JP6557996B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that is suitable as a racing tire, and more particularly to a pneumatic tire that can instantaneously and accurately determine the degree of wear of a tread portion.

  2. Description of the Related Art Conventionally, in a pneumatic tire, in order to determine the degree of wear of a tread portion, a wear degree display means is provided on the tread portion. As such wear level display means, it has been proposed to provide a wear level display hole in the tread portion and grasp the wear state based on the remaining depth of the wear level display hole (see, for example, Patent Document 1). .

  However, it is difficult to instantly determine the degree of wear of the tread portion with a simple wear degree display hole. In particular, in an automobile race, it is necessary to immediately determine whether or not to replace a tire after judging the degree of wear instantaneously. In order to accurately determine the degree, it is necessary to measure the remaining depth of the wear degree display hole, and it is difficult to instantaneously determine the degree of wear.

  As another means for indicating the degree of wear, a rubber column consisting of multiple layers of rubber layers with different colors along the depth direction is embedded in the tread so that different colored rubber layers appear as wear progresses. (See, for example, Patent Document 2). However, in this case, although it is possible to grasp a rough wear state, it is difficult to accurately determine the degree of wear. Moreover, since the colored rubber layer exhibits different behavior with respect to the surrounding rubber, this also causes uneven wear.

  Further, as another wear degree display means, there is one in which a plurality of wear degree display holes having different depths are provided in the tread portion so that the shallow wear degree display holes disappear as the wear progresses (for example, patents). Reference 3). However, in this case as well, although it is possible to grasp a rough wear state, it is difficult to accurately determine the degree of wear. Further, when the number of wear degree display holes is increased in order to more accurately determine the degree of wear, there is a possibility that the running performance of the pneumatic tire is adversely affected due to the reduction of the contact area.

JP 2000-255221 A Japanese Patent Laid-Open No. 10-76814 JP 2006-232152 A

  An object of the present invention is to provide a pneumatic tire that can instantaneously and accurately determine the degree of wear of a tread portion.

The pneumatic tire of the present invention for achieving the above object is provided with a pair of wear degree display grooves extending in parallel to the tread portion, and one of the wear degree display grooves is formed to have a constant depth, The other wear degree display groove is formed so that the depth gradually changes along the longitudinal direction, and the pair of wear degree display grooves have a shape when the tread surface of the tread portion is viewed from directly above. It has a wave shape .

  In the present invention, a pair of wear degree display grooves extending in parallel with the tread portion are provided, one of the wear degree display grooves is formed so as to have a constant depth, and the other wear degree display groove has a longitudinal depth. As the wear progresses, the length of the other wear degree display groove changes, and the other wear degree is obtained using the length of one wear degree display groove as an index. The degree of wear of the tread portion can be determined instantaneously and accurately based on the change in the length of the display groove. Therefore, in an automobile race, it is possible to determine the necessity of tire replacement smoothly by determining the degree of wear instantaneously. Further, since the pair of wear degree display grooves described above do not require a large depression or a large number of depressions, the influence on various performances of the pneumatic tire can be minimized.

  In the present invention, it is preferable that the pair of wear degree display grooves have the same shape and the same length when the tread surface is viewed from directly above. Moreover, it is preferable that the mutual space | interval G of a pair of abrasion degree display groove | channel exists in the range of 2 mm <= G <= 10mm. This facilitates the comparison between one wear degree display groove and the other wear degree display groove, so that the change in the length of the other wear degree display groove can be grasped more accurately.

  In the present invention, the pair of wear degree display grooves are preferably disposed at a plurality of locations in the tire circumferential direction, particularly at least 6 locations in the tire circumferential direction. Thereby, the wear degree display groove can be easily found. Therefore, even in a vehicle such as a racing car that is covered with a cowl and in which a tire is difficult to see, the wear degree display groove can be easily confirmed.

