JP6186250B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a block partitioned by grooves is formed on a tread surface.

  Generally, a pneumatic tire is manufactured by vulcanizing an unvulcanized tire in a mold. In such vulcanization molding, a release agent is applied to the surface of the unvulcanized tire in order to facilitate the release of the pneumatic tire from the mold after vulcanization. Therefore, there is a problem that the release agent is attached to the surface of the tire when it is new, the filler on the tread surface is difficult to be exposed, and the original performance of the pneumatic tire cannot be exhibited. As a means for improving the tire performance at the time of such a new article, there is a technique of providing a shallow groove shallower than the sipe on the tread surface of the land portion to increase the edge amount.

  For example, in Patent Document 1 below, thin ribs having a triangular cross section extending in the tire width direction are arranged in a saw blade shape in the tire circumferential direction on the tread surface of a land portion, and the tips of the thin ribs having a triangular cross section are arranged. A pneumatic tire directed toward the tire rotation direction is described. As a result, the traction on the snow road surface is enhanced by the scratching effect by the leading edge of the thin rib, and the traction property when new is improved.

  Further, in Patent Document 2 below, an inclined surface that inclines in the tire diameter inward direction from the center portion of the tread surface toward the end portion side is formed in the land portion, and the tread surface of the land portion including the inclined surface is A pneumatic tire having a plurality of shallow grooves formed therein is also described. In the pneumatic of Patent Document 2, the edge effect and the water absorption effect are exhibited by the shallow groove to improve the tire performance when new.

  However, the pneumatic tires of Patent Documents 1 and 2 were developed for the purpose of improving the running performance when new on a snow road surface, and are not considered for the running performance on a dry road surface with a high coefficient of friction. Driving performance on dry roads may be deteriorated.

Japanese Patent Laid-Open No. 2007-22242 JP 2006-151224 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire that achieves both running performance on a snow road surface and a dry road surface.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire of the present invention is a pneumatic tire in which a block divided by grooves on the tread surface is formed, and on the block surface, a plurality of fine ribs extending along the tire width direction are arranged in the tire circumferential direction. The thin ribs are formed so that the tread surface that appears in the cross section of the tire in the tire width direction passing through the thin ribs protrudes from both ends at the center in the tire width direction.

  In such a pneumatic tire, since a plurality of fine ribs extending along the tire width direction are arranged on the block surface, an edge effect at the time of a new article can be obtained, so that traveling performance on a snow road surface can be improved. Further, in the present invention, the thin rib is formed so that the tread surface of the block that appears in the cross section of the tire passing in the tire width direction protrudes from both ends at the center in the tire width direction. Usually, in a block at the time of rolling on a dry road surface, the contact pressure at both ends in the tire width direction tends to be higher than that at the center, and the contact pressure becomes uneven, so that the running performance is lowered. Since the tread surface protrudes from both ends at the center portion in the tire width direction as in the present invention, the contact pressure at the center portion in the tire width direction increases and the contact pressure of the block becomes uniform. The driving performance can be improved. As a result, according to the pneumatic tire of the present invention, it is possible to achieve both running performance on a snow road surface and a dry road surface. The tread according to the present invention is configured by the rib surface of the thin rib when the thin rib is formed over the entire width of the block in the tire width direction, and the thin rib is partly in the tire width direction of the block. In the case where only the first rib is formed, the rib surface of the fine rib and the block surface are included.

  In the pneumatic tire of the present invention, it is preferable that the rib height from the block surface of the thin rib increases from both end portions in the tire width direction toward the center portion. Moreover, the pneumatic tire of this invention WHEREIN: It is preferable that the said thin rib is arranged only in the center part of the tire width direction among the said block surfaces. According to such a configuration, the running performance on the snow road surface can be improved by the edge effect of the thin ribs, and the tread surface protrudes from both ends at the center in the tire width direction, so that the ground contact pressure of the block is made uniform and dry. Driving performance on the road can be improved.

