JP2003011619A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire of a rib pattern capable of compatibly securing wet performance, reduction in rolling resistance, and eccentric abrasion. SOLUTION: Sipes 24 extending in the tire width direction are formed in respective ribs so as to improve the wet performance. The sipe 24 is so formed that its opening side is made to incline on the opposite side to the tire rotation direction (arrow A direction) relative to the tire radial direction (arrow B direction) so that the rigidity on the treating side of a land part 25 divided by the sipe 24 is made high, while the rigidity on the kicking side is made low, which can suppress the heel-and-toe abrasion. A cutout 26 is formed in the treading end in the land part 25 so as to delay the landing of the treading end, suppress deformation caused by a sliding contact, and reduce the rolling resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a rib pattern, and more particularly to a pneumatic tire having ribs provided with sipes.

[0002]

2. Description of the Related Art In pneumatic tires having a rib pattern, it is well known that sipes are frequently used for ribs in order to ensure wet performance.

However, when the sipe is adopted, the wet performance is improved, but the wear of the kick-out end of the block delimited by the sipe progresses more than the wear of the step-in end.
So-called heel-and-to uneven wear occurs, and the performance is often impaired in terms of uneven wear.

As one of the techniques for providing the sipes and ensuring the uneven wear resistance while ensuring the wet performance, the sipes are tilted in the direction opposite to the tire rotation direction with respect to the tire radial direction so that the sipes are partitioned. There is a technique for improving the uneven wear resistance by changing the balance between the land side rigidity on the stepping side and the land side rigidity on the kicking side.

[0005]

Generally, when the pneumatic tire rolls under load and the tread comes into contact with the road surface, the belt undergoes a change in the cord angle at the stepping portion. As a result, relative displacement in the tire width direction occurs between the tread surface and the belt (that is, the tread rubber), and the stepped end of the land portion comes into contact with the road surface while sliding in the tire width direction. There is a problem that the deformation of the land portion becomes large and the rolling resistance increases.

Here, when the sipe formed on the rib is inclined toward the step-in side, the rigidity of the step-in side of the block becomes high, so that the ground contact pressure rises and the belt at the time of stepping at the step-in end where the ground contact pressure rises The work of wear caused by slippage due to the difference in the diameter of the steel sheet increases.

As a result, the tire in which the sipe formed on the rib is inclined toward the step-in side becomes a tire having a high rolling resistance.

In consideration of the above facts, an object of the present invention is to provide a pneumatic tire having a rib pattern capable of achieving both wet performance, reduction of rolling resistance and uneven wear.

[0009]

According to a first aspect of the present invention, the crown portion of the radial carcass is provided with a belt including a plurality of cords that are inclined with respect to the tire circumferential direction, and the belt is radially outside of the belt. The tread is a pneumatic tire having a plurality of ribs divided by a plurality of circumferential main grooves extending in the circumferential direction, the pneumatic tire extending in the tire width direction and opening in the tire radial direction. The side is inclined so as to be opposite to the tire rotation direction, and has a plurality of sipes partitioning the rib into a plurality of land portions, and a notch formed at a stepping side end of the land portion, There is.

Next, the operation of the pneumatic tire according to claim 1 will be described.

In the pneumatic tire of the first aspect, since the sipes extending along the tire width direction are formed on the ribs, the wet performance is improved.

Further, since the sipes are inclined with respect to the tire radial direction so that the opening side is opposite to the tire rotation direction, the rigidity of the land portion on the stepping side of the land portion partitioned by the sipes is high, and the kicking The rigidity of the land on the side is reduced, and the heel
And-to wear can be suppressed.

When the pneumatic tire rolls under load and the tread comes into contact with the road surface, the belt causes a change in the angle of the cord at the stepped portion, so that a relative displacement in the tire width direction occurs between the tread surface and the belt. The stepped end of the land part slides in the tire width direction and contacts the road surface.

However, by providing the notch at the stepping end of the land portion separated by sipes, the grounding of the stepping end can be delayed, deformation due to sliding contact is suppressed, and rolling resistance is reduced.

The sipes may be parallel to the tire width direction or may be inclined.

The invention according to claim 2 is characterized in that, in the pneumatic tire according to claim 1, the inclination angle of the sipe with respect to the tire radial direction is set within a range of 3 to 15 °.

Next, the operation of the pneumatic tire according to claim 2 will be described.

If the angle of inclination of the sipe is less than 3 °, the effect of suppressing heel-and-toe wear becomes small.

On the other hand, when the inclination angle of the sipe exceeds 15 °, the rigidity of the land portion on the kicking side becomes too low and the rigidity of the land portion on the stepping side becomes too high, and rolling resistance increases.

According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the depth of the notch is 10 to 60% of the depth of the sipe. I am trying.

Next, the operation of the pneumatic tire according to claim 3 will be described.

