JP2017105467A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise performance of a pneumatic tire without sacrificing on-snow performance.SOLUTION: A pneumatic tire has: zigzag main grooves 3 having a pitch length of Pc in a center circumferential direction; zigzag main grooves 4 having the pitch length of Ps in a shoulder circumferential direction; center inclined lateral grooves 5 inclining at an angle θc; and shoulder inclined lateral grooves 6 inclining at an angle θs. The magnitude relations of the above factors are as follows: Ps>Pc and θs<θc. Both ends of the center inclined lateral grooves 5 intersect with zigzag inclined grooves 3a or 3b of the main groove 3 in the center circumferential direction, and the inclination direction of those inclined grooves 3a or 3b is different from that of the center inclined lateral groove 5. The formation number Ns of the shoulder inclined lateral groove 6 is more than that number Nc of the center inclined lateral groove 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire that can exhibit excellent noise performance.

  For example, in winter tires that run on snowy roads such as snow tires, a block pattern is generally employed to improve snow performance. However, with such block pattern tires, there is a problem that pitch noise and pumping noise when traveling on a paved road surface are increased and noise performance is lowered.

  On the other hand, the thing of the following patent document 1 is known as a pneumatic tire which improved noise performance. As shown in FIG. 4, this tire has a center circumferential main groove a disposed on both sides of the tire equator C, a shoulder circumferential main groove b, and a center circumferential main groove a, a disposed on the outer side thereof. A transverse transverse center d, a middle transverse groove e transverse between the center transverse groove d and the shoulder circumferential main groove b, and a shoulder transverse groove f transverse between the shoulder circumferential main groove b and the tread end Te are provided. Each of the circumferential main grooves a and b is a rectangular wave-shaped zigzag groove, the amplitude and groove width of each zigzag groove, the number of transverse grooves that intersect with one zigzag groove in the ground plane, and the groove width of the transverse groove By regulating the pitch length between the lateral grooves, the mud performance or the snow performance is improved while suppressing the deterioration of the noise performance.

  However, with the recent demand for higher performance in the market, further improvement in noise performance is strongly desired.

JP 2012-11981

  Therefore, an object of the present invention is to provide a pneumatic tire with further improved noise performance without sacrificing snow performance or the like.

The present invention provides a tread portion having a center circumferential main groove disposed on both sides of the tire equator, a shoulder circumferential main groove disposed on the outer side in the tire axial direction of the center circumferential main groove, and the center circumferential main groove. A pneumatic engine comprising: a center inclined transverse groove that intersects the tire axial direction at an angle θc; and a shoulder inclined transverse groove that intersects the shoulder circumferential main groove and the tread end at the angle θs with respect to the tire axial direction. Tire,
The center circumferential main groove and the shoulder circumferential main groove are each composed of a zigzag groove in which an inclined groove portion inclined to one side in the tire axial direction and an inclined groove portion inclined to the other side are alternately repeated,
And the zigzag pitch length Ps of the shoulder circumferential main groove is made smaller than the zigzag pitch length Pc of the center circumferential main groove,
Both end portions of the center inclined lateral groove intersect with the inclined groove portion of the center circumferential main groove, respectively, and the inclined direction of the inclined groove portion is different from the inclined direction of the center inclined horizontal groove,
An angle θs of the shoulder inclined horizontal groove is smaller than an angle θc of the center inclined horizontal groove,
In addition, the number Ns of shoulder inclined lateral grooves formed is larger than the number Nc of center inclined lateral grooves formed.

  In the pneumatic tire according to the present invention, it is preferable that an inner end portion in the tire axial direction of the shoulder inclined groove intersects with a zigzag bent portion of the shoulder circumferential main groove.

The pneumatic tire according to the present invention includes a middle inclined lateral groove that crosses between the center circumferential main groove and the shoulder circumferential main groove at an angle θm with respect to the tire axial direction,
The middle inclined lateral groove has an inner end portion in the tire axial direction intersecting with a zigzag bent portion of the center circumferential main groove, and an outer end portion in the tire axial direction intersecting with a zigzag bent portion of the shoulder circumferential main groove. Is preferred.