  In the pneumatic tire of the present invention, it is preferable that the plurality of thin ribs are arranged so that the height of each rib from the block surface increases in order from one side to the other side in the tire circumferential direction. For example, in the block at the time of braking, the ground contact pressure on the kicking side, which is the rear in the tire rotation direction, is higher than the ground pressure on the stepping side, which is the front in the tire rotation direction, but the rib height of each fine rib is kicked. By setting it to increase in order from the exit side to the stepping side, the ground pressure is equalized in the tire circumferential direction during braking, so the edge effect by the thin ribs is improved while improving the driving performance on the dry road surface. The driving performance on snowy roads can be improved. On the other hand, in the block at the time of driving, the contact pressure on the stepping side that is the front in the tire rotation direction is higher than the contact pressure on the kicking side that is the rear in the tire rotation direction. By setting to increase in order from the side toward the kicking side, the contact pressure is made uniform in the tire circumferential direction during driving, so the edge effect by the thin ribs is improved while improving the running performance on dry road surface The driving performance on snowy roads can be improved.

  In the pneumatic tire of the present invention, it is preferable that the rib width in the tire circumferential direction of the thin ribs gradually increases from both end portions in the tire width direction toward the center portion. According to such a configuration, since the contact pressure at the center in the tire width direction is further increased and the contact pressure of the block is further uniformized, the running performance on the dry road surface can be effectively improved.

The expanded view which shows an example of the tread surface of the pneumatic tire which concerns on this invention The perspective view which expands and shows a block AA sectional view of the block of FIG. BB sectional view of the block of FIG. Distribution diagram of ground contact pressure of block according to the first embodiment The perspective view of the block concerning a 2nd embodiment. Distribution diagram of ground contact pressure of block according to second embodiment The perspective view of the block concerning a 2nd embodiment. Distribution diagram of ground contact pressure of block according to second embodiment The perspective view of the block concerning a 3rd embodiment. The perspective view of the block which concerns on 4th Embodiment The top view of the block concerning a 5th embodiment The perspective view of the block concerning other embodiments The perspective view of the block concerning other embodiments The perspective view of the block concerning the comparative example 1 Distribution diagram of contact pressure of block according to Comparative Example 1

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a development view showing an example of a tread surface of a pneumatic tire according to the present invention. The pneumatic tire includes a tread pattern having a plurality of blocks 1. The block 1 is divided by a main groove 2 extending in the tire circumferential direction CD and a lateral groove 3 extending in the tire width direction WD, and five rows of blocks 1 are arranged symmetrically with respect to the tire equator line CL.

[First Embodiment]
FIG. 2 is an enlarged perspective view showing the block 1. A plurality of thin ribs 10 extending along the tire width direction WD are arranged on the surface 1a of the block 1 in the tire circumferential direction CD. The thin ribs 10 are protrusions that protrude from the block surface 1a and extend along the tire width direction WD. In the present embodiment, the plurality of thin ribs 10 all have the same shape. By arranging a plurality of thin ribs 10 extending along the tire width direction WD on the block surface 1a, an edge effect when new can be obtained. The cross section obtained by cutting the thin rib 10 in the tire circumferential direction CD has a quadrangular shape. Here, the quadrangle includes a rectangle, a square, a trapezoid, and the like, and has a shape in which the upper end of the thin rib 10 can come into surface contact with the road surface.

  3A is a cross-sectional view taken along the line AA of the block 1 in FIG. 2, and FIG. 3B is a cross-sectional view taken along the line BB of the block 1 in FIG. Here, the AA cross section is a cross section in the tire width direction passing through the thin rib 10. On the other hand, the BB cross section is a cross section in the tire width direction that does not pass through the thin rib 10. As shown in FIG. 3A, the thin rib 10 is formed so that the tread surface 11 appearing in the tire width direction cross section (AA cross section) passing through the thin rib 10 protrudes from both ends at the center in the tire width direction WD. Yes. In the present embodiment, since the thin rib 10 is formed over the entire width of the block 1 in the tire width direction WD, the tread surface 11 is constituted only by the rib surface 10 a of the thin rib 10.

  In the present embodiment, in the thin rib 10, each rib height h from the block surface 1a increases from both ends in the tire width direction WD toward the center. Thereby, the tread surface 11 comprised by the rib surface 10a protrudes rather than both ends in the center part of the tire width direction WD. Since the tread surface 11 protrudes from both ends at the center portion in the tire width direction WD, the contact pressure at the center portion in the tire width direction WD increases and the contact pressure of the block 1 becomes uniform. Driving performance can be improved (details will be described later).

