JP2001206018A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve traction performance by a plurality of blocks and sipes formed of circumferential grooves and lateral grooves, while holding the rigidity of the blocks. SOLUTION: Where there are three or more odd number of circumferential grooves 103, two rows of the blocks 112 across a circumferential groove 106 positioned in the tire center are set to symmetric as a same phase, and where there are an even number of the circumferential grooves, the pitch in the middle- side two circumferential grooves 106 is set larger (approximately double) than the pitches between other circumferential grooves. Two rows of blocks 112 are formed in the approximately doubled width pitch and set to symmetric as the same phase. This constitution can approximately double a traction obtained by the two blocks at all times, irrelevant to an empty vehicle or a vehicle loaded with a prescribed load. This pneumatic tire is prevented from reducing a unit surface area of the block which causes the reduction in the rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the present invention, in which at least three circumferential grooves are provided along the circumferential direction of a tread, and lateral grooves are provided so as to intersect the circumferential grooves. The present invention relates to a studless specification pneumatic tire in which blocks divided by lateral grooves are formed, and a sipe is formed for each block.

[0002]

2. Description of the Related Art Conventional studless pneumatic tires, particularly pneumatic tires for heavy loads, have grooves (circumferential grooves) formed in a tread portion along a circumferential direction. A transverse groove is provided so as to be orthogonal to the circumferential groove, and a plurality of blocks divided by the circumferential groove and the transverse groove are formed.

In the above-mentioned conventional studless tires, adjacent block rows are generally arranged alternately (1/2 phase difference) (for example, as an example).
See JP-A-10-86610).

Further, a sipe is formed in each block, and a lug groove is formed in a shoulder portion of the block and the tread. As a result, traction is improved as compared with a normal tire.

[0005] The sipe absorbs dissolved water which causes a water film formed between the road surface and the tire by absorbing the water film, and the traction is achieved by cutting the water film on the road surface by the edge portion and securely contacting the road surface. It has the role of further improving the performance and improving the running stability on snow.

Here, the number of blocks and the number of sipes are
It has been found that it has a great effect on traction control on snow, and in order to improve traction on ice (including snow-covered roads), which is more severe than on snow, block segmentation (unit block surface) Area) and the sipes need to be increased.

However, the segmentation of the block and the increase in sipes cause a decrease in rigidity of the block itself, leading to a decrease in block durability.

In view of the above, the present invention can improve the traction by a plurality of blocks formed by the circumferential grooves and the lateral grooves and the sipes formed in the blocks while maintaining the rigidity of the blocks. The aim is to obtain a pneumatic tire.

[0009]

According to the first aspect of the present invention, at least three circumferential grooves are provided along the circumferential direction of the tread, and a lateral groove is provided so as to intersect the circumferential groove. A studless specification pneumatic tire in which blocks divided by the circumferential grooves and the lateral grooves are formed, and a sipe is formed for each of the blocks, wherein a center side divided by the circumferential grooves is provided. The block has a two-row configuration, and the two-row blocks are arranged in the same phase in the circumferential direction.

According to the first aspect of the present invention, since the blocks on the center side have a two-row configuration and the two-row blocks have the same phase, the traction effect of the two-row blocks is simultaneously exhibited. For this reason, the starting and climbing performance particularly on ice can be improved. Further, to obtain this effect, the blocks are not subdivided, so that the rigidity of the blocks is not reduced.

According to a second aspect of the present invention, in the first aspect, the circumferential groove is formed in a zigzag shape.

According to the second aspect of the present invention, by forming the circumferential groove in a zigzag shape, braking performance on a wet surface (including on snow and ice) can be improved. Also, since the amplitude of the zigzag greatly depends on the braking performance, the larger the amplitude, the better. However, conversely, from the new (early wear) to the middle wear, the vicinity of the peak of the shoulder rib is increased. It is desirable to set an appropriate amplitude because the uneven wear performance centered on the heel and toe wear of the steel is reduced.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a protrusion is formed at the bottom of the circumferential groove on the shoulder side. .

