JP2011093452A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire reducing noise due to a tread pattern while satisfactorily maintaining drainage performance. <P>SOLUTION: In the pneumatic tire whose front and rear installation directions when installed into a vehicle are designated, three main grooves 11-13 extended in the tire circumferential direction are disposed in a tread section 1. Among these, the center position of the center main groove 12 is arranged at a position displaced from a tire equator CL toward the outside of the vehicle. Four rows of land sections 20-50 are divided by the main grooves 11-13. Narrow grooves 31 and 41 extended in the tire circumferential direction, and a plurality of inclined grooves 32 and 42 extended outwardly in a tire width direction from the narrow grooves are disposed in two rows of center land sections 30 and 40 located on the tire equator CL in the tread section 1. The width of the center land section 30 on the outside of the vehicle is larger than the width of the center land section 40 on the inside of the vehicle. A plurality of lug grooves 22 and 52 extended in the tire width direction are respectively disposed in two row of shoulder land sections 20 and 50 located on the shoulder side of the tread section 1. These lug grooves 22 and 52 are not communicated with the main grooves 11 and 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire provided with a plurality of main grooves extending in the tire circumferential direction in a tread portion. More specifically, it is possible to reduce noise caused by a tread pattern while maintaining good drainage performance. It relates to a pneumatic tire.

  In recent years, there has been a strong demand for improving the comfort of automobiles, and noise performance related to tires is cited as one of the indices of comfort.

  Conventionally, as a pneumatic tire, four main grooves extending in the tire circumferential direction are provided in a tread portion, and five rows of land portions are partitioned by these main grooves, and a plurality of lug grooves extending in the tire width direction in the land portions. Are appropriately used (see, for example, Patent Documents 1 to 3). In such a pneumatic tire, it is possible to exhibit good drainage performance based on the main groove and the lug groove.

  In the pneumatic tire configured as described above, noise is generated due to the tread pattern, and the noise tends to increase as the number of lug grooves and main grooves increases. Here, for example, noise can be reduced by reducing the number of main grooves to suppress air column resonance caused by the main grooves. However, if the number of main grooves is reduced, drainage performance will be reduced. Therefore, it is difficult to achieve both drainage performance and noise performance.

JP 2007-230251 A JP 2008-162390 A JP 2009-101846 A

  An object of the present invention is to provide a pneumatic tire that can reduce noise caused by a tread pattern while maintaining good drainage performance.

  In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire in which the mounting direction of the tire front and back when the vehicle is mounted is provided with three main grooves extending in the tire circumferential direction in the tread portion, The center position of the center main groove is arranged at a position deviated from the tire equator toward the vehicle outer side, and four rows of land portions are defined by the main groove, and two rows of center land located on the tire equator side of the tread portion. Each of the portions is provided with one narrow groove extending in the tire circumferential direction and a plurality of inclined grooves extending outward from the narrow groove in the tire width direction, and the width of the center land portion on the vehicle outer side is set to the center land on the vehicle inner side. A plurality of lug grooves extending in the tire width direction are provided in each of the two rows of shoulder land portions located on the shoulder side of the tread portion, and these lug grooves are not disposed with respect to the main groove. It is characterized in that the passing.

  In the present invention, the number of main grooves provided in the tread portion is three, and the lug grooves in the shoulder land portion are not communicated with the main grooves, so that noise caused by the tread pattern can be reduced. . Further, the center position of the center main groove is arranged at a position shifted from the tire equator toward the vehicle outer side, and the width of the center land portion on the vehicle outer side is made larger than the width of the center land portion on the vehicle inner side. By bringing the outer main groove closer to the ground contact end side, the effect of reducing noise caused by the tread pattern can be enhanced.

  As described above, the number of main grooves provided in the tread portion is set to three and the lug grooves in the shoulder land portion are not in communication with the main grooves. However, in the present invention, two rows are provided. Each of the center land portions has one narrow groove extending in the tire circumferential direction and a plurality of inclined grooves extending from the narrow groove toward the outer side in the tire width direction, so that the drainage performance can be maintained well. Can do.

  In the present invention, in order to achieve both the drainage performance and the noise performance at a higher level, the following configuration is preferably provided. That is, the ratio Wo / Wi of the width Wo of the center land portion outside the vehicle to the width Wi of the center land portion inside the vehicle is preferably in the range of 1.15 to 1.35. The intersection angle between the narrow groove and the inclined groove is preferably in the range of 30 ° to 50 °. The main groove outside the vehicle is narrower than the main groove inside the vehicle, and the ratio Li / Lo of the width Li of the main groove inside the vehicle to the width Lo of the main groove outside the vehicle is in the range of 1.05 to 1.25. good. The amount of deviation d between the center position of the center main groove and the tire equator is preferably in the range of 5 to 100% of the width L of the center main groove.