  Moreover, it is preferable that a pair of abrasion degree display groove | channels are arrange | positioned in the multiple places of a tire width direction, especially at least 3 places of a tire width direction. In this case, in a vehicle with a camber angle or a vehicle in which a pneumatic tire is set to a low internal pressure, uneven wear such as center wear and shoulder wear can be determined instantaneously and accurately.

  In the present invention, the depth of the other wear degree display groove is such that the ratio of the wear amount to the maximum depth of the other wear degree display groove and the ratio of the disappearance amount to the total length of the other wear degree display groove have a proportional relationship. Is preferably changed along its longitudinal direction. By associating the ratio of the wear amount with respect to the maximum depth of the other wear degree display groove and the ratio of the disappearance amount with respect to the total length of the other wear degree display groove, the degree of wear can be easily determined.

  The thickness W of each of the pair of wear degree display grooves is preferably in the range of 0.5 mm ≦ W ≦ 2.0 mm. Thereby, the influence on various performances of the pneumatic tire can be minimized while ensuring the visibility of the wear degree display groove.

1 is a perspective view showing a pneumatic tire according to an embodiment of the present invention. It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is a perspective view which shows a pair of abrasion degree display groove | channel. It is a top view which shows a pair of abrasion degree display groove | channel. It is a top view which shows the residual state of a pair of abrasion degree display groove | channel when abrasion of a tread part advances. It is a top view which shows the modification of a pair of wear degree display groove | channel. It is a top view which shows the other modification of a pair of wear degree display groove | channel. It is sectional drawing which shows the state which notched the other abrasion degree display groove | channel along the longitudinal direction.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a pneumatic tire according to an embodiment of the present invention, and FIGS. 3 to 5 show a pair of wear degree display grooves formed in the pneumatic tire. The pneumatic tire of this embodiment is a slick tire for racing.

  As shown in FIGS. 1 and 2, the pneumatic tire of the present embodiment includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions that are disposed on both sides of the tread portion 1. 2 and 2 and a pair of bead portions 3 and 3 disposed on the inner side in the tire radial direction of the sidewall portions 2.

  A two-layer carcass layer 4 is mounted between the pair of bead portions 3 and 3. These carcass layers 4 include a plurality of reinforcing cords extending in the tire radial direction, and are folded back from the tire inner side to the outer side around bead cores 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  As shown in FIG. 1, a pair of wear degree display grooves 11 and 12 are formed in the tread portion 1 at a plurality of locations set at equal intervals along the tire circumferential direction. As shown in FIGS. 3 and 4, the pair of wear degree indication grooves 11 and 12 extend in parallel to each other. These wear degree display grooves 11 and 12 have the same shape and the same length when the tread surface of the tread portion 1 is viewed from directly above. Each wear degree display groove 11 is formed to have a constant depth, but each wear degree display groove 12 is formed so that the depth gradually changes along the longitudinal direction. More specifically, the depth of the wear degree display groove 12 is gradually increased from one end portion 12a toward the other end portion 12b.

  When the pneumatic tire configured as described above is mounted on a racing car and a race is performed, the degree of wear of the tread portion 1 is determined based on the pair of wear degree display grooves 11 and 12 in the pit. In the pneumatic tire of the present embodiment, a pair of wear degree display grooves 11 and 12 extending in parallel with the tread portion 1 are provided, and one of the wear degree display grooves 11 is formed to have a constant depth, and the other Since the wear degree display groove 12 is formed so that the depth gradually changes along the longitudinal direction, the length of the wear degree display groove 12 changes as wear progresses. The length does not change. Therefore, the length change of the wear degree display groove 12 is grasped using the length of the wear degree display groove 11 as an index, and the degree of wear of the tread portion 1 is instantaneously determined based on the change in the length of the wear degree display groove 12. It can be judged accurately. For example, in FIG. 5, about 50% of the entire length of the wear degree display groove 12 is lost due to wear, which indicates 50% wear with respect to the total wear. Accordingly, when 50% wear is used as an index for tire replacement at the time of pit-in, it is possible to determine the necessity of tire replacement smoothly by instantaneously judging the degree of wear.

