JPH1178429A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of heel-and-toe wear and improve on noise caused by the hammering sound of a block by forming the tread of a step-in side edge part of the block into a circular arc face, and arranging a sipe for separating the block 4 into a block body and a kick-out side small block part, in an inclined state at a kick-out side edge part. SOLUTION: The tread 5a of a step-in side edge part 5 of a block 4 is formed in an outward protruded circular arc face lowered inward in the radial direction of a tire toward the edge E1 side, and a kick-out side edge part 6 is provided with a sipe 7 separating the block 4 into a block body 4A and a kick-out side small block part 4B along a lateral groove 3. The sipe 7 is arranged inclining onto the block body 4A side toward the bottom side. Ground pressure, when the edge part 5 grounds on the road surface, can therefore be reduced, and noise caused by hammering sound in the initial period of wear of the tire can be reduced. The slip of the small block part 4B is made large, so that wear energy is concentrated so as to suppress heel-and-toe wear.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire provided with a block pattern, which suppresses the occurrence of heel-and-toe wear and improves the noise caused by the striking sound of the block. Related to pneumatic tires.

[0002]

2. Description of the Related Art In general, a pneumatic tire having a block pattern provided on a tread surface has a higher running noise than a rib pattern or the like. The main type of the noise is the hitting of the road surface by a block. This occurs when the stepping side of the block hits the road surface. Also, in the block pattern, the kick-out side of the block slides greatly, so that heel-and-toe wear occurs in which a difference in wear occurs between the kick-out side and the step-in side. Time)
There is a problem that noise is further promoted by the uneven wear.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire provided with a block pattern, which suppresses the occurrence of heel-and-toe wear in the initial stage of tire wear and improves the noise due to block hitting noise. It is to provide a pneumatic tire which can be used.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a main groove extending in a tire circumferential direction on a tread surface in which a tire rotation direction is designated in one direction, and a lateral groove extending in a tire width direction is formed in a tire circumferential direction. In a pneumatic tire in which a plurality of blocks are formed by being arranged at a predetermined pitch in the direction and being divided by the main groove and the lateral groove, an arc in which the stepped side edge portion tread surface of the block is set inward in the tire radial direction toward the edge side. A sipe formed on the surface and separating the block into a block main body and a kick-out side small block along the lateral groove at the kick-out side edge is disposed so as to be inclined such that the bottom side is on the block main body side. It is characterized by having done.

Since the tread surface on the tread-side edge is formed into an arc surface, the contact pressure when the tread on the edge touches the road surface can be reduced. can do. In addition, a sipe is formed along the lateral groove at the edge on the kicking side, and the block is separated into the block body and the small block on the kicking side. As a result, propagation propagation to the block body can be suppressed. Therefore, heel-and-toe wear of the block body acting as an actual block can be suppressed. On the other hand, by arranging the sipe so as to be inclined as described above, the kick-out side of the block body can be easily released to the adjacent lateral groove side during rotation, so that the ground pressure at the kick-out side is reduced. The heel and toe wear of the block body can be further reduced. Accordingly, it is possible to suppress the noise from being promoted due to the uneven wear in the early stage of the tire wear.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a tread pattern of the pneumatic tire of the present invention. A main groove 2 extending straight along a tire circumferential direction T is provided on a tread surface 1 in which a tire rotation direction R is specified in one direction.
Between the main grooves 2, lateral grooves 3 extending straight in the tire width direction are arranged at a predetermined pitch in the tire circumferential direction T, and the main grooves 2 and the lateral grooves 3 connect the blocks of the adjacent block rows in the tire circumferential direction. A large number of blocks 4 are formed so as to be shifted.

As shown in FIG. 2, each block 4 is formed in an arcuate surface in which the tread surface 5a of the stepping-side edge portion 5 becomes lower toward the edge E1 side inward in the tire radial direction and becomes convex outward. A single sipe 7 extending straight along the lateral groove 3 is provided at the kick-out side edge 6 at both ends of the main groove 2.
The block 4 is formed by a sipe 7 extending to the vicinity of the bottom of the main groove 2 so as to communicate with the block main body 4A.
And the kick-out side small block portion 4b. The sipe 7 is arranged so as to be inclined so that the bottom side is closer to the block body 4A.

The wall surface 5b of the stepped edge portion 5 facing the lateral groove 3 is formed as an inclined surface such that the width of the lateral groove 3 becomes wider toward the opening side. The wall surface 6b facing 3 is formed on an inclined surface such that the width of the lateral groove 3 becomes narrower toward the opening side, and is inclined in the same direction as the sipe 7. As described above, according to the present invention, since the stepped side edge portion tread surface 5a which greatly affects the hitting sound of the block is formed into an arc surface, the contact pressure when the edge portion 5 contacts the road surface can be reduced. It is possible to reduce the noise due to the tapping sound at the beginning of tire wear.

A sipe 7 is provided along the lateral groove 3 at the kick-out side edge portion 6 to separate the block 4 into a block main body 4A and a small block portion 4B on the kick-out side. The block main body 4A which acts as an actual block by increasing the slip and concentrating the wear energy, suppressing propagation to the block main body 4A.
Heel and toe abrasion can be suppressed, while the sipe 7 is inclined such that the bottom side thereof is on the block body 4A side, so that the kick-out side of the block body 4A during driving can easily escape to the adjacent lateral groove side. Since the contact pressure can be reduced, the heel and toe wear of the block body 4A can be further suppressed. as a result,
The promotion of noise due to the uneven wear is suppressed, and
It is possible to further reduce noise at the initial stage of wear when traveling 10,000 km.

