JPH04218410A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide an excellent dwelling comfortableness in a car cabin and enhance the wetting performance by greatly reducing the pattern noise while a high level drying performance is secured. CONSTITUTION:In the tread 1 of a pneumatic tire concerned, inclined grooves 2 are provided which are located apart about the pattern center in the front view in the attitude mounted to the car, extend in the direction separating apart from each other in the direction from below to above, and open at the tread end but not reach the pattern center, wherein the angle alpha of each groove 2 to the tire equator plane shall range 10-30 deg. in the tread central area to be enlarged out of this extent in the side areas of the tread, and at the end of each inclined groove 2 on the pattern center side, a narrower groove 5 intersecting the inclined groove at an angle beta ranging from 60 to 110 deg. is formed so as to be continuing while extending across the pattern center.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is intended for use in pneumatic tires, in particular, while ensuring a high level of dry performance, greatly reducing pattern noise, and providing excellent interior comfort, and at the same time improving wet performance. also relates to improving high performance pneumatic tires.

0002

[Prior Art] Conventional pneumatic tires of this type are based on a so-called directional pattern, which is a combination of circumferential straight grooves and directional inclined grooves, and various tunings are made to the basic pattern depending on the target performance. For example, when wet performance is emphasized, the groove negative ratio is increased, and when hydroplaning resistance is emphasized, the width of the circumferential groove is widened, and In order to reduce pattern noise and improve cabin comfort, it is common practice to reduce the negative ratio of the inclined grooves to reduce pitch noise caused by impact input when stepping in and kicking off the tire. ing.

0003

[Problems to be Solved by the Invention] If we pay attention to pattern noise, it is noise caused by pattern pitch components and air column resonance of circumferential straight grooves.
There are two types of high-frequency noise, around 1 KHz.The former noise can be reduced by suppressing the impact input component during stepping and kicking, as in the conventional technology, but the latter noise Since the circumferential grooves play an extremely important role in ensuring anti-hydroplaning performance, it has been virtually impossible to reduce them effectively. In other words, the sound pressure level of air column resonance depends on the groove volume of the circumferential groove, but no matter how small the groove volume is, the circumferential groove does not matter whether it is a straight groove or not. First, as long as it penetrates from the stepping side to the kicking side, high frequency noise of around 1KHz will always be generated.Therefore, in order to sufficiently remove that noise, it is necessary to eliminate the circumferential groove. Although it is necessary, if the circumferential groove is eliminated without any measures, the hydroplaning resistance performance will inevitably deteriorate significantly. The present invention advantageously solves the problems of the prior art, and effectively reduces the pattern noise by removing the circumferential groove from the tread surface to effectively prevent the generation of high frequency noise. The present invention provides a pneumatic tire that can ensure high levels of wet performance and dry performance, including hydroplaning resistance.

0004

[Means for Solving the Problems] The pneumatic tire of the present invention has a tread surface of the tire, which is positioned across the pattern center from the bottom to the top when viewed from the front when mounted on a vehicle. Each slanted groove extends in a direction away from the other and opens at each tread end but does not reach the pattern center. In the central area of the tread within 50-90% of the width, the angle ranges from 10 to 30°, and in the side areas of the tread, the angle is greater, also for example from 50 to 90°.
, and the end of each of these inclined grooves on the pattern center side is provided with a continuous narrow groove that extends across the pattern center and has an angle of intersection with the inclined groove of 60 to 110°. It was formed by Here, the groove width of the narrow groove is usually in the range of 10 to 30% of the groove width of the inclined groove. Preferably, the distance in the tread width direction of each of the inclined grooves located across the pattern center is in the range of 3 to 8% of the tread width, and more preferably, the inclined groove extends to the tread side area. An auxiliary groove is formed in the tread side region that is substantially parallel to the tread, with one end of the auxiliary groove opening into the tread edge and the other end of the auxiliary groove opening into the sloping groove.

[0005]

[Function] In this pneumatic tire, by removing the circumferential grooves that are continuous in the tire circumferential direction from the tread surface, it is possible to completely prevent the generation of high frequency noise caused by air column resonance. When the tire is viewed from the front, it is possible to extremely effectively prevent the deterioration of wet performance, including hydroplaning resistance, by the action of the inclined grooves at appropriate pitches, which extend away from each other from the bottom to the top. .

