JP5436094B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire including, on a ground contact surface, at least two circumferential main grooves extending in the circumferential direction, a ground contact end, and ribs separated by these circumferential main grooves. The present invention relates to a material that can effectively suppress uneven wear.

  In a pneumatic tire comprising at least two circumferential main grooves extending in the circumferential direction, a grounding end, and ribs separated by the circumferential main grooves on a ground contact surface, one or both of the ribs In some cases, uneven wear may occur in which the side portion of the steel plate wears faster than the central portion. As a countermeasure, it is generally necessary to implement both the suppression of uneven wear nucleation and the suppression of uneven wear progress. However, it is difficult to achieve both of these, for example, suppressing uneven wear nucleation. For this purpose, it is preferable to reduce the rectangular ratio representing the aspect ratio of the ground contact shape, while it is preferable to increase the rectangular ratio for suppressing the progress of uneven wear. In this case, even if there is an optimum point of the rectangular ratio that makes these measures compatible, if it deviates even a little from the optimum point, it becomes impossible to satisfy any of the above measures, and sudden wear resistance performance suddenly There was a problem that would decrease.

  On the other hand, as another countermeasure, there has been proposed a method in which a portion different from a portion where uneven wear occurs is intentionally worn to suppress wear at the uneven wear portion. As shown in FIG. 1, a part of the tread surface of the tire is shown in a sectional view, and a circumferential groove 91 called a defense groove (DF) is provided near the ground contact end 95 of the tread surface 90, The land portion 92 on the outer side in the width direction from the groove 91 is intentionally worn to suppress the wear on the rib 93 on the inner side in the width direction from the defense groove (see, for example, Patent Document 1).

  Further, as shown in a sectional view of a part of the tread surface of the tire in FIG. 2, in order to prevent early wear of the land portion 83 adjacent to the circumferential main groove 81 disposed on the tread surface 80, the circumferential direction A tire configured such that when a protrusion 82 called a uneven wear sacrificial protrusion (BCR, Braking-Force Control Rib) extending in the circumferential direction in the main groove 81 is arranged and grounded, the protrusion 82 is also grounded. It has been proposed as a countermeasure against the above-mentioned uneven wear. Due to the small diameter of the projection 82 compared to the surrounding land portion 83, the shear stress becomes higher than the surrounding, and the projection 82 consumes wear energy at the expense of the main portion. The wear energy of the land portion 83 adjacent to the groove 81 is reduced to suppress the wear (see, for example, Patent Document 2).

JP 2003-200713 A JP 2008-1114824 A

  However, these conventional wear sacrificial parts are intentionally formed and unevenly worn, so that the effect decreases with the progress of wear and there is no space for providing the wear sacrificial parts. Therefore, there was a possibility that it had to be made smaller and therefore disappeared early.

  The present invention has been made in view of such problems, and prevents the wear sacrificial portion from disappearing immediately as the overall wear progresses, while suppressing uneven wear in the periphery in a very small space. An object of the present invention is to provide a pneumatic tire that can be used.

<1> is a pneumatic tire including, on the ground contact surface, at least two circumferential main grooves extending in the circumferential direction, a ground contact end, and ribs separated by the circumferential main grooves.
At least one of the ribs is provided with an uneven wear sacrificial groove, and the uneven wear sacrificial groove is made shallower than the circumferential main groove separating the ribs. It is configured so that at least a part is in contact with the road surface under the specified conditions with a specified internal pressure and a specified load applied .
The uneven wear sacrificial groove is provided in a rib adjacent to the ground contact end, and the uneven wear sacrificial groove is orthogonal to the tire central axis, which is separated from the center in the width direction of the rib by 10% of the land portion width on the left and right sides. A pneumatic tire characterized in that a groove center is arranged in a region sandwiched between two surfaces .

  <2> is that in <1>, the uneven wear sacrificial projection protruding from the groove bottom is disposed in the uneven wear sacrificial groove, and the uneven wear sacrificial protrusion is grounded to the road surface under the specified conditions. It is a pneumatic tire characterized by comprising.

  <3> is the main groove uneven wear sacrificial protrusion protruding from the groove bottom in at least one of the circumferential main grooves that divides the rib in which the uneven wear sacrifice groove is disposed in <1> or <2>. The main groove uneven wear sacrificial projection is made lower than the bottom of the uneven wear sacrificial groove or, if the uneven wear sacrificial groove has the uneven wear sacrificial protrusion, lower than the top of the uneven wear sacrificial protrusion. This is a pneumatic tire.

< 4 > is any one of < 1> to <3> , wherein a narrow groove for preventing edge wear progress is provided between the uneven wear sacrificial groove and the ground contact end, and the narrow groove for preventing edge wear progress is provided. A pneumatic tire characterized in that the outer edge in the tire width direction is an edge wear sacrificial rib.

