JPH07186631A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To prevent the generation of the shoulder drop abrasion toward a tread shoulder part. CONSTITUTION:On a tread surface part 1, the first and the second inclined main grooves 2 and 3 which cross in a nearly X shape are formed, and each of these inclined main grooves 2 and 3 is allowed to cross at plural places, and the angle for the tire circumferential direction of each side part 2c of the first inclined main groove 2 is set larger than the angle of the center part 2a, and the angle for the tire circumferential direction of each side part 3b of the second inclined main groove 3 is set smaller than the angle of the center part 3a. As for the inclined main grooves 2 and 3, each groove width at the center parts 2a and 3a is set wider than that of the side parts 2c and 3b, and the negative ratio of the tread surface part 1 is reduced in a certain tendency, towards the side division from the center division of the tread surface part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tread pattern of a pneumatic tire, in particular, a pneumatic radial tire for passenger cars, and more particularly, to effectively prevent shoulder drop wear of a tread shoulder portion of a tread tread portion. It provides uniform wear.

[0002]

2. Description of the Related Art In a conventional tread pattern for a pneumatic radial tire for passenger cars, 3 to 5 circumferential main grooves extending continuously in the tire circumferential direction are provided on the tread tread portion, and the circumferential main groove arrangement is provided. Under the control of, the negative rate distribution in the tread width direction is generally uniform at any position.

[0003]

However, in such a conventional technique, since the negative ratio distribution in the tread width direction is substantially uniform, the tread shoulder portion of the front wheel tire, which is a steered wheel, is particularly important. However, there is a problem that shoulder drop wear due to a large input thereto is likely to occur, and in addition, when disposing the circumferential main groove on the tread tread, rain that may be formed on the road surface. Since it is necessary to select the position of each circumferential main groove to prevent the tire from wobbling due to the groove, in other words, the occurrence of rain groove wander, it is ideal for shoulder drop wear over all tire sizes. There was a problem that it was impossible to realize the groove allocation.

The present invention has been made as a result of studies to solve the above-mentioned problems of the prior art, and the inclined main groove is used instead of the circumferential main groove continuously extending in the circumferential direction of the tire. By arranging the grooves, excellent drainage performance is ensured, and under the volume distribution of the tread rubber as required, shoulder drop wear of the tread shoulder part is effectively prevented, and the entire tread tread part The purpose of the present invention is to provide a pneumatic tire that achieves almost uniform wear.

[0005]

The pneumatic tire of the present invention is provided with two kinds of inclined main grooves, a first and a second, which intersect substantially in an X shape on the tread tread, and each of these inclined main grooves is formed. , Intersecting each other at a plurality of positions to make the angle of each side portion of the first inclined main groove with respect to the tire circumferential direction larger than that of the central portion thereof, while each of the second inclined main grooves The angle of the side portion of the tread with respect to the tire circumferential direction is made smaller than that of the central portion of the tread, and the groove width of the central portion is made wider than that of the side portion in at least one of the inclined main grooves. The negative ratio of the surface portion is decreased from the central area of the tread surface to the lateral area.

[0006] Preferably, the angle of the first inclined main groove with respect to the tire circumferential direction is 0 to 20 ° at the central portion thereof.
And at the side area 60 to 80 °,
The angle of the second inclined main groove with respect to the tire circumferential direction is 30 to 50 ° at its central portion and 0 to 15 ° at its side portions,
Also preferably, for the volume of the tread rubber between the tread center and the 1/4 position of the tread width, the volume of the tread rubber between the 1/4 position and the tread edge is 1.3 to 1.6. Double.

Further, here, it is preferable that the groove width of the central portion of the first inclined main groove is narrower than that of the central portion of the second inclined main groove, and further, the first and second inclined main grooves are formed. It is preferred to terminate the grooves in the lateral areas of the tread tread and open their respective groove ends to the tread width via sipes or other narrow grooves. When the narrow groove is a sipe, it is preferable that the transverse cross section of the sipe has a flask shape.

In addition, in this tire, the circumferential length of the second inclined main groove is preferably longer than that of the first inclined main groove, and more preferably the length of the second inclined main groove. Is longer than the contact length on the contact surface of the tire during load rolling.