  As described above, when the number of main grooves provided in the tread portion is three and the center main groove is disposed in the vicinity of the tire equator, steering stability may be reduced. Therefore, it is preferable that the central portion including the center main groove in the tread portion and the outer portions located on both outer sides thereof are made of different rubber compositions, and the hardness of the central portion is higher than the hardness of the outer portion. Thereby, steering stability can be maintained favorable, achieving both drainage performance and noise performance.

  In this case, the width X of the central portion is preferably in the range of 10% to 35% of the ground contact width TCW of the tread portion. The difference between the hardness of the central portion and the hardness of the outer portion is preferably in the range of 3-7. Thereby, it is possible to improve the steering stability without impairing the noise performance improvement effect. Here, the contact width of the tread portion is a dimension in the tire axial direction of the contact region measured under the measurement condition of the tire static load radius defined by the standard based on the tire. On the other hand, the hardness is a hardness at 20 ° C. and is a durometer hardness measured using a durometer (A type) defined in JIS K6253.

  In the present invention, the main groove means a groove having a groove width of 5.0 mm to 15.0 mm and a groove depth of 7.0 mm to 10.0 mm, and the narrow groove means a groove width of 1.0 mm to 3. It means a groove having a groove depth of 3.0 mm to 7.0 mm at 0 mm.

It is a top view which shows the tread pattern of the pneumatic tire which consists of embodiment of this invention. It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is a top view which shows an example of the tread pattern of the conventional pneumatic tire.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a tread pattern of a pneumatic tire according to an embodiment of the present invention. This pneumatic tire is a tire in which the mounting direction of the tire front and back when the vehicle is mounted is designated. In FIG. 1, CL is the tire equator, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted.

  As shown in FIG. 1, the tread portion 1 is formed with three main grooves 11, 12, 13 extending in the tire circumferential direction. Among them, the center main groove 12 is arranged at a position where the center position is slightly shifted from the tire equator CL to the vehicle outer side. These main grooves 11 to 13 define four rows of land portions 20, 30, 40, and 50 from the vehicle outer side toward the vehicle inner side.

  A plurality of lug grooves 22 extending in the tire width direction are formed in the shoulder land portion 20 located outside the vehicle. These lug grooves 22 end at the tire equator CL side in the shoulder land portion 20 and are not in communication with the main groove 11 on the vehicle outer side.

  The center land portion 30 located outside the vehicle has one narrow groove 31 extending in the tire circumferential direction, a plurality of inclined grooves 32 extending from the narrow groove 31 to the tire width direction outer side and communicating with the main groove 11, A plurality of notch grooves 33 extending from the narrow groove 31 inward in the tire width direction and terminating in the center land portion 30 are formed. The inclined groove 32 and the cutout groove 33 are inclined in opposite directions to form a V shape.

  The center land portion 40 located on the inner side of the vehicle has one narrow groove 41 extending in the tire circumferential direction and a plurality of inclined grooves 42 extending from the narrow groove 41 outward in the tire width direction and communicating with the main groove 13. Is formed. The width Wo of the center land portion 30 outside the vehicle is larger than the width Wi of the center land portion 40 inside the vehicle.

  The shoulder land portion 50 located inside the vehicle is formed with one narrow groove 51 extending in the tire circumferential direction and a plurality of lug grooves 52 extending in the tire width direction. The end portions on the tire equator CL side of the lug grooves 52 terminate in the shoulder land portion 50 and are not communicated with the main groove 13 on the vehicle inner side.

  In the pneumatic tire having the above-described tread pattern, the three main grooves 11 to 13 are provided in the tread portion 1 and the lug grooves 22 and 52 of the shoulder land portions 20 and 50 are not communicated with the main grooves 11 and 13. By doing so, noise caused by the tread pattern can be reduced. That is, when the number of main grooves is 3, compared to the case where the number of main grooves is 4, the air column resonance caused by the main grooves can be suppressed and noise can be reduced. Further, when the lug grooves 22 and 52 of the shoulder land portions 20 and 50 are not communicated with the main grooves 11 and 13, noise caused by the tread pattern is difficult to leak to the outside of the tire.

