JPH02303906A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve especially the performance on the ice by forming a lag groove out of a lateral part and a slant part, and inclining a transverse main groove and a transverse sub groove in the same direction as the lag groove, and also specifying each cross angle between each of these layers and a circumferential main groove in the same value. CONSTITUTION:Each lag groove 6 positioned separately in the width direction of a tire is made of a lateral part 7 positioned at the end of a tread 1 and a slant part 8 positioned in the vicinity of a circumferential main groove 2. And a transverse main groove 3 is inclined in the same direction as one slant part 8, and a transverse sub groove 4 is inclined in the same direction as the other slant part 8. Moreover, each cross angle, on the side of an acute angle, between the lag groove 6, the transverse main groove 3 and the transverse sub groove 4 and the circumferential main groove 2 is set to within the same range of, respectively, 60-85 deg.. Furthermore, the land part between each circumferential main grooves 2 is made into a block in the shape of an isosceles triangle. On the other hand, a sipe 13 is inclined in the same direction as the inclinatory direction of the transverse main groove 3 or the transverse sub groove 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to pneumatic tires, particularly studless tires for heavy-load vehicles, which do not sacrifice on-snow performance and uneven wear resistance. This advantageously improves on-ice performance.

(Prior Art) Conventionally known winter tires for heavy-duty vehicles include:
For example, some tires have a tread pattern as shown in FIG.

This means that a plurality of transverse grooves 51 extending in the width direction of the tire are arranged at equal intervals in the circumferential direction of the tire between two circumferential main grooves 50 extending in a zigzag shape in the circumferential direction of the tire. At the same time, between these circumferential main grooves, a surface circumferential main groove 50 also extends in a zigzag shape in the circumferential direction of the tire.
By arranging one circumferential sub-groove 52 parallel to the tread surface, a plurality of blocks 54 each having a planar shape approximately in the shape of an "L" are defined in the central portion of the tread surface portion 53, and On the outer side of each circumferential main groove 50 in the tire width direction, there are two blocks 55 that are bent in an approximately rlJ shape along each circumferential main groove 50, and the tips thereof are mutually connected. Each lug 56 bends away.
57.

When such a tire is transferred on snow, the edge portions of each block 54.55 and lug 56.57 extending in the width direction of the tire are dug into the snow, and the groove width of each groove is adjusted. By trapping snow into each groove based on the decrease during ground contact, on-snow traction performance, braking performance, etc. can be achieved.

By the way, when driving on ice with such a tire, the tread pattern as described above greatly lacks the edge component extending in the width direction of the tire.
It was virtually impossible to demonstrate satisfactory on-ice performance.

Therefore, as shown in FIG. 3, by providing transverse grooves 61 facing in the width direction of the tire between the three zigzag-shaped circumferential main grooves 60, blocks 61 are formed between the respective circumferential main grooves.
2, and from the circumferential main groove 60 at both end portions,
A shoulder lug 64 is defined by a plurality of lateral grooves 63 extending substantially in the width direction of the tire and reaching the tread edge, and further includes a respective block 62 and lug 64.
A tread pattern in which two or three short inclined sipes 65 are formed has been proposed.

According to this tire, the block 62 and the lug 64
Since the edge portion in the width direction of the tire is considerably increased compared to that of the tire described above, the performance on snow is far superior to that of the tire described above. However, even with this tire, the performance on ice was still unsatisfactory due to the lack of an edge portion in the width direction of the tire.

For this reason, in order to further increase the edge portion extending in the width direction of the tire, as in a studless tire for a passenger car, for example, as shown in FIG. It has also been proposed to form a large number of sipes 66, and it has been confirmed that this tire provides sufficiently satisfactory performance on both snow and ice.

(Problem to be Solved by the Invention) However, when the tires shown in Figure 4 are applied to heavy-duty vehicles such as trucks and buses, the load conditions of the tires are significantly more severe than those of passenger car tires. In many cases, the rigidity of the uneven parts classified by size 66 becomes too low, and uneven wear, so-called heel-and-toe wear, occurs on each uneven part. The wear far outweighed the benefit of improved ice and snow performance.

The present invention advantageously solves the problems of the prior art, and in particular, based on the effect of size, provides extremely excellent on-ice performance without sacrificing not only on-snow performance but also uneven wear resistance. The purpose is to provide a pneumatic tire that can.

