JP6225068B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that achieves both wet performance and wear resistance.

  The following Patent Document 1 proposes a racing cart tire in which the groove width of the groove provided in the tread portion and the surface area of the tread surface of each block divided by the groove are improved. This tire is expected to have an effect of improving the road surface followability of the tread portion, and particularly improving the grip performance on the wet road surface, by flexibly bending the middle block divided into the tread portion.

JP 2012-116245 A

  However, since the racing cart tire of the cited document 1 is relatively small in each block provided in the tread portion, it has low wear resistance, such as steering stability and significant abrasion in each block. There was a problem.

  The main object of the present invention is to provide a pneumatic tire having high wear resistance while maintaining wet performance.

  The present invention includes a center main groove extending in a zigzag shape continuously in the tire circumferential direction in the tread portion, a plurality of first lateral grooves extending from the center main groove to at least the first tread end, and at least from the center main groove. A pneumatic tire provided with a plurality of second lateral grooves extending to the second tread end, wherein each of the first lateral groove and the second lateral groove extends in the tire axial direction from the center main groove. Between the first lateral grooves adjacent to each other in the tire circumferential direction, and the center main groove and the first tread end. Between the second lateral grooves adjacent to each other in the tire circumferential direction is between the center main groove and the second tread end in the tire axial direction. It is characterized in that a second successive blocks is partitioned.

  In the pneumatic tire of the present invention, it is preferable that the tire circumferential direction length of the first lateral groove is larger than the arrangement pitch of the first lateral groove in the tire circumferential direction.

  In the pneumatic tire of the present invention, it is preferable that the tire circumferential direction length of the second lateral groove is larger than the arrangement pitch of the second lateral groove in the tire circumferential direction.

  In the pneumatic tire of the present invention, the inclined portion of the first lateral groove and the inclined portion of the second lateral groove are arranged on the inner inclined portion on the axial direction side and on the outer side in the tire axial direction, and on the inner inclined surface. It is desirable to include an outer inclined portion having a smaller angle with respect to the tire axial direction than the portion.

  In the pneumatic tire of the present invention, it is preferable that the axial direction portion, the inner inclined portion, and the outer inclined portion are all linear.

  In the pneumatic tire according to the aspect of the invention, the first lateral groove extends from a first protrusion that projects toward the first tread end side of the center main groove, and the second lateral groove includes the second tread of the center main groove. It is desirable that the second protrusion protrudes toward the end side.

  The pneumatic tire according to the present invention includes a center main groove extending in a zigzag shape continuously in the tire circumferential direction in the tread portion, a plurality of first lateral grooves extending from the center main groove to at least the first tread end, and the center main groove. A plurality of second lateral grooves extending from at least to the second tread end. The center main groove, the first lateral groove, and the second lateral groove form a continuous drainage path from the center portion of the tread portion to the first tread end and the second tread end, so that sufficient wet performance is exhibited. .

  Each of the first transverse groove and the second transverse groove includes an axial portion extending along the tire axial direction from the center main groove, and an inclined portion that is continuous with the axial portion and is inclined with respect to the tire axial direction. . Since a large contact pressure acts on the axial portion, an excellent edge effect is exhibited in the tire circumferential direction during wet running. Therefore, the traction performance during wet traveling is improved.

  The inclined portion effectively discharges water in the center main groove and the axial direction portion to the outer side in the tire axial direction during wet running. Moreover, the inclined portion exhibits an edge effect in the tire axial direction, and in particular, the turning performance on a wet road surface is enhanced.

  Between the first lateral grooves adjacent to each other in the tire circumferential direction, a first block continuous in the tire axial direction is partitioned between the center main groove and the first tread end. Between the second lateral grooves adjacent to each other in the tire circumferential direction, a second block continuous in the tire axial direction is partitioned between the center main groove and the second tread end. Since the first block and the second block are continuous in the tire axial direction between the center main groove and the tread end, deformation at the time of ground contact is suppressed compared with the conventional block, and thus excellent wear resistance. Sex is demonstrated.

  As described above, the pneumatic tire of the present invention can provide good wet performance and wear resistance.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. It is an enlarged view of the left side of the tread part of FIG. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The tire 1 of the present embodiment is suitably implemented for a racing cart having an outer diameter of 300 mm or less, for example. The tire 1 of the present embodiment is particularly for wet use that is suitably worn during rainy weather. However, the present invention is not limited to such an embodiment.

