line of the lateral groove in a plan view of the tread portion.

  In the pneumatic tire according to the present invention, the narrow groove is preferably inclined at an angle of 10 ° or more with respect to the center line of the lateral groove in a plan view of the tread portion.

  In the pneumatic tire of the present invention, the tread portion is provided with at least one main groove extending continuously in the tire circumferential direction and a lateral groove extending in a direction intersecting with the main groove, and the main groove and the lateral groove A partition wall having a wall surface that partitions the main groove and the lateral groove and extends from the groove bottom to the outer side in the tire radial direction is provided between the partition wall and the thickness of the partition wall is 0.7 to 1.3% of the tread width. It is. Such a partition blocks the air column resonance generated in the main groove and suppresses the air column resonance sound from leaking to the outside of the ground contact end, thereby improving the noise performance. Moreover, since the partition wall thickness is small, a large groove volume is ensured, and drainage performance is improved.

  The partition wall is provided with a narrow groove that communicates the main groove and the lateral groove and has a groove width of 0.1 to 1.2 mm. Such narrow grooves flexibly deform the partition against a load such as traction while ensuring the rigidity of the partition. Therefore, in the pneumatic tire of the present invention, damage such as cracks and chips is suppressed, and the partition walls are maintained over a long period of time, so that the above-described effect of improving noise performance and drainage performance is exhibited over a long period of time. .

It is an expanded view of the tread part which shows one Embodiment of this invention. It is an enlarged view of the left half of FIG. It is a perspective view explaining a partition. (A) is a top view explaining the deformation | transformation of the partition by the press of the water in a main groove, (b) is a top view explaining the tensile deformation | transformation which acts on a horizontal groove by tire rolling. (A) is a top view of the narrow groove of other embodiment of this invention, (b) is a top view of the narrow groove of other embodiment. It is an expanded view of the conventional tread part.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is suitably used as a heavy duty tire for trucks and buses, for example. The tread portion 2 is provided with at least one main groove 3 extending continuously in the tire circumferential direction, in the present embodiment, five main grooves 3 and lateral grooves 7 extending in a direction intersecting with the main grooves 3. In addition, the tire 1 of this embodiment is not limited to the thing for heavy loads, For example, the thing for passenger cars and a four-wheel drive vehicle may be used.

  The main groove 3 of the present embodiment includes one crown main groove 4 that extends closest to the tire equator C (in the present embodiment, on the tire equator C), and a pair of middle main grooves 5 provided on the outside thereof. And a pair of shoulder main grooves 6 provided on the outer sides of the middle main groove 5.

  In the present embodiment, the lateral groove 7 includes a crown lateral groove 8 extending between the crown main groove 4 and the middle main groove 5, a middle lateral groove 9 extending between the middle main groove 5 and the shoulder main groove 6, and A shoulder lateral groove 10 extending between the shoulder main groove 6 and the ground contact Te is included.

  Thereby, the tread portion 2 includes a crown land portion 11a between the crown main groove 4 and the middle main groove 5, a middle land portion 11b between the middle main groove 5 and the shoulder main groove 6, and a shoulder main groove. 6 and the shoulder land portion 11c between the ground contact end Te are separated.

  The grounding end Te is grounded on a flat surface with a normal load applied to the tire rotation shaft and a camber angle of 0 °, from a reference state in which the tire is assembled on a regular rim and filled with a regular internal pressure. It is the position on the outermost side in the tire axial direction that makes contact with the road surface. And the tire axial direction distance between this grounding edge Te and Te is defined as the tread width TW.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA, “Design Rim” for TRA, ETRTO Then "Measuring Rim". In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. It is the maximum air pressure for JATMA and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES". If ETRTO, "INFLATION PRESSURE". Furthermore, “regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”. If ETRTO, “LOAD CAPACITY”.