(Means for Solving the Problems) The pneumatic tire of the present invention has two circumferential main grooves provided in the tread surface and extending linearly, and a circumferential main groove extending between these circumferential main grooves. A smoked main groove and a transverse minor groove that connect these grooves, a lug groove that extends from each circumferential main groove to the tread edge, and each land area divided by these grooves. sipes, wherein respective lug grooves are spaced apart in the width direction of the tire, and respective lateral sipes are located near the tread edge and extend substantially in the width direction of the tire. directional portion, and respective inclined portions that are located in the vicinity of the circumferential main groove and are inclined in opposite directions with respect to the lateral portions thereof, and the transverse main groove is arranged in the width direction of the tire. of lug grooves spaced apart to
a lug groove that is inclined in the same direction as either one of the inclined portions and that separates the transverse minor groove in the tire width direction;
In addition to inclining in the same direction as the other inclined portion, the groove width of this transverse sub-groove is made smaller than that of the transverse main groove, and each transverse sub-groove is It is combined with the transverse main groove at the continuous part to the groove, and the intersection angles of the lug groove, transverse main groove and sub-groove and the circumferential main groove on the acute angle side are all the same, and 60 to 85 °, and at least the land portion located between the two circumferential main grooves is a substantially isosceles triangular block, and the sipes are inclined in the same direction as the inclination direction of the transverse main groove or the sub-groove. The width of each sipe is 1.2 mm or less.

(Function) For traction performance on ice, braking performance, etc., it is effective to form a size in the land area of the tread, and it is especially effective to make each sipe extend in the width direction of the tire. However, when sipes are installed on the tires of heavy-duty vehicles, especially when driving on dry roads, the rigidity of the small land area divided by the sipes is overcome by the powerful axle torque. , as mentioned above,
Severe uneven wear occurs on the small land area, and by extension, on each land area.

In addition, when a plurality of sipes extending in the tire width direction are formed on each land portion, which often has an irregular planar shape, extremely small small land portions are defined at the corners of each land portion and other places. In many cases, these small land areas cannot contribute at all to improving on-ice performance, especially when each sipe is a so-called open sipe that opens at both ends of the land area.

Therefore, in the tire of the present invention, the intersection angle of the sipe with the linear circumferential main groove, in other words, the intersection angle with the tire equatorial plane is 60 to 85 degrees, more preferably 65 to 7 degrees.
By setting the angle to 5°, these sipes ensure sufficient penetration into the icy and snowy road surface, while effectively preventing the occurrence of uneven wear on the small land area divided by the sipes, and dividing the land area. Also, the extending direction of each groove is
By setting the intersection angle between these and the tire equatorial plane to be 60 to 85 degrees, more preferably 65 to 75 degrees, it is possible to effectively prevent the formation of small land areas that cannot contribute at all to improving performance on ice and snow. Even if small land areas occur, the amount of sipes generated is greatly reduced, thereby ensuring sufficient performance of the sipe function.

In other words, if the sipe angles and groove angles are aligned as described above, each small land area within each land area will simultaneously and effectively act on human power from the icy and snowy road surface. In other words, when the road surface input acts on each land area, each small land area leans against each other and supports human power equally. Unlike when the size is extended in the width direction of the tire, each small land area does not deform independently when stepping in and kicking off, so the amount of uneven wear on the -711 land area can be increased. can be reduced.

Here, considering the input load of the unit land part, for example, if the respective edges of the land part on the stepping-in side and the kick-out side are extended parallel to each other at a predetermined acute angle with respect to the tire equatorial plane, , a block with both side edges extending parallel to the equator line, with sipes extending in the width direction of the tire, and a block with the same shape and dimensions as that block, on the stepping side and kicking side. If a certain amount of human force is applied from the stepping side of the block to the end edge of the block and the block with parallel sipes, the sipe length of the latter block will be longer than that of the former block. By increasing the length, the input support force per unit length that acts on the edge portion of the small block divided by the sipe becomes smaller, and the latter input support force also acts on the edge portion of the small block. The edges of the block are also almost the same, and the input load on the latter land part is smaller than that on the former land part. Therefore, as in this invention, the sipes are inclined in a certain direction together with the transverse main groove or minor groove. Even in this case, the input load on the land portion is effectively reduced, and uneven wear resistance and wear resistance are improved. In addition to these, when the edge length of the land portion and the sipe length are made equal, the wear of each small land portion can be made sufficiently uniform.

By the way, in this invention, the intersection angle of the transverse main groove, the sub-groove, the inclined portion of the lug groove, and the sipe with respect to the tire equatorial plane is set to 60 to 85 degrees.If the angle is less than 60 degrees, the ice and snow performance will deteriorate, and if it exceeds 85 degrees. This is because the form of wear on the land portion after driving becomes significantly worse.