  In the pneumatic tire according to the present invention, the inclined groove portion of the shoulder circumferential main groove has a first inclined groove portion having a small length and a first length having a large length that is alternately arranged with the first inclined groove portion. Preferably, the middle inclined groove lateral groove is connected to the first inclined groove portion in a straight line.

In the present invention, the “tread end” is the most tire axis when a normal load is loaded on a normal rim that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to the plane with a camber angle of 0 °. It means the ground contact position outside the direction. The “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, “Standard rim” for JATMA and “Design for TRA”. “Rim” or “Measuring Rim” for ETRTO. The “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based.
“Maximum air pressure”, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA, “INFLATION PRESSURE” for ETRTO. The “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” indicates “maximum load capacity”, and TRA indicates “TIRE LOAD”. The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  In the present invention, as described above, the center circumferential main groove and the shoulder circumferential main groove are formed as zigzag grooves. By arranging many zigzag grooves in this way, the edge effect is enhanced and the snow performance is improved without adversely affecting the noise performance.

  In addition, the zigzag pitch length Ps of the shoulder circumferential main groove is smaller than the zigzag pitch length Pc of the center circumferential main groove. Thereby, the zigzag number (zigzag pitch number) of the shoulder circumferential direction main groove is increased, and the edge component length in the tire axial direction can be increased. Therefore, the edge effect is enhanced on the shoulder side having a large influence on the snow performance, and the snow traction can be increased. Further, as the number of zigzags in the shoulder circumferential main groove increases, the rigidity on the shoulder side decreases, and the pattern noise can be reduced.

  Further, both end portions of the center inclined horizontal groove intersect with the inclined groove portion of the center circumferential main groove, and the inclination direction of the inclined groove portion is different from the inclination direction of the center inclined horizontal groove. Thereby, a pitch variation effect is born and pattern noise can be reduced.

  Further, the angle θs of the shoulder inclined horizontal groove is set to be smaller than the angle θc of the center inclined horizontal groove. As a result, the edge effect is enhanced on the shoulder side having a large influence on snow performance, and snow traction can be increased. On the other hand, when the angle θs is small, the noise performance is deteriorated. However, when the angle θc of the center inclined lateral groove is large, the deterioration of the noise performance can be compensated.

  Further, the number Ns of shoulder inclined lateral grooves formed is larger than the number Nc of center inclined lateral grooves formed. That is, by increasing the formation number Ns, the edge component length in the tire axial direction can be increased, and the edge effect is enhanced on the shoulder side having a large influence on the snow performance, so that the snow traction can be increased. . Further, as the number Ns of formation increases, the rigidity on the shoulder side decreases, and the pattern noise can be reduced.

  These effects cooperate with each other, and it is possible to exhibit excellent noise performance without sacrificing snow performance.

It is an expanded view which shows the tread pattern of the pneumatic tire of one Embodiment of this invention. FIG. 2 is an enlarged view showing a middle region and a shoulder region in FIG. 1. It is an enlarged view which shows the center area | region in FIG. It is an expanded view which shows the tread pattern which shows a prior art.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment is disposed in the tread portion 2 at the center circumferential main grooves 3 and 3 disposed on both sides of the tire equator C, and on the outer side in the tire axial direction. Shoulder circumferential main grooves 4 and 4 are provided.

  The tread portion 2 includes a plurality of center inclined lateral grooves 5 that cross the center area Yc between the center circumferential main grooves 3 and 3, and a shoulder area Ys between the shoulder circumferential main groove 4 and the tread end Te. A plurality of shoulder-inclined lateral grooves 6 that traverse are arranged. Accordingly, the center area Yc is divided into a plurality of center blocks Bc, and the shoulder area Ys is divided into a plurality of shoulder blocks Bs. Further, in this example, the tread portion 2 is provided with a middle inclined lateral groove 7 that crosses the middle area Ym between the center circumferential main groove 3 and the shoulder circumferential main groove 4, whereby the middle area Ym is divided into a plurality of middle areas Ym. It is divided into middle blocks Bm.

