JP7418205B2 - pneumatic tires - Google Patents

Description

The present disclosure relates to pneumatic tires.

Pneumatic tires for winter use are required to have traction performance on icy roads.

The pneumatic tire described in Patent Document 1 has a single center block extending over three or more second blocks in the tire circumferential direction. This reduces the groove area at the center of the tread surface in the tire width direction, improving braking performance and turning performance on icy roads. However, regarding the center block, it is beyond the conventional technology except for its length in the tire circumferential direction.

Japanese Patent Application Publication No. 2006-232151

An object of the present disclosure is to provide a pneumatic tire that can improve traction performance on an icy road surface.

The pneumatic tire of the present disclosure includes a center block row in which a plurality of center blocks are arranged in the tire circumferential direction at a central portion of the tread surface in the tire width direction, and a plurality of sipes are formed in the center block, and the tire The width of the center block in the width direction is 55% or more of the half width at ground contact, and the length of the center block in the tire circumferential direction is greater than the width of the center block.

A plan view showing an example of the tread surface of the pneumatic tire of the present disclosure Plan view showing a single center block Schematic diagram showing modified examples of center blocks with different shapes of narrow grooves

Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

FIG. 1 is a developed plan view of a tread surface Tr provided in a pneumatic tire PT (hereinafter also simply referred to as "tire PT") of the present embodiment. The vertical direction in FIG. 1 corresponds to the tire circumferential direction CD , and the horizontal direction in FIG. 1 corresponds to the tire width direction WD . As shown in FIG. 1, the tread pattern formed on the tread surface Tr is a block pattern.

The pneumatic tire PT of this embodiment is a mounting direction specified type tire in which the mounting direction on the vehicle is specified. The arrow OUT points to the outside of the vehicle, and the arrow IN points to the inside of the vehicle. The region on the right side of the tire equator TE in FIG. 1 becomes the outer vehicle mounting region Ao of the tread surface Tr, and the region on the left side of FIG. 1 becomes the inner vehicle mounting region Ai of the tread surface Tr. When the tire PT is mounted on a vehicle, the vehicle mounting outer region Ao is directed toward the outside of the vehicle, and the vehicle mounting inner region Ai is directed toward the inside of the vehicle. The mounting direction is specified, for example, by attaching an indication such as "OUTSIDE" or "INSIDE" to the outer surface of the sidewall portion of the tire PT.

On an icy road surface with a low coefficient of friction, the ground pressure at the center of the tread surface Tr in the tire width direction WD tends to be relatively high. The pneumatic tire PT includes a center block row 10 in which a plurality of center blocks 1 are arranged in the tire circumferential direction CD at the center of the tread surface Tr in the tire width direction WD . In this embodiment, the center block row 10 is provided on the tire equator TE. The tread surface Tr is provided with three main grooves 61 to 63 that extend continuously in the tire circumferential direction CD , of which a pair of main grooves 62 and 63 located across the tire equator TE are located in the center block. Column 10 is divided. The center block row 10 is divided into a plurality of center blocks 1 by lateral grooves 11 extending in the tire width direction WD .

The pneumatic tire PT includes a pair of shoulder block rows 20 and 30 in which a plurality of shoulder blocks 2 and 3 are arranged in the tire circumferential direction CD at both ends of the tread surface Tr in the tire width direction WD. The tire PT also includes a quarter block row 40 in which a plurality of quarter blocks 4 are arranged in the tire circumferential direction CD between the center block row 10 and the shoulder block row 20 on the inner side of the vehicle. In this way, the tread surface Tr is divided into four block rows 10, 20, 30, and 40 by the three main grooves 61 to 63. Although the center block 1, the pair of shoulder blocks 2 and 3, and the quarter block 4 each form a quadrilateral (quadrilateral) in plan view, they are not limited to this, and various shapes can be adopted.

A plurality of sipes 12 are formed in the center block 1. The sipe 12 is formed by a cut having a width of 1.0 mm or less. In order to improve traction performance on an icy road surface, the inclination angle θ12 (see FIG. 2) of the sipe 12 with respect to the tire width direction WD is preferably 45 degrees or less, more preferably 30 degrees or less. Although the sipe 12 is formed as a wave-shaped sipe, it is not limited to this, and may be, for example, a straight sipe. Although both ends of the sipe 12 are closed, one or both ends may be opened into a groove (main grooves 62, 63, lateral groove 11, circumferential narrow groove 13, or widthwise narrow groove 14). The sipe 12 may be a two-dimensional sipe whose shape does not change along the depth direction, or a three-dimensional sipe including a portion whose shape changes along the depth direction.