According to the third aspect of the present invention, by forming the protrusion, when the stone on the road surface tries to enter the circumferential groove (when the groove tries to bite the stone), the protrusion is formed. Thereby, the intrusion of the stone can be suppressed. ,

[0015]

FIG. 1 shows a pattern (a part) of a tread 102 of a pneumatic tire 100 of a studless specification according to the present embodiment.

A plurality of lug grooves 104 are formed in the shoulder of the tread 102 at a predetermined pitch along the tire circumferential direction.

The lug grooves 104 formed at both ends in the width direction of the tire have a point-symmetrical shape that can obtain the same effect (traction effect) even if the lug groove 104 rotates in any direction before and after the tire. I have.

A groove 106 (hereinafter referred to as a circumferential groove) is formed in the tread 102 in the circumferential direction. The three circumferential grooves 106 are formed at a uniform pitch. Further, transverse grooves 110 are provided at predetermined pitches along the circumferential direction so as to cross the circumferential grooves 106. With the circumferential groove 106 and the lateral groove 110,
The tread 102 is divided into four along the tire width direction, and each of the four divided areas is subdivided by the lateral groove 110, and as a result, a plurality of blocks 112 are formed.

The circumferential groove 106 is formed in a zigzag shape by forming a step in the shape of the side surface of the block 112 in a crank shape, and forming a step at the step between the adjacent blocks 112 to be convex and the step facing the concave. Is formed. The purpose of the zigzag shape is to improve braking performance. That is, the greater the zigzag amplitude, the better the braking performance.

In each of the blocks 112, two sipes 114 are formed. Each of these blocks 11
One of the two sipes 114 in block 2
Approximately 2/3 to 3/4 is cut out from one side surface of the block 2, and a terminal end portion (a round hole 114A) is present before reaching the other side surface of the block 112. On the other hand, of the two sipes, the other is ／ from the other side of the block 112.
Approximately 3/4 is cut out, and a terminal end portion (a round hole 114A) exists before reaching the other side surface of the block 112.

Here, the circumferential groove 106 on the shoulder side,
That is, between the two circumferential grooves 106 except for the center of the tire, two rows of blocks 112 are arranged in the circumferential direction with the center-side circumferential groove 106 interposed therebetween.

The two rows of blocks 112 are in phase with each other. This will be described with reference to the schematic diagram of FIG. 2. FIG. 2A shows a case where the blocks 112 arranged in two rows have the same phase, and FIG. This is the case where the phases are shifted by one. This figure 2
As can be understood from the above, the in-phase indicates the relative positional shift amount between the blocks 112 arranged in two rows, and in the present embodiment,
The shift amount is zero.

In this in-phase structure, since the traction properties of the two rows of blocks 112 are simultaneously exhibited, a great amount of traction can be obtained particularly when starting on ice or climbing a slope. .

A protrusion 116 is formed at the bottom of the circumferential groove 106 on the shoulder side along the circumferential direction to prevent the circumferential groove 106 from biting stones.

The operation of the present embodiment will be described below.

The two rows of blocks 112 sandwiched between the two circumferential grooves 106 on the shoulder side are arranged in the same phase, so that these two blocks 112 are positioned at the same time with respect to the road surface (ice surface). Edge effects are found. That is, since the total effect of the traction in one round of the tire is substantially determined by the number of the blocks 112, for example, when the tires are arranged alternately (a phase shift of 1/2) as in the related art, the number of times the traction works is Although it increases twice,
Each time the traction effect is reduced by half. Therefore, in this embodiment, by using two rows at the same time, the number of times the traction works is reduced to と し, the traction effect of one time is doubled, and a tire excellent in starting and climbing performance on ice can be obtained. Can be.

In this case, since the traction effect interval is widened, the shoulder-side block 112 has a half phase with respect to the block 112 in the center two rows, so that the original traction effect is maintained. be able to.