  In this example, the case where the pneumatic tire 1 is formed as a snow tire is shown.

  As shown in FIG. 2, the center circumferential main groove 3 is formed as a zigzag groove in which an inclined groove portion 3a inclined to one side in the tire axial direction and an inclined groove portion 3b inclined to the other side are alternately repeated. . A portion where the inclined groove portion 3a and the inclined groove portion 3b intersect is referred to as a zigzag bent portion 3c.

  Similarly, the shoulder circumferential main groove 4 is formed as a zigzag groove in which an inclined groove portion 4a inclined to one side in the tire axial direction and an inclined groove portion 4b inclined to the other side are alternately repeated. A portion where the inclined groove portion 4a and the inclined groove portion b intersect is referred to as a zigzag bent portion 4c.

The groove width and groove depth of the center circumferential main groove 3 and the shoulder circumferential main groove 4 can be variously determined according to common practice. However, when the groove width and / or the groove depth is reduced, the snow performance and the wet performance tend to be lowered, and conversely, when the groove width and / or the groove depth is increased, the steering stability on the dry road surface is lowered. Therefore, the groove width is preferably 3 to 9% of the tread width TW (shown in FIG. 1), and the groove depth is preferably 6 to 16 mm. In this example, the groove width W4 of the shoulder circumferential main groove 4 having a large influence on the snow performance is made larger than the groove width W3 of the center circumferential main groove 3, and the snow performance is enhanced within a limited land ratio. ing. When the groove width changes partially, the groove widths W3 and W4 are defined by the average value of the maximum width and the minimum width. Regarding the groove depth, the center circumferential main groove 3 and the shoulder circumferential main groove 4 have the same depth.

  The shoulder circumferential direction main groove 4 has a zigzag pitch length Ps set smaller than the zigzag pitch length Pc of the center circumferential direction main groove 3. As a result, the middle region Ym extends in the tire circumferential direction while increasing or decreasing the region width. In the center region Yc, the center circumferential direction main grooves 3 are arranged in parallel at substantially the same phase, so that the region width is substantially constant. When the pitch lengths Ps and Pc are changed by a variable pitch method or the like, values obtained by dividing the tire circumferential length (circumferential length) at the tire equator C by the number of zigzag pitches are respectively pitch lengths Ps and Pc. It is defined as

  Thus, by setting Ps <Pc, the zigzag number of the shoulder circumferential main grooves 4 can be increased, and the edge component length in the tire axial direction can be increased. Therefore, the edge effect is enhanced on the shoulder side having a large influence on the snow performance, and the snow traction can be increased. Further, by increasing the number of zigzags in the shoulder circumferential main groove 4, the rigidity on the shoulder side is reduced, and pattern noise caused by zigzags can be reduced.

  The pitch length Ps is not particularly limited as long as it is smaller than 1.0 times the pitch length Pc, but is preferably 1 / 1.5 times or less, and more preferably 1/2 times or less in view of the above effects. .

  In the shoulder circumferential main groove 4, one of the inclined groove portions 4a and 4b (in this example, the inclined groove portion 4b) is formed as a first inclined groove portion 8 having a small length, and the other (in this example, the inclined groove portion 4a). ) Is formed as the second inclined groove portion 9 having a large length. Further, the second inclined groove portion 9 (inclined groove portion 4a) of the present example is disposed substantially parallel to one of the inclined groove portions 3a and 3b (in the present example, the inclined groove portion 3a) in the center circumferential main groove 3. As a result, the middle region Ym has a substantially constant width between the inclined groove portions 3a and 4a, which is advantageous for steering stability. Note that the term “substantially parallel” includes a case where the second inclined groove portion 9 and the inclined groove portion 3a are inclined at an angle of 5 ° or less.