If the depth of the notch is less than 10% of the depth of the sipe, the notch disappears in the initial stage of wear and rolling resistance increases during the middle stage of wear.

In the latter stage of wear, the distance between the tread surface and the belt becomes short and the relative displacement in the tire width direction between the tread surface and the belt becomes small, so the rolling resistance is small.

On the other hand, the depth of the notch is 60 times the depth of the sipe.
If it exceeds%, the deformation of the land block divided into sipes by stepping in and kicking out will increase, the amount of wear work will increase, and heel and toe wear will be promoted.

The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3.
The width of the notch is 5 to 50 of the circumferential pitch dimension of the sipe.
It is characterized by being%.

Next, the operation of the pneumatic tire according to claim 4 will be described.

If the width of the notch is less than 5% of the circumferential pitch of the sipe, it is impossible to delay the grounding of the stepped end, and it is impossible to suppress the deformation due to the sliding contact and to reduce the rolling resistance.

On the other hand, if the width of the notch exceeds 50% of the circumferential pitch of the sipe, the deformation of the land block becomes large and the land volume is increased, as in the case of the operation of claim 4. Becomes smaller, which adversely affects the wear life.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the pneumatic tire of the present invention will be described with reference to FIGS.

In FIG. 1, arrow L direction and arrow R
The direction indicates the tire width direction, and the arrow S direction indicates the tire circumferential direction.

As shown in FIG. 1, in the tread 12 of the pneumatic tire 10 of this embodiment, the tire circumferential direction (arrow) is provided on both sides in the tire width direction (arrow L direction and arrow R direction) across the tire equatorial plane CL. A circumferential main groove 14 linearly extending along the S direction) is formed, and a circumferential main groove 16 linearly extending along the tire circumferential direction is formed outside the circumferential main groove 14 in the tire width direction. Has been done.

Since the pneumatic tire 10 is a so-called steel radial tire in which a steel belt including a plurality of steel cords inclined with respect to the tire equatorial plane is arranged in the crown portion of the radial carcass, the internal structure will not be described. Omit it.

The tread 12 has two circumferential main grooves 14
A center rib 18 sandwiched between the two main ribs, a second rib 20 sandwiched between the circumferential main groove 14 and the circumferential main groove 16, and a shoulder rib 22 arranged outside the circumferential main groove 16 in the tire width direction are formed. A plurality of sipes 24 extending in the tire width direction are formed in the tire circumferential direction.

The circumferential pitch P of sipes in one rib (measured along the outer circumference on the tread) is 25 to 50.
The range of mm is preferable.

As shown in FIG. 2, the sipe 24 is inclined at an angle θ1 in the direction opposite to the tire rotation direction (arrow A direction) with respect to the tire radial direction (arrow B direction).

The angle θ1 of the sipe 24 is preferably in the range of 3 to 15 °.

The width W1 of the sipe 24 is preferably 2.5 mm or less.

The direction of inclination of the sipe 24 with respect to the tire width direction may be rightward or leftward.

As shown in FIG. 2, sipe 24 and sipe 2
A notch 26 having a rectangular cross section is formed at the stepped end of the block-shaped land portion 25 formed between the land portion 4 and the land 4.

The depth d of the notch 26 is the depth D of the sipe 24.
The range of 10 to 60% is preferable.

The width e of the notch 26 (measured along the outer circumference on the tread surface) is preferably within the range of 5 to 50% of the circumferential pitch P of the sipes 24.

The pneumatic tire 10 of this embodiment has a tread width W of 205 mm and a center rib 18 width of 27 mm.
The width of the second rib 20 is 27 mm and the width of the shoulder rib 22 is 38 mm.

The sipe 24 has a depth D of 13 mm and a pitch P.
Is 35 mm and the width W1 is 1.0 mm.

The notch 26 has a width e of 7 mm and a depth d of 4 mm.

By the way, in this embodiment, the depth d of the notch 26 is 31% of the depth D of the sipe 24 and the width e of the notch 26.
Is 20% of the circumferential pitch P of the sipes 24. (Operation) In the pneumatic tire 10 of the present embodiment, since the sipe 24 extending in the tire width direction is formed in each rib, the wet performance is improved.

Since the sipe 24 is inclined with respect to the tire radial direction on the side opposite to the tire rotation direction, the rigidity of the landing portion 25 partitioned by the sipe 24 is high on the stepping side and low on the kicking side. , Heel and toe wear can be suppressed.

Since the notch 26 is provided at the stepping end of the land portion 25, the grounding of the stepping end can be delayed, deformation due to sliding contact can be suppressed, and rolling resistance can be reduced. Therefore, the fuel efficiency performance is improved.

If the inclination angle θ1 of the sipe 24 is less than 3 °, the effect of suppressing heel-and-toe wear becomes small, and the inclination angle θ1 of the sipe 24 is 15 °.
If it exceeds, rolling resistance will increase.