  On the other hand, FIG. 14 shows a block 1 in which the tread surface 11 has the same height at the center and both ends in the tire width direction WD. At this time, the distribution of the ground pressure of the block 1 during rolling, braking and driving on the dry road surface is as shown in FIG. FIG. 15 shows the distribution of the contact pressure when the block 1 of FIG. 14 is viewed from above. The contact pressure in the region indicated as “high” is higher than the contact pressure in the region indicated as “low”. It is shown that. In the rolling block 1, as shown in FIG. 15A, the ground pressure at the outer edge of the block 1 is higher than the ground pressure at the center. Thus, in the block at the time of rolling on the dry road surface, the contact pressure at both end portions in the tire width direction WD is likely to be higher than that in the central portion. Further, in the block 1 at the time of braking, as shown in FIG. 15B, the ground pressure on the kicking side 1c that is the rear in the tire rotation direction R is the ground pressure on the stepping side 1b that is the front in the tire rotation direction R. Higher than. On the other hand, in the block 1 at the time of driving, as shown in FIG. 15C, the contact pressure on the stepping side 1b that is the front in the tire rotation direction R is the contact pressure on the kicking side 1c that is the rear in the tire rotation direction R. Higher than.

  On the surface 1a of the block 1 of the present invention, as described above, a plurality of thin ribs 10 extending along the tire width direction WD are arranged in the tire circumferential direction CD, and in a tire width direction cross section passing through the thin ribs 10. The thin rib 10 is formed so that the appearing tread 11 protrudes from both ends at the center in the tire width direction WD. The effect of the pneumatic tire of the present invention will be described in detail with reference to FIG.

  4A shows the distribution of the ground pressure of the block 1 during rolling, FIG. 4B shows the distribution of the ground pressure of the block 1 during braking, and FIG. 4C shows the distribution of the ground pressure of the block 1 during driving. Distribution is shown. At the time of rolling, by projecting the tread 11 from the both ends at the center in the tire width direction WD, the contact pressure at the center in the tire width direction WD increases and the contact pressure of the entire block 1 becomes uniform. Therefore, the running performance on the dry road surface can be improved. At the time of braking and driving, even if the contact pressure at the center in the tire width direction WD increases, the distribution of the contact pressure of the entire block 1 is almost the same as in FIGS. 15 (b) and 15 (c). no change. This is because, as shown in FIGS. 15 (b) and 15 (c), even when the tread surface 11 is flat, the contact pressure at the center portion in the tire width direction WD is higher than both ends.

  The rib height h of the thin rib 10 is preferably 0.15 to 1 mm. When the rib height h is lower than 0.15 mm, a sufficient edge effect cannot be obtained. When the rib height h is higher than 1 mm, the rib effect is insufficient and the edge effect is lowered due to falling. Moreover, it is preferable that the rib width w in the tire circumferential direction CD of the thin rib 10 is 0.3 to 3.0 mm. When the rib width w is narrower than 0.3 mm, the width is small with respect to the rib height h, and a fall occurs as described above, and the edge effect is lowered. When the rib width w is wider than 3.0 mm, it is difficult to provide a sufficient number of edges on the block. Moreover, it is preferable that the space | interval p of the adjacent thin rib 10 is 0.2-3.0 mm, and it is preferable that it is 60-110% of the rib width w. When the interval p is narrower than 0.2 mm, the close contact between the thin ribs becomes remarkable, and the edge effect cannot be obtained. When the interval p is wider than 3.0 mm, it is difficult to provide a sufficient number of edges as with the rib width w. When a sipe (not shown) is formed on the block surface 1a, the groove depth of the sipe is 2 to 7 mm, for example, and is about 50% of the depth of the main groove 2.

  In the present embodiment, as shown in FIG. 2, eight thin ribs 10 are provided on the block surface 1a. However, the number of the thin ribs 10 is not particularly limited, and the above rib width w and interval p are taken into consideration. It can be set as appropriate.

  The pneumatic tire of the present invention is the same as a normal pneumatic tire except that the fine ribs as described above are formed on the block surface, and any conventionally known material, shape, structure, etc. can be adopted in the present invention. .