  The main groove 3 of the present embodiment has an outer top portion 12a protruding outward in the tire axial direction and extends in a zigzag shape in the tire circumferential direction. Such a main groove 3 serves to suppress an excessive increase in drainage resistance while disturbing air column resonance generated in the main groove 3 to improve noise performance. In addition, the middle main groove 5 and the shoulder main groove 6 of this embodiment are the said outer top part 12a, the inner top part 12b which protrudes in a tire axial direction inner side, and the linear part which joins the outer top part 12a and the inner top part 12b linearly. 12c. The crown main groove 3 is formed by an outer top portion 12a and a linear portion 12d extending between the outer top portions 12a adjacent in the tire circumferential direction. In addition, the main groove 3 is not limited to such an aspect, For example, various shapes, such as a straight groove extended linearly along a tire peripheral direction, and a wave-like groove | channel, are employable.

  In order to ensure a good balance between drainage performance and noise performance, the groove width of each main groove 3 (the groove width perpendicular to the longitudinal direction of the groove, hereinafter the same applies to other grooves) W1a to W1c are treads. The width TW is preferably 1.8 to 4.0%, and the groove depth (the groove depth D1 of the shoulder main groove 6 is shown in FIG. 3) is 15 to 20 mm. Is desirable.

  Further, it is desirable that the arrangement positions of the main grooves 3 to 6 are determined so that the water film between the land portions 11a to 11c and the road surface can be smoothly discharged. For example, the tire axial distance L1 between the amplitude center line 4G of the crown main groove 4 and the tire equator C is preferably 0 to 5% of the tread width TW. Similarly, the tire axial distance L2 between the amplitude center line 5G of the middle main groove 5 and the tire equator C is preferably 8 to 18% of the tread width TW. The tire axial distance L3 between the amplitude center line 6G of the shoulder main groove 6 and the ground contact Te is preferably 15 to 25% of the tread width TW.

  In the present embodiment, the crown lateral groove 8, the middle lateral groove 9, and the shoulder lateral groove 10 extend linearly. Such horizontal grooves 8 to 10 have low drainage resistance, and improve drainage performance and rigidity of the land portions 11a to 11c.

  In the present embodiment, the crown lateral groove 8 and the middle lateral groove 9 are inclined with respect to the tire axial direction. Further, the shoulder lateral groove 10 extends along the tire axial direction.

  The groove widths W2a to W2c of these lateral grooves 8 to 10 are desirably 2.0 to 5.5% of the tread width TW. Similarly, the depth of each lateral groove 8 to 10 (FIG. 3 shows the depth D2 of the shoulder lateral groove 10) is preferably 10 to 20 mm.

  2 and 3, the shoulder main groove 6 and the shoulder lateral groove 10 are partitioned between the shoulder main groove 6 and the shoulder lateral groove 10, and the shoulder main groove 6 and the groove bottom 6z of the shoulder lateral groove 10 are provided. A partition wall 15 (in this embodiment, a shoulder partition wall 15r) having wall surfaces 17a and 17b extending from 10z to the outer side in the tire radial direction is provided. Such a shoulder partition 15r suppresses air column resonance generated in the shoulder main groove 6 from being discharged from the ground contact Te to the outside of the vehicle. Therefore, the pneumatic performance of the pneumatic tire 1 of the present embodiment is improved.

  An outer surface 15a in the tire radial direction of the shoulder partition 15r forms a tread surface 2a. Thereby, the air column resonance sound of the shoulder main groove 6 can be further blocked, and the noise performance is improved.

  The shoulder partition 15r is formed with a thickness t1 (minimum thickness when the thickness changes) of 0.7 to 1.3% of the tread width TW. When the thickness t1 is less than 0.7% of the tread width TW, the rigidity of the shoulder partition 15r becomes excessively small, and the shoulder partition 15r is damaged early due to friction during traveling. On the other hand, when the thickness t1 exceeds 1.3% of the tread width TW, the groove volume of the shoulder lateral groove 10 is greatly reduced, so that the drainage performance is deteriorated. For this reason, the thickness t1 of the shoulder partition wall 15r is preferably 0.9% or more of the tread width TW, and preferably 1.1% or less of the tread width TW.

