JP2006035974A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving the road noise, controllability and stability, and the anti-abrasiveness without risk of impairing any of them. <P>SOLUTION: The cap tread rubber layer 11 of this tire is composed of a first division rubber layer part 15 positioned in the division between a tire equator surface 12 and the first boundary line 13 on the inside of a vehicle, a second division rubber layer part 16 positioned in the division between the tire equator surface 12 and the second boundary line 14 on the outside of the vehicle, a third division rubber layer part 17 positioned in a division inside the vehicle more than the first boundary line 13, and a fourth division rubber layer part 18 positioned in a division outside the vehicle more than the second boundary line 14. The rubber hardness of the rubber layer parts 15, 16, 17, 18 should meet the relation that the first division rubber layer part < the second division rubber layer part < the third division rubber layer part ≤ the fourth division rubber layer part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that improves road noise, steering stability, and wear resistance.

  Conventionally, as a technique for improving road noise of pneumatic tires, there is known a method of reducing road noise by reducing the hardness of the tread rubber, thereby mitigating the impact from the road surface due to the contact of the tread surface. . However, when the hardness of the tread rubber is lowered, the rigidity of the blocks and ribs formed on the tread surface is lowered, so that the steering stability is inevitably deteriorated.

  Therefore, in recent years, there has been proposed a pneumatic tire in which the center region of the cap tread rubber layer is made of rubber having a lower hardness than the conventional one and both shoulder regions are made of rubber having a higher hardness (see, for example, Patent Document 1). . In the center area of the tread, the impact from the road surface is absorbed by rubber with low hardness to reduce road noise, while the lowering of the grip in the center area is compensated in the shoulder area, and the same steering stability as before is achieved. I try to secure it.

However, the demand from the market does not stop, and further improvements are required from the aspects of safety and environment.
JP 2001-10308 A

  An object of the present invention is to provide a pneumatic tire that can improve road noise, steering stability, and wear resistance without any loss.

  In the pneumatic tire having a cap tread rubber layer in the tread portion and designating a vehicle mounting direction, the present invention that achieves the above object is arranged so that the cap tread rubber layer is located on the vehicle inner side from the tire equator surface and the tire equator surface. A second zone located in a zone between a first zone rubber layer portion located in a zone between the first boundary line and a tire equator plane and a second border line located outside the vehicle from the tire equator plane. An area rubber layer portion, a third area rubber layer portion located in an area inside the vehicle from the first boundary line, and a fourth area rubber layer portion located in an area outside the vehicle from the second boundary line. The rubber hardness of each zone rubber layer portion satisfies the relationship of the first zone rubber layer portion <second zone rubber layer portion <third zone rubber layer portion ≦ fourth zone rubber layer portion. .

  According to the present invention described above, by using a rubber having a low rubber hardness for the rubber layer portion located on the center side of the tread portion, while absorbing the impact from the road surface, at least three types of rubbers having different hardnesses, that is, By disposing at least three types of rubber layer portions with different spring constants, vibration frequency is dispersed, and further, rigidity is increased on the shoulder side of the tread portion, thereby suppressing vibration transmitted to the sidewall portion. Therefore, road noise can be effectively improved.

  Further, since the rigidity on the shoulder side of the tread portion is increased, the decrease in grip force on the center side is compensated on the shoulder side, and the rubber hardness of the second zone rubber layer portion located on the vehicle outer side on the center side is further increased on the vehicle inner side. During cornering where the tread surface on the outside of the vehicle has a greater influence than the rubber hardness of the second zone rubber layer, which is lower than that of the first zone rubber layer on the inside of the vehicle. The grip power of can be increased. Therefore, it is possible to improve the steering stability.

  Furthermore, since the rigidity on the shoulder side of the tread portion is increased, it is possible to suppress the wear on the shoulder side where the progress of wear is usually faster than the center side, so that the wear resistance can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the pneumatic tire of the present invention, where 1 is a tread portion and 2 is a sidewall portion. The pneumatic tire has a vehicle mounting direction designated, and when the vehicle is mounted, the A side is the vehicle inner side and the B side is the vehicle outer side.

  The carcass layer 3 is mounted between the right and left bead portions (not shown) on the tire inner side, and both end portions thereof are folded back from the tire inner side to the outer side around bead cores (not shown) arranged in the bead portions. A plurality of belt layers 5 are arranged on the outer peripheral side of the carcass layer 3 of the tread portion 1, and a tread rubber layer 6 is provided on the outer peripheral side of the belt layer 5. A plurality of circumferential grooves 8 extending in the tire circumferential direction are formed on the tread surface 7 of the tread rubber layer 6, and land portions 9 are formed in sections between the circumferential grooves 8.

  The tread rubber layer 6 includes an under tread rubber layer 10 adjacent to the belt layer 5 and a cap tread rubber layer 11 disposed on the outer peripheral side thereof. The under-tread rubber layer 10 is integrally formed from one type of rubber as in the conventional case.