[0009]

[Function] With this pneumatic tire, the tread surface is
By providing an inclined main groove that extends obliquely with respect to the tire circumferential direction, excellent drainage can be ensured and the generation of rain group wander can be effectively prevented.
Further, by intersecting the two types of inclined main grooves in an X shape on the tread tread portion, it is possible to eliminate the one-way flow component at the time of rolling of the tire and ensure straight rolling.

By intersecting each of the two types of inclined main grooves with each other at a plurality of points, thereby defining a block row along the inclined main grooves, an edge of each block has a low friction coefficient. It effectively affects the running performance on slippery roads, and also improves the ground contact of the entire tread. Further, the angle of each side portion of the first inclined main groove with respect to the tire circumferential direction is made larger than that of the central portion thereof, while the side circumferential portion of each side portion of the second inclined main groove is arranged in the tire circumferential direction. A smaller angle to that of the central portion prevents the corners of the block defined by the tilted main grooves from becoming too acute or obtuse.

By the way, these things mean that the angle of the first inclined main groove with respect to the tire circumferential direction is 0 at the central portion thereof.
The angle of the second inclined main groove with respect to the tire circumferential direction is 30 to 50 ° at the central portion and 0 to 15 ° at the side portions. This is especially noticeable when That is, by setting the inclination angle of the central portion of the first inclined main groove to be 0 to 20 °, a sufficient wet drainage function in the front-rear direction can be achieved, and at the same time, low noise can be realized. Moreover, by setting the inclination angle of the side part thereof to 60 to 80 °,
Sufficient traction can be secured.

Then, the central portion of the second inclined main groove is
By setting the angle to -50 °, low noise and wet drainage can be achieved at the same time as the first groove without forming an extremely acute angle portion at the intersection with the first inclined groove. Further, by setting the inclination angle of the side portion thereof to 0 to 15 °, the difference in width between the blocks adjacent to each other in the circumferential direction of the block row defined on the grounding end side of the second groove can be reduced. The groove angle change from the center is smooth, and wet drainage can be secured.

Moreover, in this tire, the first and second tires are
In at least one of the inclined main grooves of the above, by making the groove width of the central portion wider than that of the side portion, it is possible to further improve the wet drainage property, and together with this, the tread tread portion By negatively decreasing the negative ratio from the central area to the side areas and increasing the tread rubber volume particularly at the tread shoulder area, it is possible to effectively prevent shoulder drop wear on the tread shoulder area. can do.

It should be noted that this means that the tread rubber volume between the tread center and the 1/4 position of the tread width is 1.3% less than the tread rubber volume between the 1/4 position and the tread edge. It is especially effective when set to ~ 1.6 times. In other words, if it is less than 1.3 times, shoulder drop wear cannot be sufficiently prevented, and if it exceeds 1.6 times, wear of the tread center part becomes severe.

Further, when the groove width of the central portion of the first inclined main groove is made narrower than that of the central portion of the second inclined main groove, the divided block becomes too thin and the block rigidity is increased. There will be a shortage.

Furthermore, by terminating the first and second inclined main grooves in the side regions of the tread tread portion, it is possible to prevent heel and toe wear from occurring on the tread shoulder portion, and By opening each groove end to the tread end through a narrow groove such as a sipe or the like, it is possible to enhance the ground contact property of the tread shoulder portion and enhance the edge effect for a low μ road. Here, in the case where the narrow groove is sipe, when the cross-sectional shape of it is flask-shaped,
Wet drainage can be ensured while effectively preventing heel and toe wear.

Further, in this tire, the circumferential length of the second inclined main groove is made smaller than that of the first inclined main groove by reducing the angle within the angular range of the side portion described above. In this case, the drainage property of the side portion in the front-rear direction can be improved, and the edge of the land portion sectioned by the portion can contribute to the generation of the lateral slip resistance when the lateral force acts. Then, by making the length of the second inclined main groove longer than the ground contact length on the ground contact surface of the tire during load rolling, at least one end thereof is extended beyond at least one of the stepping end and the kicking end. If it is present, the drainage can be further improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a tread pattern showing an embodiment of the present invention. Since the internal reinforcing structure of the tire is similar to that of a general radial tire, the illustration is omitted here.