  The tire 1 includes, for example, a tread pattern in which the rotation direction R is designated. The rotation direction R is displayed by, for example, characters or marks on a sidewall portion or the like.

  As shown in FIG. 1, the tread portion 2 is provided with a center main groove 10, a first lateral groove 21, and a second lateral groove 22.

  The center main groove 10 is provided, for example, in the central portion of the tread portion 2 and passes on the tire equator C in a preferred embodiment.

  The center main groove 10 extends in a zigzag shape continuously in the tire circumferential direction. The center main groove 10 includes, for example, a first groove portion 11 inclined to one side with respect to the tire circumferential direction and a second groove portion 12 inclined in the direction opposite to the first groove portion 11. The center main groove 10 is formed by alternately providing the first groove portions 11 and the second groove portions 12 in the tire circumferential direction, and does not have a groove portion extending along the tire circumferential direction. Such a center main groove 10 suppresses a decrease in rigidity of the tread portion 2 in the tire axial direction, and improves steering stability.

  Each of the first groove portion 11 and the second groove portion 12 extends linearly. An angle θ1 of the first groove portion 11 and the second groove portion 12 with respect to the tire circumferential direction is, for example, 10 to 30 °. The center main groove 10 including the first groove portion 11 and the second groove portion 12 exhibits an edge effect with respect to the tire circumferential direction, and improves the traction performance during wet running.

  The center main groove 10 is provided with the first groove portion 11 and the second groove portion 12, so that the first protrusion 13 protruding toward the first tread end Te1 and the second protrusion protruding toward the second tread end Te2 are provided. 14 and so on.

  The first tread end Te1 and the second tread end Te2 are determined as the outermost contact ends in the tire axial direction when a normal load is applied to the tire 1 in a normal state and contacted to a plane with a camber angle of 0 degrees.

  The “normal state” is an unloaded state in which a normal rim is assembled with a normal rim and filled with a normal internal pressure. Unless otherwise specified, the dimensions and the like of each part of the tire are values in the normal state.

  The “regular rim” is a rim determined for each tire in a standard system including a standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, Or ETRTO means “Measuring Rim”. If there is no applicable standard, the “regular rim” is a rim recommended by the manufacturer.

  The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for JATMA and “TRAI LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA. In the case of ETRTO, it means “INFLATION PRESSURE”, but if there is no applicable standard, it is the internal pressure recommended by the manufacturer. However, the normal internal pressure is 100 kPa when the tire is used for a racing cart.

  The “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” indicates “maximum load capacity”, and TRA indicates “TIRE” The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in the case of ETRTO. However, the normal load is 392 N when the tire is used for a racing cart.

  The groove width W1 of the center main groove 10 is, for example, 3.5 to 7.0% of the tread ground contact width TW. Such a center main groove 10 maintains the rigidity of the central portion of the tread portion 2 while maintaining wet performance, and exhibits excellent wear resistance. The center main groove 10 of the present embodiment extends, for example, with a substantially constant groove width.

  The tread contact width TW is a distance in the tire axial direction between the first tread end Te1 and the second tread end Te2 in a normal state.

  The first lateral groove 21 extends from the center main groove 10 to the first tread end Te1. For example, the first lateral groove 21 of the present embodiment extends from the first protrusion 13.

  The second lateral groove 22 extends from the center main groove 10 to the second tread end Te2. For example, the second lateral groove 22 of the present embodiment extends from the second protrusion 14.

  The center main groove 10 and the first and second lateral grooves form a continuous drainage path from the central portion of the tread portion 2 to the first tread end Te1 and the second tread end Te2, so that sufficient wet performance is achieved. Is demonstrated.

  Each of the first lateral groove 21 and the second lateral groove 22 includes an axial direction portion 24 extending from the center main groove 10 along the tire axial direction, and an inclined portion 25 inclined with respect to the tire axial direction.

  FIG. 2 shows an enlarged view of the left side of the tread portion 2 of FIG. 1, and shows an enlarged view of the axial direction portion 24 and the inclined portion 25 of the first lateral groove 21.

