JP5623717B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of ensuring both noise performance, steering performance, and wear performance on a paved road and securing traction in a muddy area.

  For tires attached to vehicles traveling in a muddy area, a method of improving lateral traction is taken for the purpose of ensuring the maneuverability when traveling in a muddy area. They mainly use an increase in the edge component in the tire width direction, and specifically, it is considered to add a groove (lug groove) or a sipe having an edge component in the tire axial direction.

JP 2001-30715 A Japanese Patent Application Laid-Open No. 6-299717 Japanese Utility Model Publication No. 1-147107

  However, the addition of grooves and sipes has the problem of reducing noise performance, maneuvering performance on paved roads, wear resistance, and the like. In addition, the addition of the groove will deteriorate the soil discharging performance in the muddy area.

  The present invention has been made to solve the above problems, and provides a pneumatic tire capable of ensuring both noise performance, steering performance, and wear performance on a paved road and securing traction in a muddy area. Is the purpose.

This invention is made | formed in view of the said fact, Comprising: The pneumatic tire of Claim 1 is a tire width rather than the ground contact edge of the lug groove arrange | positioned in the tread end side of the tread, and the said lug groove formed in a direction outwardly of the groove bottom, has a two gouging of circular arc cross sectional shape having an edge portion extending in a direction crossing the tire width direction, the tire width direction inner side of the 2 Tsunoeguri portion and R2 the radius of curvature of the gouge portion located, the radius of curvature of the gouge portion located outward in the tire width direction and R3, a 2mm ≦ R2 ≦ 10mm, 2mm ≦ R3 ≦ 10mm,.

Next, the operation of the pneumatic tire according to claim 1 will be described.
The pneumatic tire according to claim 1, of the lug grooves, in contact with are two gouging of arcuate cross-section in the tire width direction outer side of the groove bottom than the ground end formation, gouging of the edge road Therefore, during general traveling on a paved road, the edge of the bore does not affect noise and wear.

On the other hand, when traveling on muddy ground, the soil that has entered the lug groove is caught by the edge extending in the direction intersecting the tire width direction at the groove bottom, and the traction in the tire width direction is improved, thereby improving the steering performance.
In addition, the formation of the corrugation increases the surface area of the groove bottom, increases the contact surface with the soil that enters the lug groove when traveling on muddy ground, and leads to improved traction.

  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the lug groove is formed in the shoulder block so as not to penetrate a shoulder block formed on a tread end side of the tread, The lug groove is formed shallower than the groove disposed around the shoulder block.

Next, the operation of the pneumatic tire according to claim 2 will be described.
The lug groove is formed in the shoulder block so as not to penetrate the shoulder block, and is formed shallower than the groove disposed around the shoulder block, so that a decrease in rigidity of the shoulder block is suppressed.

  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it is possible to ensure both noise performance, steering performance, and wear performance on the paved road and traction on the muddy ground. It has the excellent effect of being able to.

  Since the pneumatic tire according to claim 2 has the above-described configuration, a decrease in rigidity of the shoulder block can be suppressed. Thereby, the influence on steering stability, abrasion resistance, etc. is suppressed.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. It is a perspective view which shows the shoulder side of a tread. It is sectional drawing (3-3 sectional view of FIG. 1) along the tire rotating shaft of the shoulder block of embodiment. It is sectional drawing along the tire rotating shaft of the shoulder block in the pneumatic tire of a prior art example.

A pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1-3, the circumferential direction main groove 14 extended along a tire circumferential direction is formed in the tread 12 of the pneumatic tire 10 of this embodiment on both sides of the tire equatorial plane CL.
The first lug groove 16 and the second lug groove 18 extending from the circumferential main groove 14 to the outside of the ground contact end 12A are alternately arranged in the tire circumferential direction on the land portion on the outer side in the tire width direction from the circumferential main groove 14 of the tread 12. Is formed.

  The ground contact edge 12A attaches the pneumatic tire 10 to a standard rim defined in JATMA YEAR BOOK (Japan Automobile Tire Association Standard, 2009 edition), and the maximum load capacity in the applicable size / ply rating in JATMA YEAR BOOK ( This is when the maximum load capacity is loaded with an internal pressure of 100% of the air pressure (maximum air pressure) corresponding to the internal pressure-load capacity correspondence table (bold load). When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

In the tread 12, a portion surrounded by the circumferential main groove 14, the first lug groove 16, and the second lug groove 18 is a shoulder block 20.
Note that, in the region on the outer side in the tire width direction from the ground contact end 12A of the tread 12, that is, in the shoulder portion, the first lug groove 16 has a portion 16A extending substantially in the tire width direction and a portion 16B inclined with respect to the tire width direction. It is branched to. Moreover, the 2nd lug groove 18 inclines with respect to the tire width direction in the shoulder part.

The shoulder block 20 is formed with a third lug groove 22 having a groove depth shallower than that of the circumferential main groove 14, the first lug groove 16, and the second lug groove 18.
The end of the third lug groove 22 on the tire equatorial plane CL side terminates in the block, and the end on the outer side in the tire width direction extends outward in the tire width direction from the ground contact end 12A of the tread 12. In addition, it connects to the edge part by the side of the shoulder part of the 3rd lug groove 22 connected to the intermediate part of the part 16B which inclines with respect to the tire width direction of the 1st lug groove 16, and the 2nd lug groove 18. There is a third lug groove 22.

  In the third lug groove 22, two counterbores 24 are formed on the groove bottom on the outer side in the tire width direction than the ground contact end 12 </ b> A. As shown in FIG. 3, the bore portion 24 of the present embodiment has an arc shape when viewed in a cross section along the tire rotation axis, and an edge 24 </ b> A is formed at the edge of the bore portion 24. Yes.