  Further, the center position of the center main groove 12 is arranged at a position shifted from the tire equator CL toward the vehicle outer side, and the width Wo of the center land portion 30 outside the vehicle is made larger than the width Wi of the center land portion 40 inside the vehicle. As a result, the effect of reducing noise caused by the tread pattern can be enhanced by bringing the main groove 11 on the vehicle outer side closer to the ground contact end in the tire width direction. In other words, since the contact length in the tire circumferential direction becomes shorter on the contact end side in the tire width direction, when the main groove 11 on the vehicle outer side is brought closer to the contact end side in the tire width direction, air column resonance due to the main groove 11 is suppressed. Can do. On the other hand, since the main groove 11 on the vehicle outer side has a smaller contribution to the drainage performance than the main groove 13 on the vehicle inner side, the influence on the drainage performance is small.

  In the pneumatic tire, the narrow grooves 31 and 41 extending in the tire circumferential direction in the two central land portions 30 and 40 and the plurality of inclined grooves 32 extending from the narrow grooves 31 and 41 toward the outer side in the tire width direction. , 42 are formed. Therefore, even when the three main grooves 11 to 13 are provided in the tread portion 1, the narrow grooves 31 and 41 and the inclined grooves 32 and 42 cooperate with the main grooves 11 and 13 to drain water on the road surface. By effectively eliminating it, the drainage performance can be maintained well.

  In the pneumatic tire, the ratio Wo / Wi of the width Wo of the center land portion 30 outside the vehicle to the width Wi of the center land portion 40 inside the vehicle is set in a range of 1.15 to 1.35. Thereby, both drainage performance and noise performance can be achieved at a higher level. When the ratio Wo / Wi is less than 1.15, the noise performance improving effect is lowered, and when it exceeds 1.35, the draining performance improving effect is lowered.

  In the center land portion 30 outside the vehicle, the intersection angle θo between the narrow groove 31 and the inclined groove 32 is set in a range of 30 ° to 50 °. Similarly, in the center land portion 40 inside the vehicle, the intersection angle θi between the narrow groove 41 and the inclined groove 42 is set in a range of 30 ° to 50 °. Thereby, the improvement effect of drainage performance can fully be acquired. When the crossing angles θo and θi are out of the above ranges, the drainage performance improving effect is lowered. When the inclined grooves 32 and 42 are curved, the crossing angles θo and θi are angles between a straight line connecting both ends of the center lines of the inclined grooves 32 and 42 and the center line of the narrow grooves 31 and 41.

  The main groove 11 outside the vehicle is narrower than the main groove 13 inside the vehicle, and the ratio Li / Lo of the width Li of the main groove 13 inside the vehicle to the width Lo of the main groove 11 outside the vehicle is 1.05-1. .25 is set. Thereby, both drainage performance and noise performance can be achieved at a higher level. In other words, the main groove 11 on the vehicle outer side has a relatively large influence on the noise performance, and the main groove 13 on the vehicle inner side has a relatively large influence on the drainage performance. The inner main groove 13 is widened. When the ratio Li / Lo is less than 1.05, the effect of improving the drainage performance is lowered. Conversely, when the ratio Li / Lo exceeds 1.25, the effect of improving the noise performance is lowered. It is desirable that the main groove 11 on the vehicle outer side and the main groove 13 on the vehicle inner side are both wider than the center main groove 12.

  The shift amount d between the center position of the center main groove 12 and the tire equator CL is set in a range of 5 to 100% of the width L of the center main groove 12. Thereby, both drainage performance and noise performance can be achieved at a higher level. If the shift amount d is less than 5% of the width L of the center main groove 12, the effect of improving the noise performance is reduced, and conversely if it exceeds 100% of the width L of the center main groove 12, the improvement effect of the drainage performance is reduced. .

  FIG. 2 shows a cross-sectional structure of a pneumatic tire according to an embodiment of the present invention. In FIG. 2, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. As shown in FIG. 2, a carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 is wound up around the bead core 5 embedded in each bead portion 3 from the tire inner side to the outer side. On the other hand, a plurality of belt layers 6 including reinforcing cords inclined with respect to the tire circumferential direction are disposed on the outer peripheral side of the carcass layer 4 in the tread portion 1. Further, a belt cover layer 7 including reinforcing cords oriented in the tire circumferential direction is disposed on the outer peripheral side of the belt layer 6.

  As described above, when the three main grooves 11 to 13 are provided in the tread portion 1 and the center main groove 12 is disposed in the vicinity of the tire equator CL, the rigidity of the tread portion 1 is reduced in the vicinity of the tire equator CL. In order to compensate for such a local lack of rigidity of the tread portion 1, the central portion 1A including the center main groove 12 in the tread portion 1 and the outer portions 1B located on both outer sides thereof are composed of different rubber compositions. Then, the hardness of the central portion 1A is made higher than the hardness of the outer portion 1B. Thereby, steering stability can be maintained favorable.