  As shown in FIG. 2, the axial portion 24 extends along the tire axial direction. The axial direction part 24 of this embodiment is parallel to a tire axial direction, for example. Since a large contact pressure acts on the axial portion 24, an excellent edge effect in the tire circumferential direction is exhibited during wet running. Therefore, the traction performance during wet traveling is improved.

  The angle θ2 (not shown) of the axial direction portion 24 with respect to the tire axial direction is not limited to the present embodiment, and for example, the above-described effect can be expected if the angle is 10 ° or less.

  The groove width W2 of the axial portion 24 is preferably 5 mm or more, more preferably 8 mm or more, preferably 15 mm or less, more preferably 12 mm or less. Such an axial portion 24 achieves both wet performance and wear resistance. The axial direction portion 24 of the present embodiment extends with a substantially constant groove width.

  The length L5 of the axial portion 24 in the tire axial direction is preferably 10% or more of the tread contact width TW, more preferably 13% or more, preferably 20% or less, more preferably 17% or less. The length L5 means, for example, the length from the tire equator C to the outer end 24e of the center line 24c of the axial direction portion 24.

  The inclined portion 25 continues to the outer side in the tire axial direction of the axial portion 24. The inclined portion 25 is inclined with respect to the tire axial direction. The inclined portion 25 of the present embodiment is inclined toward the first tread end Te1 side toward the rear arrival side in the rotation direction R. Such an inclined portion 25 effectively discharges water in the center main groove 10 and the axial direction portion 24 to the outer side in the tire axial direction during wet traveling. In addition, the inclined portion 25 exhibits an edge effect in the tire axial direction, and in particular, the turning performance on a wet road surface is enhanced.

  The inclined portion 25 includes an inner inclined portion 26 disposed on the axial direction portion 24 side and an outer inclined portion 27 disposed on the outer side in the tire axial direction.

  The inner inclined portion 26 extends linearly at an angle θ3 of 60 to 80 ° with respect to the tire axial direction, for example. Such an inner inclined portion 26 exhibits an excellent edge effect with respect to the tire axial direction while guiding water in the lateral groove outward in the tire axial direction during wet traveling.

  In order to achieve both wet performance and wear resistance, the groove width W3 of the inner inclined portion 26 is preferably 5 mm or more, more preferably 8 mm or more, preferably 15 mm or less, more preferably 12 mm or less.

  The distance L6 in the tire axial direction from the outer end 26e of the inner inclined portion 26 to the tire equator C is preferably 0.2 times or more, more preferably 0.25 times or more the tread contact width TW (shown in FIG. 1). Yes, preferably 0.35 times or less, more preferably 0.3 times or less. Such an inner inclined portion 26 improves wet performance and wear resistance in a well-balanced manner. The outer end 26e means, for example, the outer end of the center line 26c of the inner inclined portion 26 in the tire axial direction.

  The outer inclined portion 27 is inclined in the same direction as the inner inclined portion 26 and extends linearly at an angle θ4 smaller than the inner inclined portion 26 with respect to the tire axial direction.

  The angle θ4 of the outer inclined portion 27 with respect to the tire axial direction is preferably 5 ° or more, more preferably 10 ° or more, preferably 25 ° or less, more preferably 20 ° or less. Such an outer inclined portion 27 increases the rigidity in the tire axial direction of the land portion in the vicinity of the first tread end Te1 while maintaining wet performance.

  As shown in FIG. 1, the first lateral groove 21 and the second lateral groove 22 have substantially symmetrical shapes at the tire equator C. For this reason, the second lateral groove 22 includes the axial direction portion 24, the inner inclined portion 26, and the outer inclined portion 27 described above, similarly to the first lateral groove 21.

  A first block 31 that is continuous in the tire axial direction is divided between the center main groove 10 and the first tread end Te1 between the first lateral grooves 21 that are adjacent to each other in the tire circumferential direction. A second block 32 that is continuous in the tire axial direction is divided between the center main groove 10 and the second tread end Te2 between the second lateral grooves 22 adjacent to each other in the tire circumferential direction.

  Since the first block 31 and the second block 32 are continuous in the tire axial direction between the center main groove 10 and the tread end, deformation at the time of contact is suppressed as compared with the conventional block. As a result, excellent wear resistance is exhibited.

  As shown in FIG. 2, the first block 31 includes an inner block piece 34 between the axial portions 24, 24, an outer block piece 35 between the outer inclined portions 27, 27, an inner block piece 34, and an outer block piece. 35 and a connecting block piece 36 between them.