  In the present embodiment, the wall surface 17a on one side (inner side) in the tire axial direction of the shoulder partition wall 15r constitutes a groove wall 6x on the outer side in the tire axial direction of the shoulder main groove 6, and at least a part (the book) of the wall surface 17a. In the embodiment, all) are formed as a circumferential portion 18a extending along the tire circumferential direction. Thereby, as shown in FIG. 4A, the water in the shoulder main groove 6 presses the circumferential portion 18a (the flow of water is indicated by an arrow), and the shoulder partition 15r is moved in the tire axial direction. In order to bulge outward, the water in the shoulder lateral groove 10 is smoothly discharged toward the ground contact end Te.

  Further, the shoulder partition 15r of the present embodiment is provided in contact with the outer top portion 12a of the shoulder main groove 6. That is, the shoulder lateral groove 10 extends outward in the tire axial direction from the outer top portion 12a via the shoulder partition 15r. As described above, the shoulder partition wall 15r of the present embodiment is provided in contact with the outer top portion 12a where the water pressure in the shoulder main groove 6 acts greatly, so that the above-described bulging action is exerted greatly. Therefore, the drainage performance of the tire 1 of this embodiment is further improved.

  In order to efficiently apply the water pressure in the shoulder main groove 6 to the shoulder partition wall 15r, the angle α of the straight portion 12c of the shoulder main groove 6 with respect to the tire circumferential direction is preferably 10 to 30 °.

  A wall surface 17b on the other side (outer side) of the shoulder partition wall 15r in the tire axial direction constitutes a groove wall 10y on the inner side in the tire axial direction of the shoulder lateral groove 10 and extends along the tire circumferential direction. Thereby, the swelling effect of the above-mentioned shoulder partition 15r is further exhibited, and the drainage performance is further improved.

  The circumferential portion 18a of the shoulder partition wall 15r is preferably formed such that the tire circumferential direction length La is larger than the tire circumferential direction length Lb of the wall surface 17b of the shoulder partition wall 15r. As a result, the water flowing in the shoulder main groove 6 effectively presses the shoulder partition 15r and bulges outward in the tire axial direction. Therefore, the water in the shoulder lateral groove 10 is discharged more effectively, and the drainage performance is further improved. If the tire circumferential length La of the circumferential portion 18a is excessively larger than the tire circumferential length Lb of the wall surface 17b of the shoulder partition 15r, the inclination of the shoulder main groove 6 with respect to the tire circumferential direction of the zigzag is large. And drainage resistance increases. Accordingly, the tire circumferential length La is preferably 1.05 times or more and preferably 1.30 times or less of the tire circumferential length Lb.

  The shoulder partition 15r of the present embodiment is provided with a shoulder narrow groove 16r that allows the shoulder main groove 6 and the shoulder lateral groove 10 to communicate with each other. The shoulder narrow groove 16r flexibly deforms the shoulder partition 15r with respect to a load such as traction while securing the rigidity of the shoulder partition 15r. Therefore, the shoulder partition wall 15r of the present embodiment suppresses damages such as cracks and chips, so that the noise performance improvement effect is exhibited over a long period of time.

  In addition, a tensile deformation (shown in FIG. 4B) that widens the width of the shoulder lateral groove 10 by rolling of the vehicle, and a compression that is a deformation opposite to the tensile deformation and reduces the groove width. The deformation is repeated alternately. As a result, the shoulder partition wall 15r provided with the shoulder narrow groove 16r has a large deformation of the shoulder partition wall 15r projecting outward in the tire axial direction and dent deformation inward of the tire axial direction. Therefore, the water in the shoulder lateral groove 10 is easily discharged to the outside of the ground contact end Te, and the drainage performance is improved.

  Such a shoulder narrow groove 16r needs to be formed with a groove width W3 of 0.1 to 1.2 mm. That is, when the groove width W3 is less than 0.1 mm, the shoulder partition 15r cannot be flexibly deformed. On the other hand, when the groove width W3 exceeds 1.2 mm, the rigidity of the partition walls is excessively lowered. For this reason, the groove width W3 is preferably 0.3 mm or more, and preferably 1.0 mm or less.