According to <1>, at least one of the ribs is provided with a partial wear sacrificial groove, and the partial wear sacrificial groove is shallower than the circumferential main groove that divides the rib, and in a new state without wear, Since the tire is attached to the specified rim, the specified internal pressure is filled and the specified load is applied, and at least a part of the tire is in contact with the road surface, so if the groove bottom becomes deeper, the groove bottom will not function as a sacrificial wear part. When the periphery wears and the groove becomes shallower, it begins to function again, and at this point, it does not disappear quickly, and since only a recessed groove is provided in the rib, a large space for wear sacrifice is not required.
Further, the uneven wear sacrificial groove is provided in a rib adjacent to the ground contact end, and the uneven wear sacrificial groove is orthogonal to the tire central axis, separated from the center in the width direction of the rib by 10% of the land portion width on the left and right sides. Since the groove center is disposed in the region sandwiched between the two surfaces, particularly the occurrence of significant uneven wear can be effectively suppressed on both sides in the width direction of the rib adjacent to the ground contact end.

  According to <2>, the uneven wear sacrificial protrusion protruding from the groove bottom is disposed in the uneven wear sacrificial groove, and the uneven wear sacrificial protrusion is configured to contact the road surface under the specified conditions. The wear volume can be increased, and the progression of uneven wear can be delayed.

  According to <3>, a main groove uneven wear sacrificial protrusion protruding from the groove bottom is disposed in at least one of the circumferential main grooves that divides the rib in which the uneven wear sacrifice groove is disposed. Since the uneven wear sacrificial projection is lower than the groove bottom of the uneven wear sacrificial groove, or when the uneven wear sacrificial groove has the uneven wear sacrificial protrusion, the uneven wear sacrificial groove is lower. By preferentially wearing, the progress of wear of the main groove uneven wear sacrificial projection can be delayed, and the progress of uneven wear of the land portion adjacent to the main groove can be delayed for a long period of time.

According to < 4 >, an edge wear sacrificial narrow groove is provided between the uneven wear sacrificial groove and the ground contact end, and an edge wear sacrificial rib is provided on the outer side in the tire width direction of the edge wear progress preventing narrow groove. Therefore, the wear of the edge wear sacrificial rib can be delayed by preferentially wearing the uneven wear sacrificial groove.

It is sectional drawing which shows the tread surface of the conventional pneumatic tire provided with the defense groove. It is sectional drawing which shows the tread surface of the conventional pneumatic tire provided with BCR. It is sectional drawing which shows the pneumatic tire of embodiment which concerns on this invention in the state of non-grounding. It is sectional drawing shown in the state which earth | grounded the pneumatic tire of embodiment which concerns on this invention. It is a graph which shows typically distribution of peripheral direction shearing force at the time of ground contact by a width direction position of a shoulder rib. It is sectional drawing which shows the pneumatic tire of the modification of embodiment. It is sectional drawing which shows the pneumatic tire of the other modification of embodiment. It is sectional drawing which shows the pneumatic tire of the modifications other than the above of embodiment. It is sectional drawing which shows the pneumatic tire of the modifications other than the above of embodiment. It is sectional drawing which shows the pneumatic tire of the modifications other than the above of embodiment. It is sectional drawing for demonstrating the amount of uneven wear, and a wear rate. It is a graph which shows the relationship between a wear rate and the amount of partial wear. It is sectional drawing which shows the pneumatic tire of a comparative example.

  A pneumatic tire according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 3 is a cross-sectional view in the width direction showing the tread surface of the tire of this embodiment. The pneumatic tire 10 has at least two circumferential main grooves 1 (in FIG. 3) extending in the circumferential direction on the ground contact surface 31. Only one) and ribs 3 separated by the circumferential main grooves 1 or by the grounding end 5 and the circumferential main groove 1a as shown.

  The pneumatic tire 10 of the present invention is characterized in that a partial wear sacrificial groove 4 is provided in at least one rib 3 among the plurality of ribs 3, and this partial wear sacrificial groove 4 is in a new state that does not wear. 4, the tire 10 is mounted on a specified rim, filled with a specified internal pressure, and at least partially in contact with the road surface under specified conditions, as shown in the cross-sectional view in the width direction of the tread surface. In the illustrated case, such a partial wear sacrificial groove 4 is disposed in a shoulder rib 3a defined by a ground contact end 5 and a circumferential main groove 1a adjacent thereto.