Also, by setting the two rows of blocks 112 at the center to be in phase, when the vehicle is idle, it comes into contact with the road surface in a narrow area around the center in the tire width direction, and traction can be obtained only in this narrow area. Even if it is not possible, it is possible to obtain traction with the same force as in contact with the road surface in all areas in the tire width direction as in the case of fixed loading.

Further, in the above embodiment, the surface area of each block 112 is not different from the surface area of the block of the tire having the conventional structure, so that the rigidity of the block 112 can be maintained as before.

In the present embodiment, a tire having three circumferential grooves 106 has been described as an example. Therefore, the pitches of the three circumferential grooves 106 are the same, and the circumferential grooves located at the center are the same. Two rows of blocks 11 sandwiching 106
2, the two rows of blocks 112 have the same phase. However, as shown in FIG.
In the case of a tire provided with a groove, the pitch of the two circumferential grooves 106 on the middle side is set to be twice the pitch of the first and second circumferential grooves 106 from the end of the tire. A block 112 having the same shape formed between the two circumferential grooves 106 sandwiches a groove equivalent to the circumferential groove (here, a groove 120 having a width smaller than the circumferential groove 106). It has a two-row configuration. The same effect can be obtained by making the two rows of blocks 112 have the same phase.

As described above, when the number of the circumferential grooves 106 is three or more and an odd number, the circumferential grooves 106 located at the center of the tire are not provided.
Are interposed in two rows of blocks 112 having the same phase, and when the circumferential groove is an even number, the middle 2
The pitch of the circumferential grooves 106 is made larger (approximately twice) than the pitch between the other circumferential directions, and two rows of blocks 112 are formed between the widths that are about twice as large as the pitches between the circumferential grooves 106. By setting it to 2
It can be approximately twice the traction obtained in one block. Also, at this time, since a structure that causes a decrease in rigidity such as increasing the number of blocks 112, that is, reducing a unit surface area of the block, is not taken, there is a trade-off between improvement in traction and improvement (maintenance) in rigidity. Can be obtained at the same time. (Test Example) A traction test on indoor ice was performed on the tire applied to the present embodiment. At this time, the conventional product was set as a comparative object, and the μ value on ice of this comparative product was set to 100 (index standard).

The conditions such as applicable tires are as follows. Vehicle: 2-DD truck Tire size: 11R22.5 14PR Rim width: 825 Internal pressure: 700 KPa Load: 1500 kg (100% regular load = 2700 k
g) Temperature on ice: -5 ° C As a result of the test, the tire according to the present embodiment is one tire less than the conventional tire.
A 0% increase in traction effect (index 110) was obtained.

[0033]

As described above, the pneumatic tire according to the present invention maintains the traction of the blocks formed by the circumferential grooves and the lateral grooves and the sipe formed in the blocks while maintaining the rigidity of the blocks. It has an excellent effect of being able to improve while improving.

[Brief description of the drawings]

FIG. 1 is a developed plan view (partly) of a tread of a pneumatic tire according to the present embodiment.

FIG. 2 is a model diagram showing a difference in phase, (A) is a schematic diagram of the tread pattern of the present embodiment (same phase),
(B) is a schematic view of a conventional tread pattern (1/1).
2 phase shift)

FIG. 3 is a tire tread pattern diagram (four circumferential grooves) according to a modification.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 tire 106 circumferential groove 110 lateral groove 112 block 114 sipe 116 protrusion

Claims (3)

[Claims] At least three along the circumferential direction of the tread
By providing the circumferential grooves and providing the transverse grooves so as to intersect with the circumferential grooves, blocks divided by the circumferential grooves and the transverse grooves are formed, and a sipe is formed for each block. The pneumatic tire of the studless specification described above, wherein the blocks on the center side separated by the circumferential grooves are formed in two rows, and the blocks in the two rows are arranged in the same phase in the circumferential direction. A pneumatic tire, characterized in that: 2. The pneumatic tire according to claim 1, wherein the circumferential groove is formed in a zigzag shape. 3. A projection is formed at the bottom of the circumferential groove on the shoulder side.
Or the pneumatic tire according to claim 2.