When the circumferential pitch P of the sipes 24 is less than 25 mm, the rigidity of the land block divided by the sipes 24 becomes small, which promotes heel-and-toe wear.

On the other hand, the circumferential pitch P of the sipes 24 is 50.
If it exceeds mm, the wet performance cannot be improved.

The depth d of the notch 26 is the depth D of the sipe 24.
If it is less than 10%, the notch 26 disappears in the initial stage of wear, and the rolling resistance increases in the middle stage of wear.

On the other hand, when the depth d of the notch 26 exceeds 60% of the depth D of the sipe 24, the deformation of the land block divided by the sipe 24 by stepping in and kicking out becomes large, and the wear work amount becomes large. Increase and promote heel and toe wear.

If the width e of the notch 26 is less than 5% of the circumferential pitch P of the sipes 24, the rolling resistance cannot be reduced.

On the other hand, when the width e of the notch 26 exceeds 50% of the circumferential pitch P of the sipes 24, the deformation of the land block becomes large and the land volume becomes small, so that the wear life becomes longer. It will also have an adverse effect.

Although the notch 26 has a rectangular cross-sectional shape in the above embodiment, the present invention is not limited to this, and the C-chamfered shape as shown in FIG. 3 and the arc inside the tire as shown in FIG. A convex arc shape having a center, a concave arc shape having an arc center on the outside of the tire as shown in FIG. 5, a concave arc shape having an end of the concave arc shape as shown in FIG. May be

Further, in the above embodiment, the sipe 24 has a linear shape, but the present invention is not limited to this, and may be bent in the middle as shown in FIG. 7, and curved as shown in FIG. You can do it. (Test Example) In order to confirm the effect of the present invention, Table 1 below.
The tire of the conventional example, the tire of the comparative example, and the tire of the example to which the present invention is applied are prepared, and the uneven wear test and the rolling resistance test are performed.

The tire pattern used was that shown in FIG.

Uneven wear test: high-speed route truck (2DD)
Test tire (TBR11R22.5 1
4PR. With an internal pressure of 800 kpa), 10,000 km
The uneven wear amount difference in heel and toe wear after running (difference in land height between the most worn part and the most remaining part) was measured.

The evaluation is based on the difference in the uneven wear amount of the conventional tire as 1.
It is represented by an index of 00, and the smaller the value, the better the uneven wear resistance.

Rolling resistance test: TBR11R22.5
A test tire of 14PR was tested with an internal pressure of 800 kpa and a load of 27.
The measurement was performed under the conditions of 00 kgf and a speed of 80 km / h.

The evaluation was carried out by using the rolling resistance of the conventional tire as 1
It is represented by an index of 00, and the smaller the value, the smaller the rolling resistance.

[0062]

[Table 1]

The sipe inclination angle of "-3 degrees" means that the sipe is inclined such that the opening side is in the same direction as the rotation direction with respect to the tire radial direction.

[0064]

As described above, since the pneumatic tire of the present invention has the above-mentioned structure, it is possible to achieve both wet performance, reduction of rolling resistance and uneven wear in a tire having a rib pattern. Has excellent effect.

[Brief description of drawings]

FIG. 1 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a perspective view of ribs of the tread of the pneumatic tire according to the embodiment of the present invention.

FIG. 3 is a side view of a rib showing another embodiment of the cutout.

FIG. 4 is a side view of a rib showing a further embodiment of the notch.

FIG. 5 is a side view of a rib showing still another embodiment of the notch.

FIG. 6 is a side view of a rib showing still another embodiment of the cutout.

FIG. 7 is a plan view of a tread of a pneumatic tire according to another embodiment of the present invention.

FIG. 8 is a plan view of a tread of a pneumatic tire according to still another embodiment of the present invention.

[Explanation of symbols]

10 pneumatic tires 12 treads 14 circumferential main groove 16 circumferential main groove 18 Center rib 20 second rib 22 Shoulder rib 24 Sipe 26 notches

Claims (4)

[Claims] 1. A crown portion of a radial carcass is provided with a belt including a plurality of cords inclined with respect to a tire circumferential direction, and a tread on a tire radial direction outer side of the belt has a plurality of circumferentially extending tires. A pneumatic tire formed with a plurality of ribs divided by a circumferential main groove, extending along the tire width direction and inclined such that the opening side is opposite to the tire rotation direction with respect to the tire radial direction. A pneumatic tire comprising: a plurality of sipes partitioning the rib into a plurality of land portions; and a notch formed at a stepping side end of the land portion. 2. The pneumatic tire according to claim 1, wherein an inclination angle of the sipe with respect to a tire radial direction is set within a range of 3 to 15 °. 3. The pneumatic tire according to claim 1 or 2, wherein the depth of the notch is 10 to 60% of the depth of the sipe. 4. The pneumatic container according to claim 1, wherein the width of the notch is 5 to 50% of a circumferential pitch dimension of the sipe. tire.