[Second Embodiment]
In the pneumatic tire of the present invention, the plurality of thin ribs 10 may be arranged such that each rib height h from the block surface 1a increases in order from one side to the other side in the tire circumferential direction CD. preferable.

  For example, in the pneumatic tire in which the block 1 is formed, when the tire rotation direction R is the direction shown in FIG. 5, that is, as shown in FIG. The case where it is set so as to increase in order toward the stepping side 1b from will be described.

  FIG. 6A shows the distribution of the ground pressure of the block 1 during rolling, and FIG. 6B shows the distribution of the ground pressure of the block 1 during braking. When the tire rotation direction R is the direction shown in FIG. 5, the contact pressure on the stepping side 1b is higher than that on the kicking side 1c, and the contact pressure is equalized in the tire circumferential direction CD during braking as shown in FIG. 6 (b). Therefore, while improving the running performance on the dry road surface, the edge effect by the thin ribs 10 can be enhanced particularly during braking to improve the running performance on the snow road surface. 6A, the contact pressure on the stepping side 1b is higher than the contact pressure on the kick-out side 1c, but the influence is small because the applied horizontal force is small. (There is no problem because the friction coefficient required for rolling is small.)

  Next, in the pneumatic tire in which the block 1 is formed, when the tire rotation direction R is the direction shown in FIG. 7, that is, as shown in FIG. 7, each rib height h of the thin rib 10 is set from the depression side 1b. The case where it sets so that it may become high in order toward the kicking-out side 1c is demonstrated.

FIG. 8A shows the distribution of the ground pressure of the block 1 during rolling, and FIG. 8B shows the distribution of the ground pressure of the block 1 during driving. When the tire rotation direction R is the direction shown in FIG. 7, the ground pressure on the kicking side 1c is higher than that on the stepping side 1b, and the ground pressure is equalized in the tire circumferential direction CD during driving as shown in FIG. 8 (b). Therefore, while improving the running performance on the dry road surface, it is possible to improve the running performance on the snow road surface by enhancing the edge effect particularly during driving by the thin rib 10. 8A, the ground pressure on the kicking side 1c is higher than the ground pressure on the stepping side 1b, but the influence is small because the applied horizontal force is small. (There is no problem because the friction coefficient required for rolling is small.)
[Third Embodiment]
In the pneumatic tire of the present invention, as shown in FIG. 9, it is preferable that the thin ribs 10 are arranged only in the center portion of the block surface 1a in the tire width direction WD. In this example, the rib height h of the thin ribs 10 is constant in the tire width direction WD, and the rib heights h of the plurality of thin ribs 10 arranged in the tire circumferential direction CD are all equal. In this embodiment, the tread surface 11 that appears in the cross section of the tire width direction passing through the thin rib 10 is constituted by the rib surface 10a of the thin rib 10 and the block surface 1a. Thereby, the tread surface 11 comprised by the rib surface 10a and the block surface 1a protrudes rather than both ends in the center part of the tire width direction WD. The distribution of the contact pressure at this time is substantially the same as that of the block according to the first embodiment, and it is possible to achieve both running performance on a snow road surface and a dry road surface.

[Fourth Embodiment]
In the block according to the third embodiment, as shown in FIG. 10, the plurality of thin ribs 10 each have a rib height h from the block surface 1 a from one side CD1 to the other side CD2 in the tire circumferential direction CD. It is more preferable that they are arranged so as to increase in order. The distribution of the contact pressure at this time is substantially the same as that of the block according to the second embodiment, and it is possible to achieve both running performance on a snow road surface and a dry road surface.

[Fifth Embodiment]
In the pneumatic tire of the present invention, it is preferable that the rib width w of the thin rib 10 in the tire circumferential direction CD is gradually increased from both end portions in the tire width direction WD toward the center portion. FIG. 11 is a plan view of the block 1 according to this embodiment. As described above, by gradually increasing the rib width w from both end portions in the tire width direction WD toward the center portion, the contact pressure at the center portion in the tire width direction WD is further increased and the contact pressure of the block 1 is further uniformized. Therefore, the running performance on the dry road surface can be effectively improved.

[Other Embodiments]
(1) The tread pattern of the pneumatic tire of the present invention is not particularly limited as long as it has a block, and ribs may be mixed. The shape of the block in which the thin ribs are formed is not limited to a substantially square shape as shown in the above-described embodiment, and other shapes such as a rectangle, a parallelogram, and a hexagon can be employed.