Sipes 22, 32, and 42 are formed in the shoulder blocks 2 and 3 and the quarter block 4, respectively. In this embodiment, the sipes 12 and 32 arranged in the outer vehicle mounting region Ao are formed of waveform sipes having a smaller wavelength than the sipes 22 and 42 arranged in the inner vehicle mounting region Ai. As a result, the edge effect in the tire width direction WD is enhanced in the vehicle-mounted outer region Ao, which makes a large contribution during turning, while the edge effect in the tire circumferential direction CD is enhanced in the vehicle-mounted inner region Ai, which makes a large contribution during driving and braking. .

The ground contact half width HW is the distance in the tire width direction WD from the tire equator TE to the ground contact edge CE. The contact edge CE is the outermost part of the contact patch in the tire width direction WD when the tire PT is mounted on a regular rim, filled with the regular internal pressure, placed vertically on a flat road surface, and the regular load is applied. It's the location. The ground contact width CW is the width of the ground contact surface, and is the distance in the tire width direction WD between the pair of ground contact ends CE. Half of the ground contact width CW is the ground contact half width HW.

A regular rim is a rim defined for each tire by the standard in the standard system that includes the standard on which the tire is based, for example, a standard rim for JATMA, and a "Measuring Rim" for TRA and ETRTO. Regular internal pressure is the air pressure specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum air pressure, and for TRA it is the air pressure specified in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". ”, if it is ETRTO, it is “INFLATION PRESSURE”. Note that if the tire is for a passenger car, the pressure is 180 kPa, and if the tire is marked as Extra Load or Reinforced, the pressure is 220 kPa. The regular load is the load specified for each tire by each standard in the standard system including the standard on which the tire is based, and for JATMA it is the maximum load capacity, for TRA it is the maximum value listed in the table above, For ETRTO, it is "LOAD CAPACITY", but if the tire is for a passenger car, it is 88% of the corresponding load of internal pressure.

FIG. 2 is a plan view showing a single center block 1. FIG. In this tire PT, the width W1 of the center block 1 in the tire width direction WD is 55% or more of the ground contact half width HW, and the length L1 of the center block 1 in the tire circumferential direction CD is larger than the width W1. The width W1 is the length of the top surface of the center block 1 in the tire width direction WD from one end to the other end in the tire width direction WD . The length L1 is the length in the tire circumferential direction CD from one end of the top surface of the center block 1 in the tire circumferential direction CD to the other end. The center block 1 has a larger size in both the tire width direction WD and the tire circumferential direction CD than the center block included in a conventional tire.

The center block 1 is provided at the center of the tread surface Tr in the tire width direction WD , which has a high contribution to traction performance on an icy road surface. Since the center block 1 has a large size as described above, the ground contact area of the center block 1 increases, so the length and number of sipes 12 can be increased, and the edge component of the sipes 12 can be increased. In addition, if the center block 1 falls down greatly during the initial movement, it is difficult for the edge effect of the sipes 12 to be properly exerted. Excessive collapse can be suppressed. This improves traction performance on icy roads.

The width W1 is preferably 65% or less of the ground half width HW. That is, the width W1 is preferably 55 to 65% of the ground half width HW. This is because if the width W1 exceeds 65% of the ground contact half width HW, it becomes difficult to arrange the main grooves 62 and 63 necessary to ensure drainage performance. In order to effectively improve traction performance on an icy road surface, the length L1 is preferably 110% or more of the width W1. Further, the length L1 is preferably 200% or less of the width W1, more preferably 150% or less. When the length L1 exceeds 200% of the width W1, the number of lateral grooves 11 that partition the center block 1 decreases, which may reduce drainage performance.

In this embodiment, the width Wo as the tire width direction WD length from the vehicle-mounted outer end of the center block 1 to the tire equator TE is the tire width direction WD length from the vehicle-mounted inner end of the center block 1 to the tire equator TE. It is larger than the width Wi as a length. That is, the center block 1 is provided closer to the outer side of the vehicle with respect to the tire equator TE. In this way, by increasing the ground contact area of the center block 1 in the vehicle mounting outer region Ao (see FIG. 1), turning performance on an icy road surface can be improved. It is preferable that the width Wo is 50% or more of the ground half width HW. The width Wi is preferably 5 to 15% of the ground half width HW. The width Wo is preferably 80% or more of the width W1, more preferably 90% or more of the width W1.