  Here, the width X of the central portion 1A is set to a range of 10% to 35% of the ground contact width TCW of the tread portion 1. Thereby, it is possible to improve the steering stability without impairing the noise performance improvement effect. If the width X of the central portion 1A is less than 10% of the ground contact width TCW, the steering stability improving effect is lowered, and conversely if it exceeds 35%, the noise performance improving effect is lowered.

  The difference between the hardness of the central portion 1A and the hardness of the outer portion 1B is set in the range of 3-7. Thereby, it is possible to improve the steering stability without impairing the noise performance improvement effect. If the difference in hardness between the central portion 1A and the outer portion 1B is less than 3, the improvement effect of steering stability is reduced, and if it exceeds 7, the improvement effect of noise performance is reduced. In addition, as for the hardness of the outer part 1B, it is desirable to set to the range of 55-75.

  With a tire size 215 / 50R17, as shown in FIG. 1, in a pneumatic tire in which the mounting direction of the tire front and back when the vehicle is mounted is specified, three main grooves extending in the tire circumferential direction are provided in the tread portion, The center position of the center main groove is arranged at a position deviated from the tire equator to the outside of the vehicle. These main grooves define four rows of land portions, and two rows of center land portions on the tire equator side of the tread portion. Each is provided with a single narrow groove extending in the tire circumferential direction and a plurality of inclined grooves extending from the narrow groove toward the outer side in the tire width direction. A plurality of lug grooves extending in the tire width direction are provided in each of two rows of shoulder land portions that are larger than the width and located on the shoulder side of the tread portion, and these lug grooves are not communicated with the main groove. To prepare a tire of Example 1-5.

  In Examples 1 to 5, the ratio Wo / Wi of the width Wo of the center land portion outside the vehicle to the width Wi of the center land portion inside the vehicle was set as shown in Table 1. Here, the width Wi is constant and the width Wo is changed. Further, the crossing angles θo and θi between the narrow groove and the inclined groove are each 30 °, the ratio Li / Lo of the width Li of the main groove inside the vehicle to the width Lo of the main groove outside the vehicle is 1.05, and the center main The shift amount d between the center position of the groove and the tire equator was 5% of the width L of the center main groove.

  For comparison, at tire size 215 / 50R17, as shown in FIG. 3, the tread portion (61) is provided with four main grooves (62) extending in the tire circumferential direction, and these main grooves form five rows of land portions ( 63, 64, 65, 66, 67), a plurality of notch grooves (68) are provided in the center land portion (65) located on the tire equator, and a plurality of notches are provided in the intermediate land portion (64, 66). A conventional tire having a plurality of inclined grooves (69) and a plurality of lug grooves (70) and a plurality of inclined grooves (71) provided on the shoulder land portions (63, 67) was prepared.

  About these test tires, drainage performance and noise performance were evaluated by the following test methods, and the results are also shown in Table 1.

Drainage performance:
The test tire was assembled on a wheel with a rim size of 17 × 7J and mounted on a test vehicle with a displacement of 2000 cc. The speed limit was gradually increased, and the critical speed at which the hydroplaning phenomenon occurred was measured. The evaluation results are shown as an index with the conventional example being 100. A larger index value means better drainage performance.

Noise performance:
The test tire was assembled to a wheel with a rim size of 17 × 7 J and mounted on a test vehicle having a displacement of 2000 cc. And the noise level (dB) of the 500 Hz-2500 Hz high frequency band resulting from a tread pattern was calculated | required. The evaluation results are shown by the difference from the measured value of the conventional example. A negative value means that the noise has decreased from the standard, and a positive value means that the noise has increased from the standard.

  As shown in Table 1, the tires of Examples 1 to 5 were able to reduce noise caused by the tread pattern while maintaining good drainage performance in comparison with the conventional example. In particular, good results were obtained when the ratio Wo / Wi was 1.15 to 1.35.

  Next, tires of Examples 6 to 10 having a tire size of 215 / 50R17 and employing the tread pattern of FIG.

  In Examples 6 to 10, the crossing angles θo and θi between the narrow grooves and the inclined grooves were set as shown in Table 2. The ratio Wo / Wi of the width Wo of the center land portion outside the vehicle to the width Wi of the center land portion inside the vehicle is 1.25, and the width Li of the main groove inside the vehicle relative to the width Lo of the main groove outside the vehicle is The ratio Li / Lo was 1.05, and the deviation d between the center position of the center main groove and the tire equator was 5% of the width L of the center main groove.

  About these test tires, drainage performance and noise performance were evaluated by the above test methods, and the results are also shown in Table 2.

