JPH03204311A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To enable on-the-ice performance to be maintained up to the limit of wear, in the pneumatic tire for a bus or the like, by forming a siping that is extended in the direction of the tire shaft at a prescribed inclination in the block at the peripheral part of the tread, into a prescribed V-shape in the longitudinal section so as to have a specific groove width and groove depth. CONSTITUTION:In a block pattern formed by longitudinal grooves GR and lateral grooves GL, sipings 5 each of which has an inclination larger than 20 degrees and less than 90 degrees to the circumferential direction and has a groove width less than 0.8 mm, are separately provided in the tire axial direction in the block 3 formed in the peripheral part of a tread. And a V-shape having the deepest part F in the central region m between the points P2, P2 each of which is apart from the central position P1 between both side surfaces K1 and K2 of the siping 5 by 0.25 times the siping length l is formed. The depth DS of the groove of the siping 5 is set to be greater than 1.0 time and less than 1.2 times the depth DG of the longitudinal groove. By this constitution, on-the-ice performance maintainability can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention maintains on-ice performance such as traction and braking performance on icy and snowy roads even when the tread surface is worn close to the wear limit. Moreover, the present invention relates to a pneumatic tire that can improve uneven wear resistance.

[Conventional technology]

Vehicles such as passenger cars, trucks, and buses often travel on icy and snowy roads in winter and during snowfall, in addition to traveling on ships.

For driving on such icy and snowy roads, spiked tires, in which chains are attached to tires or spikes are driven into the tires, have conventionally been used. However, in recent years, due to road surface damage and dust pollution caused by chains and spikes, people are refraining from installing spiked tires and chains with hard spikes, and so-called spikeless tires without spikes are being used. .

Conventionally, in the case of such spikeless tires, performance on ice has been improved by forming a block pattern of blocks on the tread surface and arranging a plurality of sipings on the blocks in the axial direction of the tire. Further, it is desirable that the groove depth of the siping is deep in consideration of the amount of wear on the tread surface.

[Problem to be solved by the invention]

However, when the groove depth of the siping is formed to be deep over the entire surface of the block, the rigidity of both ends of the block is lower than that of the center, and uneven wear is likely to occur in these end regions.

The present invention is based on the fact that the groove bottom of the siping is formed in a figure 7 shape with an oblique groove bottom extending from the deepest part near the middle position between both surfaces of the block in the axial direction of the tire to the upper edges of both sides. A pneumatic tire that can maintain on-ice performance such as indexability and braking performance even when the tread surface is worn close to its wear limit, and that can reduce uneven wear and improve durability when driving on general roads. intended to provide.

[Means to solve the problem]

The present invention forms a block pattern consisting of blocks partitioned by a plurality of vertical grooves extending in the circumferential direction and a plurality of lateral grooves extending in a direction crossing the circumferential direction in the tread portion of a tire, and at least In each block of the block row along the edge, siping is provided at intervals in the tire circumferential direction at an angle of 20 degrees or more and 90 degrees or less with respect to the circumferential direction and extends between both sides of the block in the tire axial direction, The groove width (Ws) of the siping is 0.
．． 8fi or less, and the siping is 0 of the siping length CI) centered at the intermediate position between the two side surfaces.
．． The siping groove has a figure 7 shape with an oblique groove bottom extending from the deepest part to the upper edges of both side surfaces provided in the central region (ffl) between the separation points separating 25 times, and the depth of the siping groove from the top surface of the block at the deepest part. (DS) and the groove depth (DG) of the vertical groove, the ratio DS/DC is 1.0 or more and 1.2 or less.

[Effect]

The block along the trend edge is provided with sipes that extend between both sides of the block in the axial direction of the tire, making it possible to drive on ice and snow.

Further, since the siping is set at an angle of 20 degrees or more and 90 degrees or less with respect to the circumferential direction, it is possible to improve the followability of the tread surface to the road surface, and improve the track length, wear resistance, and wet performance.

Furthermore, the groove bottom of the siping is shaped like a 7-shape, and the groove depth DS at the deepest part is equal to or greater than the groove depth DC of the vertical groove and is 1.2.
This prevents a decrease in rigidity on both sides of the block's siping, and even if the tread surface wears close to its wear limit, the siping is closed on both sides, increasing the rigidity of the block. It is possible to suppress the progression of uneven wear and improve durability without degrading on-ice performance such as traction and braking performance on icy roads.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, the pneumatic tire 1 of the present invention has a tread portion 2
A block pattern consisting of blocks partitioned by a plurality of vertical grooves GR...- extending in the circumferential direction and a plurality of lateral grooves GL...- extending in a direction intersecting the circumferential direction is formed. Sipings 5, each having a groove bottom 4 shaped like a 7-shape, are spaced apart in the tire circumferential direction on the block 3 of the tire. In this embodiment, the horizontal grooves GL are formed to be slightly shallower than the vertical grooves GR.

The pneumatic tire 1 also includes sidewall portions 13.13 extending inward in the tire radial direction from both ends of the tread portion 2.
and a bead portion 15.15 located at the inner end in the radial direction of the sidewall portion 13, and a toroidal carcass 17 passing through the sidewall portion 13.13 and the tread portion 2 between the bead cores 16.16. The frame is passed over and a belt layer 19 is provided on the radially outer side and within the tread portion 2.
will be arranged.