A circumferential narrow groove 13 extending in the tire circumferential direction CD and a width direction narrow groove 14 extending in the tire width direction WD are formed in the center block 1. The circumferential narrow grooves 13 and the widthwise narrow grooves 14 are each formed to have a width of 3.0 mm or less and to be wider than the sipes 12. The circumferential narrow grooves 13 improve turning performance on snowy roads, and the widthwise narrow grooves 14 improve traction performance on snowy roads. The depths of these narrow grooves 13 and 14 are both smaller than the depth of the main grooves 62 and 63, for example, 50 to 85% of the depth of the main grooves 62 and 63. The depth of the lateral groove 11 is the same as the depth of the main grooves 62 and 63, but is not limited thereto.

The width W13 of the circumferential narrow groove 13 is, for example, 1.2 to 1.8 mm. The width W14 of the widthwise narrow groove 14 is, for example, 1.5 to 3.0 mm. The widths W13 and W14 are determined as the distance between a pair of parallel wall surfaces at locations where the narrow grooves 13 and 14 do not intersect. The widths W13 and W14 are smaller than the widths W62 and W63 (see FIG. 1) of the main grooves 62 and 63 that partition the center block row 10. The widths W61, W62, and W63 of the main grooves 61 to 63 are, for example, 4.5 to 13.5 mm. The width W11 of the lateral groove 11 is larger than the width W14 of the adjacent narrow groove 14 in the width direction, for example, 2.5 mm or more. The width dimensions of these grooves and sipes are measured when the tire is mounted on a regular rim, filled with the regular internal pressure, and under no load.

The circumferential narrow grooves 13 and the widthwise narrow grooves 14 are both formed outside the tire equator TE, without crossing the tire equator TE. Therefore, the narrow grooves 13 and 14 are not arranged in the vehicle-mounted inner region Ai (see FIG. 1), but are arranged only in the vehicle-mounted outer region Ao. This ensures rigidity near the tire equator TE of the center block 1, prevents excessive collapse at the time of initial movement, and improves traction performance on icy road surfaces.

In this embodiment, sipes 12 having different inclination directions are formed in a single center block 1. More specifically, the inclination directions of the sipes 12 are different between the outer side of the vehicle and the inner side of the vehicle with the circumferential narrow groove 13 as a boundary. Thereby, edge effects can be exerted in various directions.

In this embodiment, a single circumferential narrow groove 13 and two widthwise narrow grooves 14 extending from the midway point toward the outer side of the vehicle are formed in a single center block 1. However, there are no particular restrictions on the number or combination of these. Furthermore, although the circumferential narrow grooves 13 and the widthwise narrow grooves 14 both extend linearly, they are not limited to this, and may have bent or curved portions.

In this embodiment, since the circumferential narrow grooves 13 opened in the lateral groove 11 and the width direction narrow grooves 14 opened in the main groove 63 intersect with each other, the effect of improving traction performance and turning performance on snowy road surfaces is achieved. be enhanced. However, as in the modified examples of the center block 1 shown in FIGS. 3(A) to 3(F), the circumferential narrow groove 13 may close the lateral groove 11 without opening. Moreover, the width direction narrow groove 14 may be closed without opening into the main groove 63, and the circumferential direction narrow groove 13 and the width direction narrow groove 14 may not intersect with each other.

The pneumatic tire PT is characterized by the structure of the tread surface Tr as described above, and has excellent traction performance on icy road surfaces, so it is useful as a winter tire or an all-season tire. In the case of a winter tire, the rubber hardness of the tread rubber forming the tread surface Tr is, for example, 45 to 65°. This rubber hardness is the hardness measured at 23° C. according to JIS K6253 durometer hardness test (type A).

As described above, the pneumatic tire PT of the present embodiment includes the center block row 10 in which a plurality of center blocks 1 are arranged in the tire circumferential direction CD at the center of the tread surface Tr in the tire width direction WD. A plurality of sipes 12 are formed in the center block 1, the width W1 of the center block 1 in the tire width direction WD is 55% or more of the ground contact half width HW, and the length L1 of the center block 1 in the tire circumferential direction CD is It is larger than the width W1 of the center block 1.

The center portion of the tread surface Tr in the tire width direction WD tends to have a relatively high ground pressure on an icy road surface with a low coefficient of friction, making a large contribution to traction performance. In this tire PT, the center block row 10 provided at the center of the tread surface Tr in the tire width direction WD is composed of the large-sized center blocks 1 as described above. Therefore, the ground contact area of the center block 1 can be increased to increase the edge component of the sipes 12, and the rigidity of the center block 1 can be increased to suppress excessive collapse during initial movement. This improves traction performance on icy roads.