  In the present specification, the specified load, the specified internal pressure, and the specified rim are as follows. In other words, the specified load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the specified industry standard, and the specified internal pressure is the single wheel at the applicable size described in the standard. The air pressure corresponding to the maximum load (maximum load capacity), and the specified rim is a standard rim (or “Approved Rim”, “Recommended Rim”) in the applicable size described in the standard. For such industrial standards, there are standards that are valid for each region where tires are produced or used. For example, in the United States, “The Tire and Rim Association Inc. YEAR BOOK” (including design guides) ) In Europe according to the “The European Tire and Rim Technical Organization Standard Manual” and in Japan according to the “JATMA Year Book” of the Two-Tire Automobile Tire Association.

  The operation of the present invention will be described taking as an example the case where the uneven wear sacrificial groove 4 is provided in the shoulder rib 3a, which is particularly effective. The shoulder rib 3a is likely to be unevenly worn at both the outer and inner rib ends 6 and 7 in the width direction, and is less likely to be unevenly worn at the central portion 8 in the width direction of the rib. The basic idea of the present invention is to suppress or alleviate the uneven wear at the rib end portion by providing a center of uneven wear intentionally at the central portion and consuming the wear energy at this portion.

  A typical uneven wear factor in the shoulder rib 3a is the progress of self-excited wear due to the braking force, and by providing a diameter difference between the uneven wear sacrificial groove 4 and the periphery of the rib end portions 6, 7 and the like, FIG. 5 schematically shows the distribution of the circumferential shear force at the time of ground contact depending on the position of the shoulder rib 3a in the width direction. If there is no uneven wear sacrificial groove 4, the circumferential shear force is the rib width. The line A is expressed as a substantially uniform line A, but when the uneven wear sacrificial groove 4 is provided, the braking force concentrates on the uneven wear sacrificial groove 4, so that the portions other than the uneven wear sacrificial groove 4 are formed. Due to the reduced load of the braking force, a line B is obtained, and the circumferential shear force increases in the portion of the uneven wear sacrificial groove 4 and is reduced in the other portions. Fast progress and rib In part 6, 7 becomes slow.

  Further, it is preferable that the uneven wear sacrificial groove 4 has a depth d1 of 20% or less of the depth d2 of the circumferential main groove 1a. In this way, the shoulder rib 3a wear is provided by providing the groove 4. There is no significant contribution to volume reduction.

  Furthermore, even if the wear rate exceeds 20% and the initial depth of the uneven wear sacrificial groove 4 is worn away, uneven wear nuclei are formed at the center of the rib at that point. The effect can be maintained as a partial wear sacrificial groove until the degree is reached.

  Furthermore, it can be combined with the structure provided with the DF or BCR described as the prior art, and in this case, the effect of providing the DF or BCR is reduced by reducing the burden of the braking force at the rib end. Can increase or contribute to life extension.

  The modification of embodiment of this invention is shown below. 6 and 7 are cross-sectional views showing an example in which the uneven wear sacrificial groove of the embodiment of FIG. 3 is made asymmetric in the tire width direction. The uneven wear sacrificial groove 4a shown in FIG. It is composed of a wall surface that has a gentle central side in the direction, and as a whole, the groove bottom faces outward in the tire width direction. Conversely, the uneven wear sacrificial groove 4b shown in FIG. It consists of a wall surface, and the groove bottom is directed to the center side in the tire width direction as a whole.

  In the modification shown in FIG. 8, a main groove uneven wear sacrificial protrusion 12 that protrudes from the groove bottom 11 is disposed in the groove 1a that delimits the shoulder rib 3a in which the uneven wear sacrifice groove 4 is disposed. The uneven wear sacrificial protrusion 12 is made lower than the groove bottom of the uneven wear sacrifice groove 4 by a. Originally, the conventional technique called BCR has a main groove uneven wear sacrificial projection 12 protruding from the groove bottom 11 in the groove 1a, and the main groove uneven wear sacrificial protrusion 12 is artificially worn. Thus, there is an aim to suppress the progress of uneven wear in the land portion adjacent to the groove 1a, but there has been a possibility that it will disappear earlier due to the speed of the progress of the wear.

  In contrast to such a conventional technique, the modified example shown in FIG. 8 is provided with the uneven wear sacrificial groove 4 in the shoulder rib 3a. In this case, the uneven wear sacrificial groove 4 is preferentially worn, The progress of wear of the main groove uneven wear sacrificial protrusion 12 can be delayed, and the progress of uneven wear of the land portion adjacent to the main groove 1a can be delayed for a long period.