FIG. 3 shows an example of another block of the pneumatic tire of the present invention. In this embodiment, the wall surface 6b of the kick-out side edge portion 6 facing the lateral groove 3 is formed on an inclined surface such that the width of the lateral groove 3 becomes wider toward the opening side, and the edge portion 6 is formed in the same manner as described above. This is provided with an inclined sipe 7. The wall surface 6b and the sipe 7 have a C-shape when the tread surface faces upward. It is preferable to incline the wall surface 6b of the kick-out side edge portion 6 in the same direction as the sipe 7, as in the above-described embodiment, since the function of the small block portion 4B can be more effectively exhibited. The block may be configured as shown in FIG.

[0011] In the present invention, about 1.0~3.0mm as the tire circumferential direction length L ₅ of the arc surface which is formed on the leading side edge portions tread 5a, substantially as sagging amount d of the edge E1 0. It can be about 5 to 1.5 mm. As the tire circumferential direction length L ₆ of the tread from the edge E2 of the trailing side edge portion 6 to sipes 7, it may be in the range of about approximately 1.5 to 4.5 mm.

In the present invention, as described above, each block 4
Is preferably configured as shown in FIGS. 2 and 3. However, 90% or more of all blocks may be formed in the above-described blocks. Further, in the above embodiment, the block main body 4A and the small block portion 4B are completely separated from the beginning by the sipe 7, but the sipe 7 connects the block main body 4A and the small block portion 4B with the thin rubber portion. 7
The present invention also includes a configuration in which the thin rubber portion is cut off during traveling so that the block 4 is separated into the block main body 4A and the small block portion 4B.

The present invention particularly relates to JATMA (JATMA YEAR B
OOK 1997) can be preferably used for pneumatic tires for passenger cars.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The tire size is made common to 205 / 60R15, and in the block pattern of FIG. 1, the tread surface on the stepping side edge of each block is formed into an arc surface, and a sipe is provided at the kicking side edge portion to block the block. A tire of the present invention having the block shown in FIG. 2 separated into a main body and a small block portion on a kick-out side, and a conventional tire of the present invention having no arc surface and no sipe were produced.

Each of these test tires was rim size 15 × 6.
Attach it to the JJ rim and set the air pressure to 200 kPa to 300
When mounted on a 0 cc vehicle and evaluated for noise performance and heel and toe wear under the following measurement conditions, the results shown in Table 1 were obtained. Heel and toe wear After traveling 10,000 km on a general road, measure the step difference between the kicking side and the stepping side edge of each block body in the same one block row of each test tire mounted on the front wheel, and measure it for one block. The average was converted per hit. The smaller the value is, the smaller the heel and toe wear amount is, and the more excellent it is. Noise performance After measuring the heel and toe abrasion amount, the noise due to the hitting sound of the block when traveling straight at 80 km / h on the drum in the indoor anechoic chamber was measured, and the evaluation was made based on the conventional tire (0). . The larger the value of-, the better the noise performance.

[0016]

[Table 1] As is clear from Table 1, it can be seen that the present invention can improve the noise caused by the striking sound of the block while suppressing the occurrence of heel and toe wear in the early stage of tire wear.

[0017]

As described above, according to the present invention, in a pneumatic tire provided with a block pattern, the tread surface on the stepping side edge portion of the block is formed in an arcuate surface that is radially inward toward the tire side toward the edge side, and is kicked. The sipe that separates the block into the block main body and the kick-out small block along the lateral groove is arranged at the exit side edge so that the bottom side is inclined to the block body side. It is possible to reduce the noise due to the tapping sound of the block while suppressing the occurrence of wear.

[Brief description of the drawings]

FIG. 1 is a development view of a principal part of a tread showing an example of a pneumatic tire of the present invention.

FIG. 2 is an enlarged sectional view taken on line AA of FIG. 1;

FIG. 3 is an enlarged sectional view showing another example of the block in FIG. 1;

[Explanation of symbols]

Reference Signs List 1 tread surface 2 main groove 3 lateral groove 4 block 4A block main body 4B kick-out side small block portion 5 step-in side edge portion 5a tread surface 6 kick-out side edge portion 6b wall surface 7 sipes E1, E2 edge R Tire rotation direction T tire circumferential direction

Claims (2)

[Claims] 1. A main groove extending in a tire circumferential direction is provided on a tread surface in which a tire rotation direction is specified in one direction, and lateral grooves extending in a tire width direction are arranged at a predetermined pitch in a tire circumferential direction. In a pneumatic tire formed with a number of blocks partitioned by lateral grooves, the stepped-side edge portion tread surface of the block is formed in an arcuate surface inwardly in the tire radial direction toward the edge side, and the kick-out side edge portion is A pneumatic tire in which a sipe that separates the block into a block main body and a kick-out side small block portion along a lateral groove is inclined so that a bottom side thereof is on the block main body side. 2. The pneumatic tire according to claim 1, wherein a wall surface facing a lateral groove of the kick-out side edge portion is inclined in the same direction as the sipe.