  The cap tread rubber layer 11 is divided into four sections by a tire equatorial plane 12, a first boundary line 13 located on the vehicle inner side from the tire equatorial plane 12, and a second boundary line 14 located on the outer side of the tire from the tire equatorial plane 12. The first zone rubber layer 15 located in the zone between the tire equator plane 12 and the first boundary line 13 and the second zone rubber located in the zone between the tire equator plane 12 and the second boundary line 14 It is composed of a layer part 16, a third area rubber layer part 17 located in an area inside the vehicle from the first boundary line 13, and a fourth area rubber layer part 18 located in an area outside the vehicle from the second boundary line 15. It is.

  The rubber hardness of each zone rubber layer portion 15, 16, 17, 18 satisfies the relationship of the first zone rubber layer portion <second zone rubber layer portion <third zone rubber layer portion ≦ fourth zone rubber layer portion. It has become.

  In this way, the cap tread rubber layer 11 is divided into four parts, and rubber having low rubber hardness is used for the first and second section rubber layer parts 15 and 16 located on the center side of the tread part 1, so that the road surface at the time of ground contact is obtained. By disposing at least three kinds of rubber layers 15, 16, and 17 having different spring constants, the vibration frequency is dispersed and further on the shoulder side. Since the rigidity of the land portion 9 is increased, vibration can be suppressed. Therefore, it is possible to effectively reduce road noise.

  On the other hand, since the rigidity of the land portion 9 is high on the shoulder side, the decrease in grip force on the center side due to the use of rubber having low hardness is compensated on the shoulder side, and further, the second zone rubber layer portion located outside the vehicle on the center side 16 so that the rubber hardness of the second zone rubber layer portion 16 is the same as that of the first zone rubber layer portion 15 inside the vehicle, so that the rubber hardness of the zone 16 is higher than that of the first zone rubber layer portion 15 inside the vehicle. Grip strength during cornering, where the outer tread surface is greatly affected, can be increased. Therefore, the steering stability can be improved.

  In addition, since the rigidity of the land portion 9 on the shoulder side is increased, it is possible to suppress wear on the shoulder side, where the wear progresses faster than the center side, so that the wear resistance can be improved.

  If the rubber hardness is such that the first zone rubber layer portion> the second zone rubber layer portion, the steering stability cannot be improved. Further, when the above relationship is reversed, that is, when the first zone rubber layer portion> the second zone rubber layer portion> the third zone rubber layer portion ≧ the fourth zone rubber layer portion, road noise and wear resistance are deteriorated.

  In the present invention, as the positions of the first boundary line 13 and the second boundary line 14, if the length in the tire axial direction from the tire equator surface 12 to the ground contact edge E of the tread surface 7 on both sides is L (mm), Each can be in the range of 0.1 L to 0.8 L from the tire equatorial plane 12.

  When the positions of the first boundary line 13 and the second boundary line 14 are located closer to the tire equatorial plane 12 than 0.1 L from the tire equatorial plane 12, the areas of the first zone rubber layer portion 15 and the second zone rubber layer portion 16 are set. Becomes too narrow, making it difficult to improve road noise. On the other hand, if it is located on the grounding end E side from 0.8 L, the steering stability and the wear resistance cannot be improved. Preferably, it is 20-70, More preferably, 30-60 is good. The ground contact E mentioned here is a pneumatic tire mounted on a standard rim specified in JATMA (2003), filled with air pressure corresponding to the maximum load capacity, and loaded with 88% of the maximum load capacity. This is the ground end of the tread surface 7 when added.

  The JIS A hardness of the rubber of the first zone rubber layer 15 is 46 to 68, the JIS A hardness of the rubber of the second zone rubber layer 16 is 48 to 70, and the JIS A of the rubber of the third zone rubber layer 17 is. The above relationship is preferably satisfied when the hardness is 50 to 72 and the JIS A hardness of the rubber of the fourth zone rubber layer portion 18 is 50 to 74.

  Incidentally, in a pneumatic tire for winter, the JIS A hardness of the rubber in the first zone rubber layer 15 is 46 to 58, the JIS A hardness of the rubber in the second zone rubber layer 16 is 48 to 60, and the third zone rubber. The rubber of the layer 17 has a JIS A hardness of 50 to 62 and the rubber of the fourth zone rubber layer 18 has a JIS A hardness of 50 to 64. The JIS A hardness of the rubber of the section 15 is 54 to 68, the JIS A hardness of the rubber of the second section rubber layer section 16 is 56 to 70, the JIS A hardness of the rubber of the third section rubber layer section 17 is 58 to 72, A range where the JIS A hardness of the rubber of the four-zone rubber layer portion 18 is 58 to 74 is used.

  When the JIS A hardness of the rubber of the first zone rubber layer portion 15 is lower than 46, and when the JIS A hardness of the rubber of the second zone rubber layer portion 16 is lower than 48, steering stability is improved in a winter pneumatic tire. Incurs a decline. Conversely, if the JIS A hardness of the rubber in the first zone rubber layer portion 15 is higher than 68, and if the JIS A hardness of the rubber in the second zone rubber layer portion 16 is higher than 70, road noise in a pneumatic tire for summer use. Gets worse.