  The zigzag amplitude J3 of the center circumferential main groove 3 and the zigzag amplitude J4 of the shoulder circumferential main groove 4 are not particularly restricted, but the amplitude J4 is preferably 0.75 to 1.5 times the amplitude J3. . If it is out of this range, it will be disadvantageous for uneven wear in the middle region Ym. When the amplitudes J3 and J4 change, the amplitudes J3 and J4 are specified by the average value of the maximum width and the minimum width, respectively.

  Next, the shoulder inclined lateral groove 6 is inclined at an angle θs with respect to the tire axial direction, and the inner end of the tire axial direction intersects with the bent portion 4 c of the shoulder circumferential main groove 4. That is, the bent portion 4 c is interposed between the groove wall surfaces of the shoulder inclined lateral groove 6.

  On the other hand, as shown in FIG. 3, the center inclined lateral groove 5 is inclined at an angle θc with respect to the tire axial direction, and both ends thereof are inclined groove portions 3 a or 3 b ( In this example, it intersects with the inclined groove 3b). That is, the bent portion 3 c is not interposed between the groove wall surfaces of the center inclined lateral groove 5. The inclination direction of the inclined groove portion 3 b where the center inclined horizontal groove 5 intersects is different from the inclination direction of the center inclined horizontal groove 5. Thereby, the pitch variation effect is produced by the zigzag of the center circumferential main groove 3 and the center inclined lateral groove 5, and the pattern noise can be reduced on the center side.

Moreover, the angle θs is set smaller than the angle θc. As a result, the edge effect is enhanced on the shoulder side having a large influence on snow performance, and snow traction can be increased. On the other hand, when the angle θs is small, the noise performance is deteriorated. However, when the angle θc of the center inclined lateral groove 5 is large, the deterioration of the noise performance can be compensated. In particular, the angle θs is preferably in the range of 5 to 14 °, and if it is less than 5 °, it becomes difficult for the center inclined lateral groove 5 to compensate for the deterioration of the noise performance. Conversely, if θs exceeds 14 °, an increase in snow traction cannot be expected. Further, the angle θc is preferably 15 ° or more, and more preferably in the range of 20 to 40 °. When the angle θc is less than 15 °, improvement in noise performance cannot be expected.

  As shown in FIG. 2, the middle inclined lateral groove 7 is inclined at an angle θm with respect to the tire axial direction, and the inner end portion in the tire axial direction intersects with the bent portion 3 c of the center circumferential main groove 3. That is, the bent portion 3 c is interposed between the groove wall surfaces of the middle inclined lateral groove 7. Further, the outer end portion in the tire axial direction of the middle inclined lateral groove 7 intersects with the bent portion 4 c of the shoulder circumferential main groove 4. That is, the bent portion 4 c is interposed between the groove wall surfaces of the middle inclined lateral groove 7. The inclination direction of the middle inclined horizontal groove 7 is different from the inclination direction of the center inclined horizontal groove 5.

  Here, during running on a snowy road, in the zigzag groove, the snow is strongly compressed at the bent portion which is the end position in the length direction of the inclined groove portion. Therefore, as in this example, the inner end and the outer end of the middle inclined lateral groove 7 are connected to the bent portions 3c and 4c, so that the snow column in the center circumferential main groove 3 and the shoulder circumferential main groove The snow column in 4 and the snow column in the middle inclined lateral groove 7 can cooperate to form a strong tree-shaped snow column. That is, snow traction can be increased. Similarly, the inner end of the shoulder inclined horizontal groove 5 is connected to the bent portion 4c, so that the snow column in the shoulder circumferential main groove 4 and the snow column in the shoulder inclined horizontal groove 6 cooperate. A strong tree-like snow column can be formed. That is, snow traction can be increased.

  In this example, the middle inclined groove lateral groove 7 is linearly connected to the first inclined groove portion 8 of the shoulder circumferential main groove 4. As a result, the ability to remove snow is enhanced, which is advantageous for snow performance.