On the other hand, in the tire of the present invention, the lug grooves formed in a portion of each shoulder of the tread are provided with sloped portions that slope in opposite directions to each other, so that when the tire is transferred, the lug grooves are not easily penetrated into the lug grooves. The snow can be smoothly discharged to the rear side in the rotational direction of the tire, thereby advantageously improving the snow surface grip of the tire.

In addition, by specifying the intersection angle of the shoulder lug groove with the tire equatorial plane as described above, the lug groove angle will almost match the tire's kick-out shape, so that when the lug groove is separated from the snow surface, - The entirety of the lug grooves is released from the road surface almost simultaneously, and in addition, the groove width of the lug grooves is quickly expanded by the removal of the load, so that the snow that has entered the lug grooves can be removed almost completely from there. can be discharged.

Moreover, by making the transverse main groove and the transverse sub-groove extend in opposite directions relative to the tire's equatorial plane, snow-covered running performance, especially turning performance, is improved based on the action of the edges of the transverse groove. It can be exerted equally in either direction.

Here, we need to balance the mutually contradictory characteristics that a large ground contact area is required to improve performance on ice, and wide grooves and groove edge force are required to improve performance on snow. In order to improve on-snow performance, the transverse main grooves are made thicker, and the transverse minor grooves are made thinner to increase the ground contact area, while the grooves improve on-snow performance.

Also, by merging both ends of each sub-groove with the end portion of the main transverse groove, snow clogging in the grooves is prevented. That is, in general, snow is trapped in a compressed state at the portion where a transverse groove intersects with another transverse groove, making it difficult to discharge the snow even if the groove is released from the load.
Since the combined portion of both transverse grooves opens into the circumferential main groove, snow can be discharged from the groove sufficiently smoothly.

Furthermore, by making the land section divided by each of these transverse grooves and the two circumferential main grooves into a block in the shape of an approximately isosceles triangle, this also improves snow turning performance. Make it even.

Here, the width of the size formed on the land is 1.2 mm.
The reason for the following is that the water generated between the tire and the water surface on ice is absorbed into the sipe by capillary water absorption, and if it exceeds 1.2 mm, there is no sufficient water absorption. This is because it cannot be demonstrated.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a tread pattern showing one embodiment of the present invention.

Note that the inner structure of the tire is the same as that of a conventional general radial tire, so illustration thereof is omitted here.

In the figure, 1 indicates a tread surface portion, and 2 indicates a circumferential main groove provided on the tread surface portion 1 and extending linearly in the circumferential direction of the tire.

Here, ``located at predetermined intervals, for example 11
．． The transverse main grooves 3 extending between and connecting two circumferential main grooves having a groove width of 0 mm are moved in a direction such that their intersecting angle with the circumferential main groove 2 is 70", to the right in the figure. The width of each groove is 9.0.
mm, and this also means that the transverse minor groove 4 extending between the two circumferential main grooves is directed in the direction opposite to the transverse main groove 3 with respect to the circumferential main groove 2, and It extends downward to the left in the figure in the direction where the angle of intersection with the main groove 2 is also 70°, and the width of the groove is 4.5 m, and further,
By combining both ends of each transverse minor groove 4 into the transverse main groove 3 at the continuous portions thereof to the respective circumferential main grooves 2, an approximately isosceles triangular shape is formed between both circumferential main grooves. A plurality of blocks 5 are divided into sections.

Further, in the outer portion of each circumferential main groove 2 in the tire width direction, a plurality of lug grooves 6 extending from each circumferential main groove 2 to the tread end are provided at predetermined intervals in the circumferential direction. The portion of each lug groove 6 located near the tread end is the lateral portion 7 that substantially extends in the tire width direction, and the portion of the lug groove 6 located near the circumferential main groove is In the relative relationship with other lug grooves 6 located apart in the width direction of the tire, an inclined portion 8 is inclined in mutually opposite directions with respect to the lateral portion 7, and the 9 circumferential main direction of the inclined portion 8 is The angle of intersection with groove 2 is also 70°.

According to this, the kick-out ground contact shape shown by the imaginary line in the figure almost matches the inclination angle of the lug groove, so as mentioned above, snow that has entered the lug groove can be discharged from there. It can be made extremely smooth.

Further, in the illustrated example, the lug groove 6 extends from the tip of the lateral portion 7 in a direction opposite to the inclined portion 8 with respect to the tire equatorial plane, and continues to the circumferential main groove 2 at an angle of 70°. By providing the narrow groove 9, the narrow groove 9, the inclined portion 8, the circumferential main groove 2, and the block 1 having an isosceles triangular shape are formed.
In addition to partitioning the block 1, another block having substantially the same shape and dimensions as the block 11 is formed by a bent groove 12a formed between the blocks and having an intersection angle of 70° with the circumferential main groove 2. 12b.