  Further, each of the wear degree display grooves 11 and 12 is a series of thin grooves and does not require a large depression or a large number of depressions, so that the influence on various performances of the pneumatic tire can be minimized. For example, when a large depression or a large number of depressions are formed in the tread portion 1, it itself becomes a cause of uneven wear, or traveling performance or the like deteriorates due to a decrease in the contact area. When the wear degree display grooves 11 and 12 are provided, such inconvenience does not occur.

  In the pneumatic tire, it is desirable that the pair of wear degree display grooves 11 and 12 have the same shape and the same length when the tread surface of the tread portion 1 is viewed from directly above. Thereby, since the comparison of the wear degree display grooves 11 and 12 becomes easy, the length change of the wear degree display groove 12 can be grasped more accurately. However, even when the shape or length of the pair of wear degree display grooves 11 and 12 is different, if the wear degree display grooves 11 and 12 extend in parallel, the two can be compared. . In addition, it is desirable that the pair of wear degree display grooves 11 and 12 extend in parallel to each other, but it is not necessarily required to be parallel if the lengths of the two can be compared.

  Moreover, the mutual space | interval G of a pair of abrasion degree display groove | channels 11 and 12 is good to exist in the range of 2 mm <= G <= 10mm. Thereby, since the comparison of the wear degree display grooves 11 and 12 becomes easy, the length change of the wear degree display groove 12 can be grasped more accurately. If the mutual distance G between the two is too small, cracks are likely to occur between the pair of wear degree display grooves 11 and 12, and conversely if too large, the comparison between the two becomes difficult. It is preferable that the pair of wear degree display grooves 11 and 12 have the mutual distance G in the above range over the entire length thereof.

  In the pneumatic tire, the pair of wear degree display grooves 11 and 12 may be disposed at a plurality of locations in the tire circumferential direction, particularly at least 6 locations in the tire circumferential direction. Thereby, the wear degree display grooves 11 and 12 can be easily found. Therefore, even in a vehicle covered with a cowl, such as a racing car, where the tires are difficult to see, the wear degree display grooves 11 and 12 can be easily confirmed, and the degree of wear of the tread portion 1 can be determined instantaneously and accurately. can do. Of course, it is also possible to arrange the pair of wear degree display grooves 11 and 12 at only one place in the tire circumferential direction.

  The pair of wear degree display grooves 11 and 12 may be disposed at a plurality of locations in the tire width direction, particularly at least 3 locations in the tire width direction. In this case, in a vehicle with a camber angle or a vehicle in which a pneumatic tire is set to a low internal pressure, uneven wear such as center wear and shoulder wear can be determined instantaneously and accurately. In particular, when the pair of wear degree display grooves 11 and 12 are arranged in at least three locations in the tire width direction including both the shoulder portions and the center portion, it is easy to determine uneven wear. Of course, it is also possible to arrange the pair of wear degree display grooves 11 and 12 only at one place in the tire width direction.

  FIG. 6 shows a modification of the pair of wear degree display grooves. In FIG. 6, the wear degree display groove 11 is formed so that the depth is constant, and the wear degree display groove 12 is formed so that the depth gradually changes along the longitudinal direction. The depth gradually increases from one end 12a toward the other end 12b. In addition, a protrusion 13 having a peak at the center position in the depth direction of the wear degree display groove 11 is formed at the center position in the longitudinal direction of the wear degree display groove 11. Also in this case, as in the above-described example, when wear progresses, the length of the wear degree display groove 12 changes, and the degree of wear of the tread portion 1 is determined instantaneously and accurately based on the change in length. Can do. Moreover, since the protrusion 13 of the wear degree display groove 11 appears on the tread when 50% worn, the protrusion 13 can be used as an index of the change in the length of the wear degree display groove 12. Such protrusions 13 may be provided at other positions in the longitudinal direction of the wear degree display groove 11, or a plurality of protrusions 13 may be provided for one wear degree display groove 11. Also good.