  (2) In the first embodiment, the thin rib 10 has the rib height h from the block surface 1a that gradually increases from both ends in the tire width direction WD toward the central portion. As shown in FIG. 12, each rib height h may increase stepwise from both ends in the tire width direction WD toward the center.

  (3) In said 1st Embodiment, although the thin rib 10 is formed covering the full width of the tire width direction WD of the block 1, as shown in FIG. You may form only in the center part of WD.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, each performance evaluation of the tire was performed as follows.

(1) Snow braking performance The tire was mounted on a real vehicle (3000 cc class FR sedan) to run on the snow road surface, and the inverse of the braking distance when the braking force was applied at a speed of 40 km / h and the ABS was operated was evaluated. . The result of Comparative Example 1 is shown as an index with a value of 100, and the larger the value, the better the braking performance on the snow road surface.

(2) Snow acceleration performance The tire was mounted on the same actual vehicle as described above, and the acceleration time from 0 km / h (stopped) to 40 km / h on the snow road surface was measured. The reciprocal of the actually measured value of Comparative Example 1 is shown as an index, and the larger the value, the better the acceleration performance (drive performance) on the snow road surface.

(3) Dry performance A tire is mounted on the same actual vehicle as above, and a dry asphalt road test course is run, and two drivers perform a linear stability, lane change, cornering, braking performance feeling test. Carried out. The result of Comparative Example 1 is shown as an index with the value 100, and the larger the value, the better the running performance on the dry road surface.

  In a pneumatic tire having a tread pattern as shown in FIG. 1 (tire size: 205 / 65R15), the treads appearing in the cross section of the tire in the tire width direction passing through the thin ribs as shown in FIG. The thin ribs formed so as to have the same height at the part are referred to as Comparative Example 1, and the thin ribs shown in FIGS. 2, 5, 9, and 10 are formed in Example 1, Example 2, and Example 2, respectively. As Example 3 and Example 4, snow braking performance, snow acceleration performance, and dry performance were evaluated. The snow acceleration performance of Examples 2 and 4 was evaluated by setting the tire rotation direction opposite to the direction shown in FIGS. The evaluation results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 4, snow braking performance, snow acceleration performance, and dry performance were improved as compared with Comparative Example 1, and both running performance on a snow road surface and a dry road surface could be achieved.

1 block 1a block surface 1b stepping side 1c kicking side 2 main groove 3 transverse groove 10 thin rib 10a rib surface 11 tread surface h rib height w rib width WD tire width direction CD tire circumferential direction R tire rotation direction

Claims (4)

In a pneumatic tire in which blocks divided by grooves on the tread surface are formed,
On the block surface, a plurality of thin ribs extending in the tire width direction are arranged in the tire circumferential direction,
The thin rib is formed so that the tread surface that appears in the cross section of the tire width direction passing through the thin rib protrudes from both ends at the center in the tire width direction,
The narrow ribs are air-filled tire you characterized in that it is arranged only in the central portion in the tire width direction of the block surfaces. In a pneumatic tire in which blocks divided by grooves on the tread surface are formed,
On the block surface, a plurality of thin ribs extending in the tire width direction are arranged in the tire circumferential direction,
The thin rib is formed so that the tread surface that appears in the cross section of the tire width direction passing through the thin rib protrudes from both ends at the center in the tire width direction,
It said plurality of narrow ribs, air-filled tires each rib height from the block surface you characterized in that it is arranged to be higher in order toward the one side in the tire circumferential direction to the other side. In a pneumatic tire in which blocks divided by grooves on the tread surface are formed,
On the block surface, a plurality of thin ribs extending in the tire width direction are arranged in the tire circumferential direction,
The thin rib is formed so that the tread surface that appears in the cross section of the tire width direction passing through the thin rib protrudes from both ends at the center in the tire width direction,
Rib width in the tire circumferential direction of the narrow rib is air-filled tire you characterized in that gradually increases toward the central portion from both ends in the tire width direction. The pneumatic tire according to any one of claims 1 to 3 , wherein a rib height of the fine ribs from the block surface increases from both end portions in the tire width direction toward a central portion.

Images