  In the shoulder block 20 of the present embodiment, a sipe 26 extending in the tire width direction connecting the third lug groove 22 and the circumferential main groove 14 is formed. The sipe 26 has a groove width that is closed when the shoulder block 20 is grounded (the wall surfaces facing each other are in contact with each other).

  As shown in FIG. 1, the land portion between the pair of circumferential main grooves 14 has an inverted S-shaped first inclined groove 28 on the tire equatorial plane CL, and the tire equatorial plane CL side from the circumferential main groove 14. A second inclined groove 30 extending in a circular arc shape toward the arc, a third inclined groove 32 connecting the end of the first inclined groove 28 and the end of the second inclined groove 30, and one side of the tire equatorial plane CL. A fourth inclined groove 34 connecting the end of the second inclined groove 30 and the end of the second inclined groove 30 on the other side, and a short fourth lug groove 36 extending from the circumferential main groove 14 toward the tire equatorial plane CL. A sub-groove 38 that connects the end of the fourth lug groove 36 and the end of the first inclined groove 28, and a circumferential groove that connects the intermediate portion of the first inclined groove 28 and the intermediate portion of the second inclined groove 30. 40 is formed, and a center block 42 is defined on the tire equatorial plane CL by these grooves. The tire width direction on both sides of the click 42, the first second block 44, and a second second blocks 46 are partitioned.

  A sipe 48 is formed in the center block 42, a sipe 50 is formed in the first second block 44, and a sipe 52 is formed in the second second block 46.

(Action)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
First, during general traveling on a paved road, in the pneumatic tire 10 of the present embodiment, a hollow portion 24 is formed on the groove bottom of the third lug groove 22 of the shoulder block 20 on the outer side in the tire width direction from the ground contact end 12A. Therefore, the edge 24A of the bore portion 24 does not contact the road surface, so the edge 24A of the bore portion 24 does not affect noise and wear of the shoulder block 20.

On the other hand, when traveling on muddy ground, the soil that has entered the groove of the third lug groove 22 is caught by the edge 24A of the bore portion 24 and the traction in the tire width direction is improved, so that the steering performance is improved. Furthermore, the surface area of the groove bottom is increased by forming the hollow portion 24 at the groove bottom on the outer side in the tire width direction from the ground contact end 12A of the third lug groove 22, so that the inside of the third lug groove 22 is in a muddy ground. The contact surface with the invading soil increases and traction improves.

In the present embodiment, the third lug groove 22 does not penetrate the shoulder block 20, and the circumferential main groove 14, the first lug groove 16, and the third lug groove 22 define the shoulder block 20, And since it is formed shallower than the 2nd lug groove 18, the rigidity fall of the shoulder block 20 is suppressed, and the rigidity of the shoulder block 20 is fully ensured.
In the present embodiment, since the shape of the bore portion 24 is an arc shape as described above, a portion where stress is easily concentrated on the groove bottom is not formed, and generation of cracks from the groove bottom is suppressed.

(Other embodiments)
The number of the punching portions 24 formed on the groove bottom of the third lug groove 22 is two in the above embodiment, but may be three or more.
In the above embodiment, the cross-sectional shape of the bore portion 24 is an arc shape, but may be another shape.

(Test example)
In order to confirm the effect of the present invention, the tire of the comparative example and the tire of the example to which the present invention was applied were prepared and mounted on an actual vehicle, and the steering performance in a muddy place was compared.
Example tire: The pneumatic tire described in the above embodiment.
Tire of comparative example: tire of the example in which no punched portion is formed (see FIG. 4).

Shape dimensions (see Figure 3)
Groove depth of first lug groove 16 and second lug groove 18: SD (unit: mm)
Groove depth of the third lug groove 22: a (unit: mm)
Groove depth of the third lug groove 22 at the shoulder portion: b (unit: mm)
Curvature radius: R1 (unit: mm)
Curvature radius: R2 (unit: mm)
Curvature radius: R3 (unit: mm)
0.2 × SD ≦ a ≦ 0.6 × SD , 1.0 ≦ b ≦ 3.0, 10 ≦ R1 ≦ 30, 2 ≦
R2 ≦ 10, 2 ≦ R3 ≦ 10

Field test outline Vehicle: Toyota Land Cruiser Tire size: PSR275 / 70R60 114S
Air pressure: 3.5 MPa before / after
Total vehicle weight: 3200kg

  The test driver evaluated the steering performance in a muddy area. The evaluation is an index display with the comparative example being 100, and the larger the value, the better the steering performance in the muddy area.

試験結果が示す様に、本発明の適用された実施例のタイヤは、泥濘地での操舵性能が向上していることが分かる。

As the test results show, it can be seen that the tire of the example to which the present invention is applied has improved steering performance in a muddy area.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Circumferential main groove 16 1st lug groove 18 2nd lug groove 20 Shoulder block 22 3rd lug groove 24A Edge 24 Overhanging part R2 Curvature radius R3 Curvature radius

Claims (2)

Lug grooves arranged on the tread end side of the tread;
Of the lug grooves, it is formed in the tire width direction outer side of the groove bottom than the ground terminal, and an arc-shaped cross section of the two gouging portion having an edge portion extending in a direction crossing the tire width direction,
Have
When the radius of curvature of the bore portion located on the inner side in the tire width direction is R2 and the radius of curvature of the bore portion located on the outer side in the tire width direction is R3 ,
2 mm ≦ R2 ≦ 10 mm,
2 mm ≦ R3 ≦ 10 mm,
Is a pneumatic tire. The lug groove is formed in the shoulder block so as not to penetrate the shoulder block formed on the tread end side of the tread,
The pneumatic tire according to claim 1, wherein the lug groove is formed shallower than a groove disposed around the shoulder block.

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