  The inner block piece 34 has, for example, a substantially pentagonal shape having an inner edge 34e that protrudes toward the center main groove 10 side. For example, the apex 34t of the inner edge 34e of the present embodiment is provided on the tire equator C. As a result, a large contact pressure acts on the apex 34t, and the water film between the tread portion 2 and the road surface is effectively cut during wet running. For this reason, the hydroplaning phenomenon is suppressed.

  The length L4 in the tire circumferential direction of the inner block piece 34 is preferably 20 mm or more, more preferably 25 mm or more, preferably 40 mm or less, more preferably 35 mm or less. Such an inner block piece 34 achieves a balance between wet performance and wear resistance.

  The outer block piece 35 is provided, for example, straddling the first tread end Te1. The outer block piece 35 includes a first portion 37 on the inner side in the tire axial direction of the first tread end Te1 and a second portion 38 provided on the outer side in the tire axial direction of the first portion 37.

  The first portion 37 of the outer block piece 35 has, for example, a substantially trapezoidal shape divided by the inner inclined portion 26, a pair of adjacent outer inclined portions 27, 27, and the first tread end Te1.

  The second portion 38 of the outer block piece 35 is located, for example, on the outer side in the tire axial direction of the first tread end Te1, and is provided along the buttress portion of the tire. The second portion 38 is provided with the shoulder sub-groove 28, thereby dividing a rectangular horizontally long block piece 39.

  The shoulder sub-groove 28 extends, for example, from the outer side of the first tread end Te1 toward the inner side in the tire axial direction, and terminates in the first portion 37 of the outer block piece 35. The angle θ5 of the shoulder minor groove 28 with respect to the tire axial direction is, for example, 5 to 25 °.

  Such a second portion 38 is easily and repeatedly deformed during traveling, and thus easily generates heat. For this reason, when it starts driving | running | working on a wet road surface, a tread part is raised to appropriate temperature at an early stage, and the outstanding grip performance is obtained. In addition, since the second portion 38 does not substantially contact the road surface, a decrease in steering stability due to the heat generation is effectively suppressed.

  The connection block piece 36 extends obliquely along the inner inclined portion 26. The width W5 perpendicular to the length direction of the connection block piece 36 is preferably 2.0 mm or more, more preferably 3.0 mm or more, preferably 5.0 mm or less, more preferably 4.0 mm or less. Such a connection block piece 36 balances wet performance and wear resistance in a well-balanced manner.

  As shown in FIG. 1, the first block 31 and the second block 32 are substantially symmetrical with each other at the tire equator C. Therefore, the second block 32 has the inner block piece 34, the outer block piece 35, and the connection block piece 36 described above, like the first block 31.

  In order to further exert the above-described effects, it is desirable that the tire circumferential direction length L1 of the first lateral grooves 21 is larger than the arrangement pitch P1 of the first lateral grooves 21 in the tire circumferential direction. Similarly, it is desirable that the tire circumferential direction length L2 of the second lateral grooves 22 is larger than the arrangement pitch P2 of the second lateral grooves 22 in the tire circumferential direction. Such first lateral grooves 21 and second lateral grooves 22 overlap the lateral grooves 20 adjacent in the tire circumferential direction in the tire axial direction, and exhibit excellent wet performance.

  In the first horizontal groove 21 and the second horizontal groove 22 of the present embodiment, for example, the axial direction portion 24, the inner inclined portion 26, and the outer inclined portion 27 are all linearly extended. Thereby, the 1st horizontal groove 21 and the 2nd horizontal groove 22 are bent locally so that the inclination-angle of the groove centerline 20c may change at one point. Thus, during wet running, the groove edge convex portion 29 effectively cuts the water film, and the hydroplaning phenomenon is suppressed.

  3 to 5 are developed views of the tread portion 2 of another embodiment of the present invention. 3 to 5, the same reference numerals are given to the same components as those in the embodiment.

  In the embodiment of FIG. 3, the angle θ1 of the first groove portion 11 and the second groove portion 12 of the center main groove 10 with respect to the tire circumferential direction is larger than that of the embodiment of FIG. Specifically, the angle θ1 of the center main groove 10 of this embodiment is 30 °. Such a center main groove 10 exhibits a more excellent edge effect in the tire circumferential direction.

