JPH03159804A - Tread pattern of pneumatic tire - Google Patents

Abstract

PURPOSE:To uniform the balance of pattern rigidity in a tire with numerous blocks disposed with a specified pitch variation on the tread by forming a sipe additionally on each block with a specified pitch on a specific condition. CONSTITUTION:The tread 1 of a tire is provided with center ribs 2 disposed on the tread center C-C, and blocks 4 are disposed on the bilateral sides of the center ribs 2 through main grooves 3. The center rib 2 and each block 4 are disposed circumferentially with five pitch variations, that is, 0.75M<=SS<=0.85M, 0.85M<=S<=0.95M, 1.05M<=L<=1.15M, 1.15M<=LL<=1.25M. A sipe 6 is formed on each of blocks 4 of L and LL pitches on condition of 0.2H<=(h)<=0.9H, 0.1X<=(x)<=0.4X, where H: the depth of main groove 3, (h): the depth of sipe 6, X: the sum of length of sipe 6 in one M pitch, (x): the sum of length of sipe 6.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to SS pitch, S pitch,
This invention relates to a tread pattern of a pneumatic tire that employs five pitch variations: h pitch, L pitch, and LL pitch.

(Prior Art) Recently, as the quietness of vehicles has improved, there has been an increasing demand for tires to have lower noise.

One way to do this is to create a block with sidewalls in the tread with five pitch variations: SS pitch, S pitch, H pitch, L pitch, and LL pitch, with a pitch ratio of ±2.
When arranged at around 0%, the pattern rigidities of the SS pitch and the LL pitch will differ greatly.

In other words, when sipes are provided on the block to improve snow performance, especially in block patterns, etc., the sipes are inserted in the radial direction, so in the circumferential direction, as the pitch ratio increases, the length of the knife also increases. This is because in the radial direction, the knife length hardly changes even if the pitch is changed.

(Problem to be Solved by the Invention) Therefore, in the conventional tread structure, the pattern rigidity of each pitch is unbalanced, and noise reduction cannot be achieved.
Uneven wear of the block was likely to occur.

In view of the above-mentioned circumstances, the present invention provides a pneumatic tire that balances the pattern rigidity of each pitch and reduces noise and uneven wear by adding sipes to the L pitch and the 1, 1, and 1 pitches. The purpose is to provide a tread pattern of

(Means for Solving the Problems) The present invention provides a block 4 having a sipe 5 in a tread 1 via a main groove 3, with SS pitch, S pitch, H pitch,
L bit and I are arranged in the circumferential direction at a pitch of 1, and the pitch is 0. 75M≦SS≦0.85M 0.85M≦S≦0. 95M 1.05M≦L≦1.15M 1.15M≦LL≦1.25M In the tread pattern of pneumatic tires, the following technical measures are taken to achieve the above objectives. .

That is, the present invention provides: 0. A sipe 6 is additionally formed in each of the L pitch, 1, l, and bitge blocks 4 under the following conditions: 2H≦h≦0.911 0.1X≦x≦0.4× It is.

However, H: Groove depth h of the main groove; Groove depth X of the additional sipes; Total length of the sipes at one gate pitch X; Total length of the additional sipes (action) According to the present invention, Since the sibs 6 are additionally formed in the L-pitch block 4 and the LL-pitch block 4, the rigidity in the circumferential extending portion of the block becomes soft, and the balance of pattern rigidity becomes uniform.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

2 and 3, 1 is the tread of a pneumatic tire, and this trend 1 has a tread center C-
A center rib 2 is provided on C, and blocks 4 are disposed on the left and right sides of this center rib 2 via a main groove 3.

A sipe 5 is formed on the center rib 2 and each block 4, and the center rib 2 and each block 4, 4' are arranged in the circumferential direction with a 5-bit variation as shown in FIG.

That is, SS pitch, S bitch, gate pitch, and L
It is arranged with 5 pitch variations of pitch and LL pitch, and the pitch has the following relationship: 0.75M≦SS≦0
．． 85M 0.85M≦S≦0.95M 1. 05M≦L≦I. 15M 1.15M≦1,1,≦1.25M, and here, the size of each pitch is changed so that the SS pitch is around -20% of the gate pinch and the LL pitch is around +20% of the H pitch. It is said to be a pattern.

Among the blocks 4, the circumferentially extending portions of the blocks located within the L pitch and the LL pitch have 0.2■ ≦h ≦
0.911 0. Sipe 6 is additionally formed under the condition of IX≦x≦0,4X.

Here, ■ is the groove depth of the main groove, h is the groove depth of Sipe 6, and
is the sum of the sipe lengths in one N pitch, that is, X=L+Xz+Xz+---Lt+X++,
X is the sum of the lengths of the sipes 6 to be added.

In the above, the reason why 0.2■≦h≦0.911 is set is because
When h < 0.28, the sipe depth is too shallow and the effect of suppressing rigidity is reduced, and when h > 0.91, the sipe depth is too deep and the rigidity becomes abnormally low, causing damage such as rubber breakage. This is because h is a factor, and preferably h is 0.6H~
It is assumed to be 0.7H.

Also, if 0.1X≦× is less than this, the length of the sipe 6 will become extremely short and there is almost no function to suppress rigidity, and if If this happens, the sipe 6 will become abnormally long and cause damage such as rubber breakage. Therefore, preferably X is 0.2X to 0.3
It is assumed to be X.

Next, noise (index) and uneven wear (index) will be compared and explained between the tire according to the present invention and the tire according to the conventional example.

(Next page) Tire according to the present invention Tire according to the conventional example The above test results are shown in Figs. 4 and 5. Regarding noise, if the conventional example is 100, the present invention is 108, and regarding uneven wear. When the conventional example is 100, the present invention is 113.

(Effects of the Invention) The present invention is as described above, and by adding sipes to the L and LL pitch blocks in a tread pattern having 5 pitch variations, the pattern rigidity is evenly balanced, reducing noise and improving uneven wear. can be improved.

[Brief explanation of the drawing]

Fig. 1 is a developed view showing the right half of a part of the tread according to the embodiment of the present invention, Fig. 2 is a tread pattern diagram, Fig. 3 is an elevational view, and Figs. 4 and 5 are examples of the embodiment of the present invention. FIG. 6 is a test graph showing the noise index of the conventional example. FIG. 6 is a tread pattern diagram of the conventional example. 1...Tread, 3...Main groove, 4...Block,
5...Sipe, 6...Additional Sipe.

Claims (1)

[Claims] (1) The sipes (
5) are arranged in the circumferential direction at SS pitch, S pitch, M pitch, L pitch, and LL pitch, and the pitches are: 0.75M≦SS≦0.85M 0.85M≦S≦ 0.95M 1.05M≦L≦1.15M 1.15M≦LL≦1.25M In the tread pattern of a pneumatic tire, 0.2H≦h≦0.9H 0.1X≦x≦0. A tread pattern for a pneumatic tire, characterized in that sipes (6) are additionally formed in each of the L pitch and LL pitch blocks (4) under the condition of 4X. However, H: Groove depth h of the main groove; Groove depth X of the sipes to be added; Total length of the sipes in one H pitch x; Total length of the sipes to be added