In this way, where each of the land areas is divided, the present invention further provides that each of them is directed in the same direction as the transverse main groove 3 or the transverse sub-groove 4, in the same direction as the transverse main groove 3 in the figure. By providing two or more inclined sipes 13 for each land portion, three or more unland portions 14 are formed in each land portion.

According to this tire, by setting the intersection angle of each groove with the circumferential main groove 2 with the exception of the circumferential main groove 2 to be 70 degrees, maximum ice and snow performance can be achieved while ensuring the wear pattern after running to some extent. can be demonstrated.

In addition, by setting the intersection angle of each sipe 13 provided in the land area with the circumferential main groove 2 to 70°, as mentioned above, the unland area divided by the sipe 13, and by extension each land area. In addition, each uneven portion 14 is made to effectively contribute to improving the ice and snow performance, and furthermore, compared to the tire shown in FIG. The amount of uneven wear can be greatly reduced.

By making the extending directions of the sloped portions 8 of the lug grooves 6 opposite to each other in the width direction of the tire, it is possible to improve the snow drainage performance and the tire's grip on the snow surface. Moreover, when driving on road surfaces other than icy and snowy roads, such as wet roads, it is possible to ensure stable wet performance with excellent drainage performance.
In addition, when turning left and right on a dry road surface, it is possible to generate a reaction force similar to that of a propeller to ensure stable performance.

[Comparative example]

A comparative test of the invention tire, conventional tire, and comparative tire regarding performance on snow, performance on ice, and uneven wear resistance will be described below.

◎Test tire size: 10.0OR20 - Invention tire - Tire with the tread pattern shown in Fig. 1 - Conventional tire - Tire with the tread pattern shown in Fig. 2 - Comparative tire I - Tire with the tread pattern shown in Fig. 3 - Comparative tires ■ Tires with tread patterns shown in Figure 4 ◎Test method Performance on snow and performance on ice were both evaluated by measuring traction force during actual vehicle driving.
Uneven wear resistance was evaluated by measuring the amount of step difference between the stepping side and kicking side of each block after running 20,000 km on a dry road surface.

◎Test Results When the above test results are expressed as an index of 100 for conventional tires, the results are as shown in the table below.

Note that the larger the index value, the better the result.

According to this table, compared to the conventional tire, the invented tire has
It is possible to exhibit on-snow performance to the same level as comparative tires I and II, with almost no decrease in uneven wear resistance, and to significantly improve on-ice performance compared to that of conventional tires. is clear.

(Effects of the Invention) Thus, according to the present invention, on-ice performance can be improved to a sufficiently satisfactory degree without sacrificing uneven wear resistance and on-snow performance.

[Brief explanation of drawings]

FIG. 1 shows a tread pattern showing an embodiment of the present invention, FIG. 2 shows a tread pattern showing a conventional example, and FIGS. 3 and 4 show tread patterns showing the proposed technology, respectively.

Claims (1)

[Claims] 1. Two circumferential main grooves that are provided in the tread surface and extend linearly, and a transverse main groove that extends between and connects these circumferential main grooves. A pneumatic tire comprising a minor groove, a lug groove extending from each circumferential main groove to a tread edge, and a sipe provided in each land portion divided by each of these grooves, The respective lug grooves are located apart from each other in the width direction, and the respective lateral parts are located in the vicinity of the tread end and extend substantially in the width direction of the tire, and the respective lug grooves are located in the vicinity of the circumferential main groove. and respective inclined portions that are inclined in opposite directions with respect to their lateral portions, and the transverse main groove is configured to be the same as one of the inclined portions of the lug grooves spaced apart in the width direction of the tire. a lug groove that is arranged to be inclined in the direction of and separates the transverse minor groove in the tire width direction;
In addition to being arranged so as to be inclined in the same direction as the other inclined portion, at least the groove width of this transverse sub-groove is made smaller than that of the transverse main groove, and each transverse sub-groove is It is combined with the transverse main groove at the continuous part to the direction main groove, and the intersection angles of the lug groove, transverse main groove and sub-groove and the circumferential direction main groove on the acute angle side are all the same, and 60
~85°, and the land portion located between the two circumferential main grooves is made into an approximately isosceles triangular block, and the sipes are inclined in the same direction as the inclination direction of the transverse main groove or the sub-groove. A pneumatic tire in which the width of each sipe is 1.2 mm or less.