In the pneumatic tire PT of this embodiment, the length L1 of the center block 1 is 110% or more of the width W1 of the center block 1. This effectively improves traction performance on icy roads.

In the pneumatic tire PT of this embodiment, the mounting direction to the vehicle is specified, the center block row 10 is provided on the tire equator TE, and the width from the outer end of the center block 1 to the tire equator TE is Wo is larger than the width Wi from the inner end of the center block 1 to the tire equator TE. According to this configuration, turning performance on an icy road surface can be improved by increasing the ground contact area of the center block 1 in the vehicle mounting outer region Ao.

In the pneumatic tire PT of this embodiment, the distance Wo from the vehicle-mounted outer end of the center block 1 to the tire equator TE is 50% or more of the ground contact half width HW, and from the vehicle-mounted inner end of the center block 1 to the tire equator TE. The distance Wi is 5 to 15% of the ground contact half width HW. This effectively improves turning performance on icy roads.

In the pneumatic tire PT of the present embodiment, a circumferential narrow groove 13 extending in the tire circumferential direction CD and a widthwise narrow groove 14 extending in the tire width direction WD are formed in the center block 1. 13 and the widthwise narrow groove 14 are each formed to have a width of 3.0 mm or less and to be wider than the sipe 12. This improves traction performance and turning performance on snowy roads.

In the pneumatic tire PT of the present embodiment, the circumferential narrow grooves 13 and the widthwise narrow grooves 14 are both formed on the outer side of the tire equator TE, without crossing the tire equator TE. This ensures rigidity near the tire equator TE of the center block 1, prevents excessive collapse at the time of initial movement, and improves traction performance on icy road surfaces.

The pneumatic tire PT can be constructed in the same manner as a normal pneumatic tire, except that the tread surface Tr is constructed as described above, and any conventionally known material, shape, structure, manufacturing method, etc. can be employed. Although not shown, the pneumatic tire PT includes a pair of bead portions, a pair of sidewall portions extending outward in the tire radial direction from each of the bead portions, and an outer end of each of the pair of sidewall portions in the tire radial direction. The tread portion has a continuous tread portion, and the outer circumferential surface of the tread portion is formed by a tread surface Tr.

Although the embodiment of the present disclosure has been described based on the drawings, it should be understood that the specific configuration is not limited to this embodiment. The scope of the present disclosure is indicated not only by the description of the embodiments described above but also by the claims, and further includes all changes within the meaning and range equivalent to the claims.

The pneumatic tire of the present disclosure is not limited to the embodiments described above, nor is it limited to the effects described above. Various improvements and changes can be made to the pneumatic tire of the present disclosure without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1...Center block, 2...Shoulder block, 3...Shoulder block, 4...Quarter block, 10...Center block row, 11...Horizontal groove, 12...Sipe, 13... ... Circumferential narrow groove, 14... Width direction narrow groove, 20... Shoulder block row, 30... Shoulder block row, 40... Quarter block row, 61... Main groove, 62...・Main groove, 63... Main groove, TE... Tire equator, Tr... Tread surface , CD... Tire circumferential direction, WD... Tire width direction

Claims (5)

Equipped with a center block row in which multiple center blocks are lined up in the tire circumferential direction at the center of the tire width direction on the tread surface,
A plurality of sipes are formed in the center block,
The width of the center block in the tire width direction is 55% or more of the ground contact half width, and the length of the center block in the tire circumferential direction is greater than the width of the center block,
A circumferential narrow groove extending in the tire circumferential direction and a widthwise narrow groove extending in the tire width direction are formed in the center block,
The pneumatic tire is characterized in that the circumferential narrow groove and the widthwise narrow groove each have a width of 3.0 mm or less and are formed wider than the sipe . The pneumatic tire according to claim 1, wherein the length of the center block is 110% or more of the width of the center block. The mounting direction on the vehicle is specified,
The center block row is provided on the tire equator,
The pneumatic tire according to claim 1 or 2, wherein the width from the vehicle-mounted outer end of the center block to the tire equator is larger than the width from the vehicle-mounted inner end of the center block to the tire equator. The distance from the vehicle-mounted outer end of the center block to the tire equator is 50% or more of the ground contact half width, and the distance from the vehicle-mounted inner end of the center block to the tire equator is 5 to 15% of the ground contact half width. The pneumatic tire according to item 3. The pneumatic tire according to claim 1 , wherein the circumferential narrow grooves and the widthwise narrow grooves are both formed outside the tire equator when mounted on a vehicle, without crossing the tire equator.

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