  FIG. 7 shows another modification of a pair of wear degree display grooves. In FIG. 7, the pair of wear degree display grooves 11 and 12 extend in parallel with each other, and the shape when the tread surface of the tread portion 1 is viewed from directly above is a wave shape. The wear degree display groove 11 is formed to have a constant depth, and the wear degree display groove 12 is formed so that the depth gradually changes along the longitudinal direction. Is gradually increased from one end 12a to the other end 12b. Also in this case, as in the above-described example, when wear progresses, the length of the wear degree display groove 12 changes, and the degree of wear of the tread portion 1 is determined instantaneously and accurately based on the change in length. Can do.

  FIG. 8 shows a state in which the other wear degree display groove is cut out in the longitudinal direction. In the pneumatic tire, the ratio of the wear amount D1 to the maximum depth D0 of the other wear degree display groove 12 (D1 / D0 × 100%) and the ratio of the disappearance amount L1 to the total length L0 of the other wear degree display groove 12 ( L1 / L0 × 100%) is preferably proportional to the depth of the other wear degree display groove 12 along its longitudinal direction. For example, in a wear state where the ratio of the wear amount D1 to the maximum depth D0 of the wear degree display groove 12 is A%, it is ideal that the ratio of the disappearance amount L1 to the total length L0 of the wear degree display groove 12 is A%. is there. However, in the present invention, if the error with respect to A% is within ± 5% point, the proportional relationship is established.

  In the pneumatic tire, the thickness W (see FIG. 4) of the wear degree display grooves 11 and 12 is preferably in the range of 0.5 mm ≦ W ≦ 2.0 mm. Thereby, the influence on various performances of the pneumatic tire can be minimized while ensuring the visibility of the wear degree display grooves 11 and 12. Here, if the thickness W of the wear level display grooves 11 and 12 is smaller than 0.5 mm, the wear level display grooves 11 and 12 become difficult to see. The tire performance will be affected.

  The length L (see FIG. 4) of the wear degree display grooves 11 and 12 is preferably in the range of 5 mm ≦ L ≦ 15 mm. When the length L of the wear degree display grooves 11 and 12 is removed, it becomes difficult to accurately grasp the change in the length of the other wear degree display groove 12 using the length of the one wear degree display groove 11 as an index.

  In the embodiment described above, the slick tire for racing has been described, but the present invention can also be applied to a pneumatic tire used for purposes other than racing.

In a pneumatic tire having a tire size of 330 / 710R18, tires of conventional examples, test examples 1 to 5 and comparative examples 1 and 2 in which a wear degree display unit is provided in a tread portion were manufactured.

  In the conventional tire, a cylindrical wear degree display hole is provided in the tread portion as wear degree display means, and the wear degree display holes are installed at four places in the tire circumferential direction and four places in the tire width direction. The wear degree indicating hole has a diameter of 4 mm and a depth of 4 mm.

The tires of Test Examples 1 to 5 are provided with a pair of wear degree display grooves (FIG. 3) extending in parallel as wear degree display means in the tread portion, and one of the wear degree display grooves has a constant depth. The other wear degree display groove is formed so that the depth gradually changes along the longitudinal direction, the number of the pair of wear degree display grooves installed in the tire circumferential direction, and the pair of wear degree display groove tires. The number of installations in the width direction and the thickness of each wear degree display groove are set as shown in Table 1. In addition, the mutual space | interval of a pair of wear degree display groove | channel was 5 mm, and the length of each wear degree display groove | channel was 10 mm.

  In the tire of Comparative Example 1, a pair of wear degree display grooves extending in parallel as wear degree display means are provided in the tread portion, and the depth of the pair of wear degree display grooves is constant. The mutual interval and length of the wear degree display grooves were set in the same manner as described above.