In this example, the tread tread portion 1 is provided with a first inclined main groove 2 extending upward to the right and a second inclined main groove 3 extending upward to the left in the figure, respectively. The inclined main grooves 2 and 3 are intersected with each other in an X shape, and a plurality of intersections are provided for each inclined main groove 2 and 3.

Preferably, the angle of the first inclined main groove 2 with respect to the tire circumferential direction is 0 at the central portion 2a thereof.
The range is 20 °, and the side portion 2c smoothly connected to the central portion 2a through the curved portion 2b is 60 to 60.
In the range of 80 °, the same angle of the second inclined main groove 3 is 30 to 50 ° at the central portion 3a thereof and 0 to 0 at the side portion 3b extending from the central portion 3a by being smoothly curved.
By setting the angle to 15 °, the angle of each side portion 2c of the first inclined main groove 2 with respect to the tire circumferential direction is made larger than that of the central portion 2a thereof, while the angle of the second inclined main groove 3 is increased. The angle of each side portion 3b with respect to the tire circumferential direction is made smaller than that of the central portion 3a thereof.

Further, in at least one of the first and second inclined main grooves 2 and 3, both in the figure, the central portion 2 is formed.
The groove widths of a and 3a are made wider than that of the side portions 2c and 3b, and the negative ratio of the tread tread portion 1 is set as shown in FIG.
As shown in the graph in FIG. 1, the tread tread portion 1 is preferably gradually decreased from the central area toward the side areas, and preferably, the tread center XX and the tread end side from the tread center portion 1/4 of the tread width. The volume of the tread rubber that exists between the 1/4 position and the tread edge is 1.3 compared to the volume of the tread rubber that exists between the tread rubber and
~ 1.6 times.

Also, this is preferably such that the groove width of the central portion 2a of the first inclined main groove 2 is narrower than that of the central portion 3a of the second inclined main groove 3, and preferably the first and second The second inclined main grooves 2, 3 are terminated in the lateral areas of the tread tread 1, and their respective groove ends are opened to the tread ends via narrow grooves, in the figure sipes 4, 5. in this case,
More preferably, the cross-sectional shape of sipes 4, 5 is sipes. Here, as the narrow groove, a groove having a width such that the groove walls do not contact each other when the tire rolls under load can be provided instead of the sipes 4 and 5.

In addition, in the tire of this example, the circumferential length of the second inclined main groove 3 is made longer than that of the first inclined main groove 2, and more preferably, the second inclined main groove 3 is formed. Its length,
Make it longer than the contact length of the tread contact surface.

Further, in the illustrated example, two auxiliary grooves 6 branching from the second inclined main groove 3 and projecting toward the tread end side are provided for each inclined main groove 3, and the auxiliary grooves 6 are adjacent to each other. By intersecting the side portion 3b of the second inclined main groove 3 that is formed, the block defined by both inclined main grooves 2 and 3 is divided into proper sizes, and at the same time, excellent grounding performance and traction performance are obtained. Is obtained.

Further, in each block defined by the inclined main grooves 2 and 3 or the auxiliary grooves 6, the ground contact of the blocks is improved, the water film is cut, and an edge on a road surface having a low friction coefficient is formed. A plurality of sipes that contribute to the effect and the like are provided, and in addition to the sipes 4 and 5 described above, the sipes 7 that open the auxiliary groove 6 at the tread end and the second inclined main groove 3 are provided in the tread shoulder portion. Edge effect groundability and a water film cutting function by providing sipe 8 which respectively intersects the side end portion 3b of each of them and disposing all of these sipe 4, 5, 7, 8 substantially evenly in the circumferential direction. Bring further improvement.

Further, in this example, each sipe 4,
By forming the shoulder sub-grooves 4a, 5a, 7a, 8a of 5, 7 and 8 in the vicinity of the tread end with somewhat wide shoulder sub-grooves,
The traction function is obtained by entering the ground contact surface after the middle stage of wear, and the traction effect during cornering is obtained when the product is new.