  In the embodiment of FIG. 4, the groove width W <b> 3 of the inner inclined portion 26 is larger than the groove width W <b> 2 of the axial direction portion 24 and the groove width W <b> 4 of the outer inclined portion 27. Such an inner inclined portion 26 exhibits even better wet performance.

  In the embodiment of FIG. 5, the groove width W3 of the inner inclined portion 26 and the groove width W4 of the outer inclined portion 27 are gradually increased toward the outer side in the tire axial direction. Such inner inclined portion 26 and outer inclined portion 27 enhance wet performance while suppressing uneven wear of the block.

  When the groove widths of the inner inclined portion 26 and the outer inclined portion 27 are gradually increased, the ratio Wmax / Wmin between the maximum width portion Wmax and the minimum width portion Wmin of the inclined portion 25 is, for example, 1.15 to 1.30. is there. Thereby, wet performance and abrasion resistance are improved with good balance.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to illustrated embodiment, It can deform | transform and implement in a various aspect.

A racing cart tire having the basic pattern of FIG. 1 or FIG. 5 was prototyped based on the specifications in Table 1. As a comparative example, as shown in FIG. 6, a tire having a center tread pattern having a linear tread pattern was prototyped. Each test tire was tested for wet performance and wear resistance. The common specifications and test methods for each test tire are as follows.
tire size:
Front wheel: 10 x 4.50-5
Rear wheel: 11 × 6.50-5
Rim size:
Front wheels: 4.5 inches Rear wheels: 6.5 inches Tire internal pressure: 100 kPa for all wheels

<Wet performance>
The following test vehicle equipped with the above test tires was evaluated by the driver's sensation for grip performance during straight traveling and turning when traveling on the following test course consisting of a wet road surface. The results are displayed as an index with the comparative example being 100. It shows that wet performance is excellent, so that a numerical value is large.
Test vehicle: Racing cart equipped with 100cc displacement 2-cycle engine Test course: Asphalt lap course with 1 lap 734m

<Abrasion resistance>
The amount of wear at the center of the tread of each test tire when the test vehicle traveled a certain distance on the circuit course was measured. The result is the reciprocal of the amount of tire wear, and is displayed as an index with the comparative example being 100. It shows that abrasion resistance is excellent, so that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tire of the present invention improved the wear resistance while maintaining the wet performance.

2 tread portion 10 center main groove 21 first lateral groove 22 second lateral groove 24 axial direction portion 25 inclined portion 31 first block 32 second block Te1 first tread end Te2 second tread end

Claims (6)

A center main groove extending zigzag continuously in the tire circumferential direction in the tread portion, a plurality of first lateral grooves extending from the center main groove to at least the first tread end, and at least a second tread end from the center main groove A pneumatic tire provided with a plurality of second lateral grooves extending up to,
Each of the first lateral groove and the second lateral groove includes an axial portion extending along the tire axial direction from the center main groove, and an inclined portion connected to the axial portion and inclined with respect to the tire axial direction. ,
Between the first lateral grooves adjacent to each other in the tire circumferential direction, a first block continuous in the tire axial direction is divided between the center main groove and the first tread end,
A second block continuous in the tire axial direction is divided between the center main groove and the second tread end between the second lateral grooves adjacent to each other in the tire circumferential direction. tire.   The pneumatic tire according to claim 1, wherein a tire circumferential direction length of the first lateral groove is larger than an arrangement pitch of the first lateral groove in the tire circumferential direction.   The pneumatic tire according to claim 1 or 2, wherein a tire circumferential direction length of the second lateral groove is larger than an arrangement pitch of the second lateral groove in the tire circumferential direction.   The inclined portion of the first lateral groove and the inclined portion of the second lateral groove are arranged on the inner inclined portion on the axial direction side, on the outer side in the tire axial direction, and at an angle with respect to the tire axial direction than the inner inclined portion. The pneumatic tire according to any one of claims 1 to 3, including an outer inclined portion having a small diameter.   The pneumatic tire according to claim 4, wherein the axial direction portion, the inner inclined portion, and the outer inclined portion are all linear. The first lateral groove extends from a first protrusion protruding toward the first tread end side of the center main groove,
6. The pneumatic tire according to claim 1, wherein the second lateral groove extends from a second protrusion that protrudes toward the second tread end of the center main groove.

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