[0006] By terminating the end of each inclined groove on the pattern center side at a position in front of the pattern center, the pattern center portion becomes a substantially continuous land portion, and impact noise is reduced due to smooth grounding. In addition, in the central area of the tread, narrow grooves are provided that have a groove width that is such that the groove walls do not contact each other even under ground contact conditions.
By connecting each inclined groove across the pattern center, the land area between the inclined grooves can be divided into appropriate dimensions, greatly improving the tire's ground contact performance. The grooves can also effectively contribute to improving wet performance without generating large pitch noise.

Moreover, in this tire, the angle of each inclined groove opened at the tread end with respect to the tire equatorial plane is in the range of 10 to 30 degrees in the tread center area, thereby achieving excellent drainage performance and effective pattern noise reduction. resulting in significant reductions. In other words, if the inclined groove angle with respect to the tire equatorial plane is less than 10°, it is difficult to provide the required rigidity to the land portion between circumferentially adjacent inclined grooves under a certain pitch of the inclined grooves. If it exceeds 30 degrees, it becomes difficult to ensure quick drainage to the front side of the ground contact part, and it becomes difficult to reduce pattern noise.

[0008] Also, here, the angle of each inclined groove with respect to the tire equatorial plane in the tread side region is larger than that in the tread center region, preferably in the range of 50 to 90°, so that the angle in the tread center region is increased. Water that has entered each inclined groove is quickly discharged to the side of the tire, and at the same time, high lateral rigidity of the land area between the inclined grooves is ensured. If the angle is less than 50 degrees, the rigidity of the land portion will be insufficient, and if it exceeds 90 degrees, the direction in which the inclined grooves extend in the tread side region will be different from the direction in which they extend in the center region of the tread. will be reversed, making it impossible to drain water smoothly.

In addition, in this tire, by setting the intersection angle between the narrow groove and the inclined groove to be in the range of 60 to 110 degrees, it is possible to effectively prevent a decrease in uneven wear resistance of the divided land portions partitioned by the narrow groove. In addition, drainage performance by the narrow groove itself is ensured without increasing pattern noise. That is,
When the intersection angle is less than 60°, the angle of the narrow groove with respect to the tire equatorial plane becomes similar to that of the inclined groove,
Because the intersection angle between both grooves is too acute, uneven wear of the land between the inclined grooves, which is divided by the narrow groove, becomes severe. Conversely, when the intersection angle exceeds 110 degrees, the extension of the narrow groove becomes severe. Since the direction approaches the ground contact ring line of the tire, not only drainage performance decreases but also pitch noise increases.

Preferably, the distance in the tread width direction of each of the inclined grooves located across the pattern center and ending without reaching the pattern center is set to 3 of the tread width.
By setting it in the range of ~8%, it is possible to exhibit high wear resistance and excellent handling stability under appropriate rigidity of the pattern center part, and also ensure sufficient wet drainage performance. can. In other words, if it is less than 3%, the rigidity of the pattern center part is insufficient,
Wear resistance and handling stability decrease, and if it exceeds 8%,
The groove negative ratio at the pattern center is insufficient, resulting in poor wet drainage.

[0011] Also preferably, an auxiliary groove is formed in the tread side region which is substantially parallel to the portion of the inclined groove extending in the tread side region, and the auxiliary groove is formed at the end of the tread and at the end of the inclined groove. By having openings in each area, drainage in the tread side area can be made smoother and faster, and the large land area between the inclined grooves in the tread side area can be divided into two, allowing the tread to be opened. It is possible to eliminate the extreme difference in rigidity between the land portions of the side areas and the land areas of the central area, and improve uneven wear resistance.Especially regarding drainage, the auxiliary grooves are placed on the extension line of the narrow grooves. It is even more effective when formed. In this way, this tire not only ensures sufficient dry performance, in other words, steering stability on dry roads and wet drainage performance, but also effectively reduces pattern noise and greatly improves cabin comfort. can be done.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows a tread pattern showing an embodiment of the present invention. In the figure, 1 indicates a tread surface portion, and 2 indicates a tread surface portion 1 formed on each side of the pattern center. In a front view of the mounting position, inclined grooves extending in directions away from each other from the bottom to the top are shown. Note that the internal reinforcing structure of the tire is the same as that of a general radial tire, so illustration thereof is omitted. Here, the respective inclined grooves 2 located apart from the pattern center which coincides with the tire equatorial plane Preferably, the upper end of each inclined groove 2 opens at the tread edge, while each lower end ends at a position in front of the pattern center, and the angle α of each inclined groove 3 with respect to the tire equatorial plane XX is preferably 50-90% of the tread width, centering on the tread center
in the tread central area 3 within the range of 10 to 30°, and in each tread side area 4 adjacent to the tread central area 3 an angle greater than that angle, preferably in the range of 50 to 90°. The angle is within. Here, when the tread center area 3 is less than 50% of the tread width, it is not possible to expect much improvement in drainage performance by the inclined grooves 2, and when it exceeds 90%, the tread side area 4 is It becomes difficult to provide sufficient lateral rigidity to ensure steering stability on dry road surfaces.