According to the tire constructed as described above,
Based on the above-described actions of the main parts, it is possible to effectively prevent occurrence of shoulder drop wear on the tread shoulder portion while maintaining excellent drainage performance.

[Comparative Example] A comparative test regarding the abrasion resistance level and the drainage property between the invention tire and the comparative tire will be described below. ◎ Test tire size is 185 / 70R14 and tread width is 130mm
Tires. Invention Tire 1 A tire having the tread pattern shown in FIG.
A tire having the dimensions shown in Table 1. Here, for the volume of the tread rubber between the tread center and the position 1/4 of the tread width, the volume of the tread rubber between the position 1/4 and the tread edge is 1.
42 times.

[Table 1]

Invention Tire 2 Each sipe formed on the tread shoulder has a flask-shaped cross section, and the sipe has an opening width of 1.5 mm and a depth of
Same as Invention Tire 1 except 6.5 mm, bottom diameter 4.0 mm. ○ Comparative tire Except for having the tread pattern shown in FIG. 3, the size and structure are the same as those of the invention tire.

◎ Test method The tire assembled on the rim was filled with the specified internal pressure and mounted on an actual vehicle, and the actual vehicle was run on a test course under a load condition equivalent to two passengers. Highway,
In mode driving assuming urban roads, for each of the front and rear tires after running 10,000 km, visually inspect the wear shape and measure the residual groove depth in the tread central area and side areas to evaluate the drainage performance. Was evaluated by detecting the rate of occurrence of the hydroplaning phenomenon when entering the road surface at a water depth of 10 mm in a straight line.

◎ Test results The results of the above tests are shown in Table 2 with index values. In addition,
The larger the index value, the better the result.

[Table 2] According to Table 2, it is clear that each of the invention tires can effectively prevent the occurrence of shoulder drop wear while ensuring a high drainage property.

[0032]

As is apparent from the above comparative examples, according to the present invention, shoulder drop wear is prevented and uniform wear of the entire tread surface is achieved without impairing drainage. You can

[Brief description of drawings]

FIG. 1 is a tread pattern showing an embodiment of the present invention.

FIG. 2 is a diagram showing a negative rate distribution.

FIG. 3 is a view showing a tread pattern of a comparative tire.

[Explanation of symbols]

 1 tread tread 2 first inclined main groove 2a, 3a central portion 2c, 3b side portion 3 second inclined main groove 4, 5, 7, 8 sipes 4a, 5a, 7a, 8a shoulder auxiliary groove 6 auxiliary groove

Claims (5)

[Claims] 1. A tread tread portion is provided with two kinds of inclined main grooves of a first type and a second type that intersect in a substantially X shape, and these inclined main grooves are made to intersect each other at a plurality of positions.
The angle of each side portion of the inclined main groove with respect to the tire circumferential direction is made larger than that of the central portion thereof, while the angle of each side portion of the second inclined main groove with respect to the tire circumferential direction is set. , It is smaller than that of its central part, and the groove width of the central part is wider than that of the side part in at least one of those inclined main grooves, and the negative ratio of the tread tread is the center of the tread tread. Pneumatic tires that tend to decrease from area to side area. 2. The angle of the first inclined main groove with respect to the tire circumferential direction is set to 0 to 20 ° in the central portion thereof, and
The side portion is 60 to 80 °, and the angle of the second inclined main groove with respect to the tire circumferential direction is 30 to 50 ° in the central portion.
The pneumatic tire according to claim 1, wherein the side portion has an angle of 0 to 15 °. 3. The volume of the tread rubber between the tread center and the position of 1/4 of the tread width from the tread center is 1.3 to 3 between the 1/4 position and the tread edge. The pneumatic tire according to claim 1 or 2, which is 1.6 times as large. 4. The pneumatic tire according to claim 1, wherein a groove width of a central portion of the first inclined main groove is narrower than that of a central portion of the second inclined main groove. 5. The first and second inclined main grooves are terminated in a side area of the tread tread portion, and their respective groove ends are opened to the tread end through a narrow groove. 4. The pneumatic tire according to any one of 4 above.