  In the pneumatic tire 1, the number Ns of shoulder inclined lateral grooves 6 formed in one shoulder region Ys is set larger than the number Nc of center inclined lateral grooves 5 formed. In this example, the case where the formation number Ns is twice the formation number Nc is shown.

  In this way, by setting Ns> Nc, the edge component length in the tire axial direction due to the shoulder inclined lateral groove 6 can be increased. That is, the edge effect is enhanced on the shoulder side having a large influence on snow performance, and snow traction can be increased. Further, as the number Ns of formation increases, the rigidity on the shoulder side decreases, and pattern noise caused by the zigzag and shoulder inclined lateral grooves 6 can be reduced.

  In this example, a siping 20 is formed in the center block Bc, the middle block Bm, and the shoulder block Bs to ensure grip on the ice road surface.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to illustrated embodiment, It can deform | transform and implement in a various aspect.

A snow tire of size 265 / 70R17 having the basic pattern of FIG. Each test tire was tested for snow performance and noise performance. The common specifications and test methods for each test tire are as follows.
Wearing rim: 17 x 7.5
Tire internal pressure: 220kPa
Test vehicle: displacement 2400cc, four-wheel drive vehicle Tire mounting position: all wheels

<Snow performance>
The traction when driving on a snowy road with the test vehicle was evaluated by the driver's sensuality. A result is a score which sets the comparative example 1 to 100, and shows that snow performance is excellent, so that a numerical value is large.

<Noise performance>
The tire was run on a drum at a speed of 80 km / h, and the noise level due to the pattern noise at that time was measured. And the comparative example 1 was made into the reference value, and it evaluated by the difference. The minus (minus) notation is smaller than the reference value and indicates excellent noise performance.

  As shown in the table, it can be confirmed that the embodiment can improve the noise performance while maintaining high snow performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Center circumferential direction main groove 3a, 3b Inclination groove part 3c Bending part 4 Shoulder circumferential direction main groove 4a, 4b Inclination groove part 4c Bending part 5 Center inclination side groove 6 Shoulder inclination side groove 7 Middle inclination side groove 8 1st Inclined groove 9 Second inclined groove

Claims (5)

A center circumferential main groove disposed on both sides of the tire equator in the tread portion, a shoulder circumferential main groove disposed on the outer side in the tire axial direction of the center circumferential main groove, and the center circumferential main groove between the center circumferential main grooves. A pneumatic tire comprising a center inclined lateral groove that intersects the direction at an angle θc, and a shoulder inclined lateral groove that intersects the shoulder circumferential direction main groove and the tread end at an angle θs with respect to the tire axial direction,
The center circumferential main groove and the shoulder circumferential main groove are each composed of a zigzag groove in which an inclined groove portion inclined to one side in the tire axial direction and an inclined groove portion inclined to the other side are alternately repeated,
And the zigzag pitch length Ps of the shoulder circumferential main groove is made smaller than the zigzag pitch length Pc of the center circumferential main groove,
The pneumatic tire according to claim 1, wherein the number Ns of shoulder inclined lateral grooves is larger than the number Nc of center inclined lateral grooves.   2. The pneumatic according to claim 1, wherein both end portions of the center inclined lateral groove intersect with the inclined groove portion of the center circumferential main groove, and the inclined direction of the inclined groove portion is different from the inclined direction of the center inclined horizontal groove. tire.   The pneumatic tire according to claim 1, wherein an angle θs of the shoulder inclined lateral groove is smaller than an angle θc of the center inclined lateral groove.   The pneumatic tire according to any one of claims 1 to 3, wherein a groove width W4 of the shoulder circumferential main groove is larger than a groove width W3 of the center circumferential main groove.   The pneumatic tire according to any one of claims 1 to 4, wherein a zigzag amplitude J4 of the shoulder circumferential main groove is 0.75 to 1.5 times a zigzag amplitude J3 of the center circumferential main groove.

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