  The modification shown in FIG. 9 uses a wear sacrificial groove 14 having a partial wear sacrificial protrusion 16 that protrudes from the groove bottom 15 instead of the wear sacrificial groove 4 in FIG. The uneven wear sacrificial protrusion 16 is configured to contact the road surface. Further, as shown in this example, when the uneven wear sacrificial protrusion 16 is provided in the wear sacrifice groove 14 and the main groove uneven wear sacrifice protrusion 12 is provided in the main groove 1a, The top surface of the main groove uneven wear sacrificial protrusion 12 is made lower than the top surface (only b), and the groove bottom 15 of the wear sacrifice groove 14 is made shallower than the groove bottom 11 of the main groove 1a (only c). In this case, the wear volume of the wear sacrificial groove 14 can be increased by the uneven wear sacrificial protrusion 16, and the period for delaying the progress of the partial wear of the wear sacrificial groove 14 at both ends of the shoulder rib 3 a is lengthened accordingly. In addition, the wear of the main groove uneven wear sacrificial protrusion 12 can also be delayed.

  FIG. 10 shows that an edge wear progress prevention narrow groove 17 called a defense groove is provided between the wear sacrifice groove 14 and the ground contact end 5 in FIG. The edge wear sacrificial rib 18 is artificially worn by providing the edge wear progress preventing narrow groove 17 even if the wear sacrificial groove 14 is not originally provided. The partial wear of the shoulder rib 3a is delayed, but the wear of the edge wear sacrifice rib 18 can be delayed by preferentially wearing the uneven wear sacrifice groove 14.

  FIG. 3 shows the first embodiment, FIG. 8 shows the second embodiment, FIG. 9 shows the third embodiment, FIG. 10 shows the fourth embodiment, and FIG. The shoulder rib 93 between the main groove 94 and the ground contact edge 95 is a comparative example of a conventional tire 90A in which no wear sacrificial groove is provided, and these tires are used as front wheels of the bus. It was installed and run on a real vehicle, the progress of wear was checked, and the amount of uneven wear when the wear rate was 80% was compared. The size of the tire used was 12R22.5. The results are shown graphically in FIG.

  With reference to the cross-sectional view of FIG. 11, the wear rate refers to the ratio of the dimension d, which is the amount of wear of the groove, to the original depth d2 of the main groove 1a. The cross-sectional area of 22 is referred to, and in the graph of FIG. The smaller the value, the smaller the uneven wear and the better.

DESCRIPTION OF SYMBOLS 1, 1a Circumferential main groove 3 Rib 3a Shoulder rib 4 Uneven wear sacrifice groove 5 Grounding end 6, 7 Rib end 10 Pneumatic tire 11 Groove bottom of circumferential main groove 12 Main groove uneven wear sacrifice protrusion 14 Uneven wear sacrifice Groove 15 Groove bottom of uneven wear sacrificial groove 16 Uneven wear sacrificial protrusion of uneven wear sacrificial groove 17 Narrow groove for preventing edge wear progress 18 Edge wear sacrificial rib 21, 22 Uneven wear portion 31 Ground surface

Claims (4)

In a pneumatic tire comprising, on the ground contact surface, at least two circumferential main grooves extending in the circumferential direction, a ground contact end, and ribs separated by these circumferential main grooves,
At least one of the ribs is provided with a partial wear sacrificial groove, and the groove depth of the partial wear sacrificial groove is shallower than the circumferential main groove separating the rib, and the tire is defined in a new state without wear. It is constructed so that it is attached to the rim and filled with the specified internal pressure, and at least part of it is in contact with the road surface under specified conditions with a specified load applied .
The uneven wear sacrificial groove is provided in a rib adjacent to the ground contact end, and the uneven wear sacrificial groove is orthogonal to the tire central axis, which is separated from the center in the width direction of the rib by 10% of the land portion width on the left and right sides. A pneumatic tire characterized in that a groove center is arranged in a region sandwiched between two surfaces .   The uneven wear sacrificial protrusion protruding from the groove bottom is disposed in the uneven wear sacrifice groove, and the uneven wear sacrificial protrusion is configured to contact the road surface under the specified conditions. Pneumatic tire described in 2.   A main groove uneven wear sacrificial protrusion protruding from the groove bottom is disposed on at least one of the circumferential main grooves that divides the rib in which the uneven wear sacrifice groove is disposed, and the main groove uneven wear sacrificial protrusion is 3. The lower side of the uneven wear sacrificial groove, or when the uneven wear sacrificial groove has a partial wear sacrificial protrusion, the height is lower than the top of the uneven wear sacrificial protrusion. Pneumatic tire. A narrow groove for preventing edge wear progress is provided between the uneven wear sacrificial groove and the ground contact end, and an outer edge in the tire width direction of the narrow groove for preventing edge wear progress is used as an edge wear sacrificial rib. The pneumatic tire according to any one of claims 1 to 3 .

Images