  When the JIS A hardness of the rubber of the third zone rubber layer portion 17 and the fourth zone rubber layer portion 18 is lower than 50, the wear resistance and the handling stability are lowered in a winter pneumatic tire. On the contrary, when the JIS A hardness of the rubber of the third zone rubber layer portion 17 is higher than 72, and when the JIS A hardness of the rubber of the fourth zone rubber layer portion 18 is higher than 74, road noise occurs in a summer pneumatic tire. Invite the deterioration.

  Preferably, the rubber hardness of the third zone rubber layer portion 17 and the fourth zone rubber layer portion 18 is such that the relationship of the third zone rubber layer portion <the fourth zone rubber layer portion satisfies the relation of steering stability. It is good for further enhancement.

  In the above embodiment, the boundary line between the first zone rubber layer portion 15 and the second zone rubber layer portion 16 is located on the tire equator plane 12, but in the present invention, it is within 5 mm from the tire equator plane 12 to both sides in the tire axial direction. In which the boundary position between the first zone rubber layer portion 15 and the second zone rubber layer portion 16 is substantially regarded as the first and second zone rubber layer portions 15 and 16, and the first zone of the present invention. The zone rubber layer portion 15 and the second zone rubber layer portion 16 are included.

  Moreover, in the said embodiment, although the tread rubber layer 6 showed the example which consists of the under tread rubber layer 10 and the cap tread rubber layer 11, the tread rubber layer 6 was formed only from the cap tread layer 11 without the under tread rubber layer 10. It may be what you did. Further, a wing tip rubber layer may be disposed on both sides of the cap tread rubber layer 11.

  Although this invention can be preferably used especially for the pneumatic tire for passenger cars, it is not limited to it.

  The tire size is the same for 205 / 55R16, and the cap tread rubber in the tires 1 to 5 and comparative tires 1 and 2 and tire 1 of the present invention having the structure shown in FIG. A conventional tire 1 having a layer composed of one type of rubber, and a conventional tire 2 having a cap tread rubber layer divided into a center region and two shoulder regions in the tire 1 of the present invention were formed.

  Each of these test tires is mounted on a rim having a rim size of 16 × 6 1/2 JJ, the air pressure is set to 220 kPa, and the vehicle is mounted on a vehicle with a displacement of 2000 cc. By the following test methods, steering stability, road noise, and abrasion resistance are used. As a result of the evaluation test, the results shown in Table 1 were obtained.

Steering stability In the dry road test course, a feeling test by a test driver was performed, and the result was shown as an index value with the conventional tire 1 as 100. The larger this value, the better the steering stability.

Road noise In the dry road test course, the in-vehicle noise when traveling straight at a speed of 60 km / h was measured. The larger this value, the lower the road noise and the better the noise performance.

Abrasion resistance After traveling 12,000 km on a general roadway, the amount of wear was measured, and the result was shown as an index value with the conventional tire 1 as 100. The higher this value, the better the wear resistance.

  From Table 1, it can be seen that the tire of the present invention can be improved without impairing all of road noise, steering stability and wear resistance.

It is a tire meridian principal part sectional view showing one embodiment of the pneumatic tire of the present invention.

Explanation of symbols

1 Tread
2 Side wall 3 Carcass layer
6 tread rubber layer 11 cap tread rubber layer 12 tire equatorial plane 13 first boundary line 14 second boundary line 15 first zone rubber layer portion 16 second zone rubber layer portion 17 third zone rubber layer portion 18 fourth zone rubber layer Part

Claims (4)

  In a pneumatic tire having a cap tread rubber layer in a tread portion and specifying a vehicle mounting direction, the cap tread rubber layer is disposed between the tire equator plane and a first boundary line located on the vehicle inner side from the tire equator plane. A first zone rubber layer portion located in the zone of the tire, a second zone rubber layer portion located in a zone between the tire equator plane and a second boundary line located on the vehicle outer side from the tire equator plane, and the first It comprises a third zone rubber layer portion located in a zone inside the vehicle from the boundary line and a fourth zone rubber layer portion located in a zone outside the vehicle from the second border line, and the rubber hardness of each zone rubber layer portion Is a pneumatic tire in which the relationship of the first zone rubber layer portion <the second zone rubber layer portion <the third zone rubber layer portion ≦ the fourth zone rubber layer portion is satisfied.   2. The pneumatic tire according to claim 1, wherein rubber hardnesses of the third zone rubber layer portion and the fourth zone rubber layer portion satisfy a relationship of third zone rubber layer portion <fourth zone rubber layer portion.   When the length in the tire axial direction from the tire equatorial plane to the contact edge of the tread surface on each side is L (mm), the first boundary line and the second boundary line are 0.1 L to 0 from the tire equatorial plane, respectively. The pneumatic tire according to claim 1 or 2, which is located in a range of .8L.   The JIS A hardness of the rubber of the first zone rubber layer portion is 46 to 68, the JIS A hardness of the rubber of the second zone rubber layer portion is 48 to 70, and the JIS A hardness of the rubber of the third zone rubber layer portion is The pneumatic tire according to claim 1, 2, or 3, wherein the JIS A hardness of the rubber of the fourth zone rubber layer portion is 50 to 74.

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