  As shown in Table 2, the tires of Examples 6 to 10 were able to reduce noise caused by the tread pattern while maintaining good drainage performance in comparison with the conventional example. In particular, good results were obtained when the crossing angles θo and θi were 30 ° to 50 °.

  Next, tires of Examples 11 to 15 having a tire size of 215 / 50R17 and employing the tread pattern of FIG.

  In Examples 11 to 15, the ratio Li / Lo of the width Li of the main groove inside the vehicle to the width Lo of the main groove outside the vehicle was set as shown in Table 3. Here, the width Lo is constant and the width Li is changed. Further, the ratio Wo / Wi of the width Wo of the center land portion outside the vehicle to the width Wi of the center land portion inside the vehicle is 1.25, and the intersection angles θo and θi of the narrow grooves and the inclined grooves are 30 °, respectively. The deviation d between the center position of the center main groove and the tire equator was 5% of the width L of the center main groove.

  About these test tires, drainage performance and noise performance were evaluated by the above test methods, and the results are also shown in Table 3.

  As shown in Table 3, the tires of Examples 11 to 15 were able to reduce noise caused by the tread pattern while maintaining good drainage performance in comparison with the conventional example. In particular, good results were obtained when the ratio Li / Lo was 1.05 to 1.25.

  Next, tires of Examples 16 to 20 having the tire size 215 / 50R17 and employing the tread pattern of FIG.

  In Examples 16 to 20, the ratio of the shift amount d between the center position of the center main groove and the tire equator with respect to the width L of the center main groove was set as shown in Table 4. Further, the ratio Wo / Wi of the width Wo of the center land portion outside the vehicle to the width Wi of the center land portion inside the vehicle is 1.25, and the intersection angles θo and θi of the narrow grooves and the inclined grooves are 30 °, respectively. The ratio Li / Lo of the width Li of the main groove inside the vehicle to the width Lo of the main groove outside the vehicle was 1.05.

  About these test tires, drainage performance and noise performance were evaluated by the above test methods, and the results are also shown in Table 4.

  As shown in Table 4, the tires of Examples 16 to 20 were able to reduce noise caused by the tread pattern while maintaining good drainage performance in comparison with the conventional example. In particular, good results were obtained when the shift amount d was 5% to 100% of the width L of the center main groove.

DESCRIPTION OF SYMBOLS 1 Tread part 1A Center part 1B Outer part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Belt layer 7 Belt cover layer 11, 12, 13 Main groove 20, 30, 40, 50 Land part 22, 52 Lug groove 31 , 41, 51 Narrow groove 32, 42 Inclined groove

Claims (8)

  In a pneumatic tire with a specified tire front and back mounting direction when the vehicle is mounted, three main grooves extending in the tire circumferential direction are provided in the tread portion, and the center position of the center main groove is shifted from the tire equator to the vehicle outer side. A narrow groove extending in the tire circumferential direction in each of two rows of center land portions located on the tire equator side of the tread portion A plurality of inclined grooves extending outward in the tire width direction from the narrow groove, the width of the center land portion on the vehicle outer side is larger than the width of the center land portion on the vehicle inner side, and on the shoulder side of the tread portion A pneumatic tire characterized in that a plurality of lug grooves extending in the tire width direction are provided in each of two rows of shoulder land portions positioned, and these lug grooves are not communicated with the main groove.   2. The pneumatic tire according to claim 1, wherein a ratio Wo / Wi of a width Wo of the center land portion outside the vehicle to a width Wi of the center land portion inside the vehicle is set in a range of 1.15 to 1.35. .   The pneumatic tire according to claim 1 or 2, wherein an intersection angle between the narrow groove and the inclined groove is in a range of 30 ° to 50 °.   The main groove outside the vehicle is narrower than the main groove inside the vehicle, and the ratio Li / Lo of the width Li of the main groove inside the vehicle to the width Lo of the main groove outside the vehicle is in the range of 1.05 to 1.25. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein an amount of deviation d between the center position of the center main groove and the tire equator is in the range of 5 to 100% of the width L of the center main groove. .   In the tread portion, the central portion including the center main groove and the outer portions located on both outer sides thereof are made of different rubber compositions, and the hardness of the central portion is higher than the hardness of the outer portion. The pneumatic tire according to any one of claims 1 to 5.   The pneumatic tire according to claim 6, wherein a width X of the center portion is in a range of 10% to 35% of a contact width TCW of the tread portion.   The pneumatic tire according to claim 7, wherein the difference between the hardness of the central portion and the hardness of the outer portion is in the range of 3-7.

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