  From the same viewpoint, the groove depth D3 of the shoulder narrow groove 16r is preferably 20 to 80% of the groove depth D1 of the shoulder main groove 6.

  The shoulder narrow groove 16r of the present embodiment has a longitudinal direction of the shoulder lateral groove 10 (the groove center line 10c of the shoulder lateral groove 10 (FIG. 5) from one end (the lower side in the drawing in FIG. 2) 17b1 of the other wall surface 17b in the tire circumferential direction. A first longitudinal portion 16a that extends in parallel with the shoulder main groove 6 without extending to the shoulder main groove 6, and a width direction portion 16b that extends from the end of the first longitudinal portion 16a along the wall surface 17b on the other side. A crank shape is formed which includes a second longitudinal portion 16 c extending from one end of the width direction portion 16 b in parallel with the longitudinal direction of the shoulder lateral groove 10 and communicating with the shoulder main groove 6. Such shoulder narrow grooves 16r effectively and flexibly deform the shoulder partition 15r while improving noise performance. Therefore, damage to the shoulder partition wall 15r is further suppressed, and the noise performance improvement effect is exhibited for a longer period while ensuring the drainage performance.

  It is desirable that the length Lc of the first longitudinal portion 16a and the length Ld of the second longitudinal portion 16c are the same. Thereby, the rigidity balance of the shoulder partition 15r is made uniform, and the occurrence of damage is further suppressed.

  In the present embodiment, the length Le of the width direction portion 16b extends with the same length as the tire circumferential direction length Lb of the wall surface 17b on the other side. Thereby, the flexibility of the shoulder partition 15r is ensured, and air column resonance in the shoulder main groove 6 is reliably suppressed. From such a viewpoint, the ratio Le / Lb between the length Le of the width direction portion 16b and the tire circumferential direction length Lb of the wall surface 17b on the other side is desirably 0.8 to 1.2.

  The shoulder narrow groove 16r is not limited to such an embodiment. For example, as shown in FIG. 5A, the shoulder narrow groove 16r substantially extends on an imaginary line 10c1 obtained by extending the groove center line 10c of the shoulder lateral groove 10. It may be a mode that extends. Such a shoulder narrow groove 16r increases the rigidity of the shoulder partition 15r while ensuring deformation of the partition against a load such as traction. Note that the term “substantially” refers to a mode in which the shoulder narrow groove 16r passes over 50% or more of the thickness t1 of the shoulder partition wall 15r on the virtual line 10c1 as well as the whole of the virtual line 10c1. Including.

  Further, as shown in FIG. 5B, for example, the shoulder narrow groove 16r may have an aspect in which the angle θ with respect to the groove center line 10c is inclined at 10 ° or more. Such a shoulder narrow groove 16r maintains the rigidity of the shoulder partition 15r and suppresses discharge of air column resonance in the shoulder main groove 6 to the shoulder lateral groove 10. When the angle θ is larger than 75 °, the rigidity of the shoulder partition 15r is excessively lowered, and on the contrary, cracks and chips are easily generated. For this reason, the angle θ is preferably 70 ° or less, and more preferably 65 ° or less.

  Further, in the present embodiment, as shown in FIG. 1, a crown partition wall 15s that partitions the crown lateral groove 8 and the middle main groove 5 is provided, and the middle main groove 5 and the crown lateral groove 8 are provided in the crown partition wall 15s. A crank-shaped crown narrow groove 16s that communicates is provided. Further, a middle partition 15t that partitions the shoulder main groove 6 and the middle lateral groove 9 is provided, and a linear middle narrow groove 16t that communicates the shoulder main groove 6 and the middle lateral groove 9 is provided in the middle partition 15t. As described above, the shoulder partition 15 r formed in the shoulder lateral groove 10 and the crown partition 15 s formed in the crown lateral groove 8 are provided with the crank-shaped narrow grooves 16. As a result, during straight traveling, a large air column resonance from the crown main groove 4 that forms the crown land portion 11a on which a high ground pressure acts, and an air column resonance from the shoulder main groove 6 that is easily discharged to the contact end Te side. Is effectively suppressed. The middle partition wall 15t is provided with a linear narrow groove 16. As a result, the partition wall 15t of the middle land portion 11b to which a relatively large ground pressure acts is more flexibly deformed with respect to a load such as traction, so that noise characteristics are maintained for a longer period. In the present embodiment, the partition walls 15 are provided in all the lateral grooves 7.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, it cannot be overemphasized that this invention can be changed into various aspects, without being limited to said specific embodiment. For example, the middle narrow groove 16t arranged in the middle partition 15t may have a crank shape, or each partition 15r to 15t may have a straight narrow groove 16.