The carcass 17 has a carcass cord connected to the equator C of the tire.
On the other hand, in this embodiment, it is a so-called radial or semi-radial direction arrangement body arranged at an angle of 30 degrees to 90 degrees,
In addition to steel cords, fiber cords such as nylon, polyester, rayon, and aromatic polyamide are used as carcass cords.

In this embodiment, the belt layer 19 has two belt plies arranged from the carcass 17 side toward the outside in the radial direction of the tire.

Further, the belt layer 19 includes belt cords arranged at an angle on each belt braai and crossing each other, and the belt cords are made of steel cords and fiber cords such as nylon, polyester, rayon, aromatic polyamide, etc., similarly to the carcass 17. is used.

In this embodiment, the longitudinal grooves GR are arranged in parallel with a central longitudinal groove GRI arranged on the equator C of the tire, and on both sides of the central longitudinal groove GR1 with a space therebetween. including a pair of side longitudinal grooves GR2, GR2, and a central longitudinal groove GR1;
Between the side longitudinal grooves GR2 there is a central block row 21.21, and between the side longitudinal grooves GR2 and the edge E of the tread portion 2 there is a block row 22.
22 is formed.

The side block rows 22 are partitioned by a plurality of side longitudinal grooves GL1- extending in the tire meridian direction, thereby forming rectangular side blocks 3.

The siping 5 extends in a straight line between the vertical groove GR2 on the side of the block 3 and the edge E of the tread portion 2, that is, between 1 and K2 on both sides of the side block 3 in the tire axial direction.
A plurality of strips are provided at intervals for each block 3.

The siping 5 is formed at an angle of 20 degrees or more and 9 degrees with respect to the circumferential direction.
Tilt at an angle of 0 degrees or less. When the inclination is less than 20 degrees, the ability of the tread surface to follow the road surface decreases, resulting in poor truncation, wear resistance, and wet performance.

Further, the siping 5 has a groove width Ws of 0.81 or less. When the groove width Ws exceeds 0.8, the trend part 2
When the sipes touch the ground, the pressure force with which both ends of the sipes are pressed against each other is reduced, and the rigidity of the side blocks 3 is reduced, resulting in a reduction in wear resistance.

Further, the sipes 5 are arranged on both sides [K] as shown in FIG.
1, K on both sides from the deepest part F provided in the central region m between 22.
It has a v-shape with a diagonal groove bottom 4.4 extending to the upper edges J1 and J2 of 2.

By making the shape of the groove bottom of the sipe 5 V-shaped in this way, it is possible to prevent a decrease in rigidity on both sides of the sipe of the block 3, and even when the tread surface is worn close to its wear limit, the sipe remains intact. The closure of both sides increases the rigidity of the block.

If the groove depth ratio DS/DC is less than 1.0, the braking performance, traction performance, and wet grip performance on icy and snowy roads will be poor, while if it exceeds 1.2, the overall rigidity of the block will decrease, and the Uneven wear occurs over the entire surface.

The siping 5 can have the deepest part F located at an intermediate position to form the groove bottom surfaces 4a, 4a of equal length, as shown by the dashed-dotted line in FIG. It is also possible to form two groove bottom surfaces 4b and 4C of unequal length by positioning the groove to one side within the region m, and the present invention can be modified into various embodiments.

〔Effect of the invention〕

Like a ridge, the pneumatic tire of the present invention is provided with siping on the side blocks, and the groove bottom of the siping extends from the deepest part provided near the intermediate position between both surfaces of the block in the axial direction of the tire to the upper surface of both side surfaces. Because it is formed in a figure 7 shape with a diagonal groove bottom, it can maintain ice performance such as traction and braking performance on icy roads even when the tread surface is worn close to the wear limit, and when driving on general roads. Reduces wear resistance and improves tire durability.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, FIG. 2 is a developed plan view showing its tread pattern, and FIG. 3 is an A-
It is an A-line sectional view. 0 2--Tread section, 3- Block 4.4 a,
4 b-=groove bottom surface, 5-・siping, 6...
Top surface, E-・Edge, F...Deepest part, GR...
Vertical groove, GL...-Horizontal groove, K1, K2--Side surface,
Jl, J2--upper edge, Pl--middle position, P2-
-...The dividing point! -・-Siping length, m...Central area.

Claims (1)

[Claims] 1 A block pattern consisting of blocks partitioned by a plurality of longitudinal grooves extending in the circumferential direction and a plurality of lateral grooves extending in a direction crossing the circumferential direction is formed on the tread portion of the tire, and at least at the tread edge. Sipings are provided in each block of the block row along the tire circumferential direction, and are inclined at an angle of 20 degrees or more and 90 degrees or less with respect to the circumferential direction and extend between both sides of the block in the tire axial direction, and the sipes are spaced apart in the tire circumferential direction. Groove width (Ws) is 0.81
The sipes shall be as follows, and the sipes shall extend from the deepest part provided in the central region (m) between the separating points separated by 0.25 times the sipe length (l) centered on the intermediate position between the sipes. It has a V-shape with an oblique groove bottom extending to the upper edge, and the ratio DS/DG of the siping groove depth (DS) from the top surface of the block at the deepest part to the groove depth (DG) of the longitudinal groove is 1. A pneumatic tire with a particle diameter of .0 or more and 1.2 or less.