  The tire of Comparative Example 2 is provided with rubber columns made of a plurality of rubber layers having different colors along the depth direction as wear degree display means in the tread portion, and these rubber columns are arranged at four locations in the tire circumferential direction and in the tire width direction. Are installed at four locations. The rubber column has a diameter of 4 mm, a depth of 4 mm, and is formed by laminating blue, yellow, and red rubber layers.

  For these test tires, the time required to confirm the degree of wear, the accuracy of confirming the degree of wear, the accuracy of confirming the uneven wear, and the resistance to uneven wear were evaluated by the following evaluation methods, and the results are also shown in Table 1. It was.

Time required to confirm wear:
Each test tire is mounted on a wheel with a rim size of 18 × 13 J and mounted on a racing car with a displacement of 3800 cc with an air pressure of 180 kPa. We checked the degree and measured the time required. This measurement was performed by 10 workers, and the average value of the measurement time was obtained.

Accuracy of wear confirmation:
The difference between the degree of wear (%) estimated in the above-described wear degree confirmation work and the actual degree of wear (%) was obtained, and the sum of the differences among the 10 workers was obtained. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the sum of the differences. The larger the index value, the higher the accuracy of wear level confirmation.

Accuracy of partial wear confirmation:
The difference between the amount of uneven wear (mm) and the actual amount of uneven wear (mm) between the shoulder portion and the center portion estimated in the above-described wear degree confirmation work is obtained, and the sum of the differences of 10 workers is obtained. Asked. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the sum of the differences. The larger the index value, the higher the accuracy of confirmation of partial wear.

Uneven wear resistance:
After the circuit travel described above, the amount of uneven wear (mm) generated around the wear degree display means was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the uneven wear resistance.

As is clear from Table 1, in the case of Test Examples 1 to 5, in comparison with the conventional example, although the time required to confirm the wear degree is short, the accuracy of wear degree confirmation and the confirmation of uneven wear are confirmed. The accuracy was high, and the uneven wear resistance was good. On the other hand, in the case of the comparative example 1, since the degree of wear cannot be evaluated using the change in the length of the wear degree display groove, the result is the same level as the conventional example. In the case of Comparative Example 2, not only the accuracy of wear degree confirmation and the accuracy of uneven wear confirmation were low, but also uneven wear occurred around the wear degree display means.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 11 One wear degree display groove 12 The other wear degree display groove

Claims (9)

A pair of wear degree display grooves extending in parallel to the tread portion are provided, one of the wear degree display grooves is formed to have a constant depth, and the other of the wear degree display grooves has a depth along the longitudinal direction. The pneumatic tire is characterized by being formed so as to gradually change , and the pair of wear degree display grooves each have a wave shape when the tread surface of the tread portion is viewed from directly above .   2. The pneumatic tire according to claim 1, wherein the pair of wear degree display grooves have the same shape and the same length when the tread surface is viewed from directly above.   3. The pneumatic tire according to claim 1, wherein an interval G between the pair of wear degree display grooves is in a range of 2 mm ≦ G ≦ 10 mm.   The pneumatic tire according to claim 1, wherein the pair of wear degree display grooves are disposed at a plurality of locations in the tire circumferential direction.   5. The pneumatic tire according to claim 4, wherein the pair of wear degree display grooves are disposed in at least six locations in the tire circumferential direction.   The pneumatic tire according to claim 1, wherein the pair of wear degree display grooves are disposed at a plurality of locations in the tire width direction.   The pneumatic tire according to claim 6, wherein the pair of wear degree display grooves are disposed at at least three locations in the tire width direction.   The depth of the other wear degree display groove is set so that the ratio of the wear amount to the maximum depth of the other wear degree display groove is proportional to the ratio of the disappearance amount to the total length of the other wear degree display groove. The pneumatic tire according to claim 1, wherein the pneumatic tire is changed along a longitudinal direction thereof.   The pneumatic tire according to claim 1, wherein a thickness W of each of the pair of wear degree display grooves is in a range of 0.5 mm ≦ W ≦ 2.0 mm.

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