A pneumatic tire of size 275 / 80R22.5 having the basic structure of the tread portion shown in FIG. 1 is prototyped based on the specifications in Table 1, and the drainage performance, noise performance and partition wall durability of each sample tire are tested. It was done. The common specifications are as follows.
Tread width TW: 210mm
Crown depth of main groove: 17.0mm
Middle main groove depth: 17.0mm
Shoulder main groove depth: 17.0mm
Crown lateral groove depth: 17.0 mm
Middle lateral groove depth: 8.0mm
Shoulder lateral groove depth: 5.0mm
Slot depth of narrow groove: 3.5mm
The test method is as follows.

<Drainage performance>
Each sample tire was mounted on all the wheels of a domestic truck (2-D car) loaded with 10 tons under the condition of a 7.50 × 22.5 rim and an internal pressure of 900 kPa. Then, the running time when running on a specific section of a test course on a wet asphalt road surface having a 5.0 mm water film was measured. The results were displayed as an index with the time of Comparative Example 1 as 100. The smaller the value, the better. Note that the loading state of the truck is not loaded.

<Noise performance>
In accordance with JASO C606-81, the above test vehicle was run on a smooth dry asphalt road test course at a speed of 70 km / h, and the overall noise level was measured with a microphone installed at the right ear position of the driver's seat. . The results were expressed as an index with Comparative Example 1 as 100. The smaller the value, the better.

<Durability of partition wall>
After running 50,000 km with the test vehicle, the partition walls of each test tire were observed with the naked eye, and the number of partition walls with cracks, tears or cracks was divided by the number of all partition walls, and the damage rate ( %) Was investigated. The smaller the value, the better.

  As a result of the test, it can be confirmed that the performance of the tire of the example is improved in a well-balanced manner compared to the comparative example, and the effect is exhibited over a long period of time. In addition, the test was performed with the tire size changed, and the same tendency as the test result was confirmed.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Main groove 7 Lateral groove 15 Partition 16 Narrow groove 17 Wall surface TW Tread width

Claims (5)

A pneumatic tire in which at least one main groove extending continuously in the tire circumferential direction and a lateral groove extending in a direction crossing the main groove are provided in the tread portion,
Between the main groove and the horizontal groove, a partition wall is provided that has a wall surface that partitions the main groove and the horizontal groove and extends outward from the groove bottom in the tire radial direction,
The partition wall has a thickness of 0.7 to 1.3% of the tread width, and the partition wall communicates with the main groove and the lateral groove and has a groove width of 0.1 to 1.2 mm. A pneumatic tire provided with a groove. The main groove has an outer top portion protruding outward in the tire axial direction and extends in a zigzag shape in the tire circumferential direction,
The lateral groove extends outward in the tire axial direction from the outer top portion of the main groove through the partition wall,
The wall surface on one side of the partition wall in the tire axial direction includes a groove wall of the main groove, and includes a circumferential portion in which at least a part of the wall surface extends along the tire circumferential direction. Pneumatic tire.   The pneumatic tire according to claim 2, wherein a tire circumferential length of the circumferential portion is larger than a tire circumferential length of the wall surface on the other side of the partition wall in the tire axial direction.   The pneumatic tire according to any one of claims 1 to 3, wherein the narrow groove substantially extends on a virtual line obtained by extending a center line of the lateral groove in a plan view of the tread portion.   The pneumatic tire according to any one of claims 1 to 3, wherein the narrow groove is inclined at an angle of 10 ° or more with respect to a center line of the lateral groove in a plan view of the tread portion.

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