[0013] Also here, in the central region of the tread, at the end of each inclined groove 2 facing the pattern center, extending across the pattern center, it also includes:
Each of the narrow grooves 5 extending from the bottom to the top at a distance from each other is continuously formed, and each of these narrow grooves 5 is
The intersecting angle β with respect to the inclined groove 2 is within the range of 60 to 110°. For example, such a narrow groove 5, which can have a groove width of 1 to 3 mm, extends across one inclined groove 2 from the pattern center side to the tread edge side and forms a second inclined groove. It opens into groove 2. Therefore, this narrow groove 5 can function not only to improve the ground contact properties of the tread central region 3 but also to improve wet drainage properties.

More preferably, the distance t in the tread width direction of each of the inclined grooves 2 located apart from the pattern center is set to a value within the range of 3 to 8% of the tread width. In the tread side region 4, an auxiliary groove 6 is formed which extends substantially parallel to the part of the inclined groove 2 extending into that side region 4, with one end of this auxiliary groove 6 at the tread end and the other end at the tread end. Each of the inclined grooves 2 is opened. Here, more preferably, by forming the auxiliary groove 6 on the extension line of the narrow width groove 5 as shown in the figure,
Water is discharged through the narrow groove 5 more smoothly and quickly. According to the tire configured in this way, the above-mentioned effects can be brought about in terms of wet drainage performance, dry performance, and pattern noise.

FIG. 2 shows, in addition to what has been described with reference to FIG. , the end of each sipe 7 on the pattern center side is opened at the lower end of the inclined groove 2, and the end on the tread end side is opened at the widening bent portion of the inclined groove 2. The sipes 7 here have a groove width such that the groove walls contact each other when the tire is in contact with the ground, and particularly function to further improve the ground contact performance in the tread center area 3.

[0016]

[Comparative Example] Comparative tests between the invention tire and the conventional tire regarding the steering stability on dry road surfaces, wet drainage performance, and low pattern noise will be explained below. ◎Tire with test tire size 205/60 R15/Invention Tire I A tire having a tread pattern shown in FIG. 1,
The groove width of the inclined groove 2 is 6.3 mm in the tread center area,
The width of the narrow groove 5 is 7.0 mm in the tread side area, and the angle of the inclined groove 2 with respect to the tire equatorial plane XX is 18° in the tread center area and 63° in the tread side area. The width is 2.0 mm, the intersection angle β with the inclined groove 2 is 81°, the groove width of the auxiliary groove 6 is 5.5 mm, and the distance between the inclined grooves 2 located across the pattern center is 8.0 mm (tread 5% of the width) - Invention Tire II A tire having a tread pattern shown in Fig. 2,
A tire with the same dimensions as the invention tire I, except that the groove width of Sipe 7 was 0.7 mm. - Conventional tire. A tire with a tread pattern shown in Figure 3. - Test method: A tire filled with the normal internal pressure according to JIS standards was tested on an actual vehicle. The handling stability on dry roads was evaluated based on the overall feeling of the test driver during various runs on a dry circuit, and the wet drainage performance was evaluated under load conditions with two passengers. was evaluated by measuring the vehicle speed at which the hydroplaning phenomenon occurs when driving straight on a wet road surface with a water depth of 5 mm, and the low pattern noise was evaluated based on the feeling of interior noise when driving on a smooth road surface at 100 to 40 km/h. It was evaluated using ◎Test results These test results are shown in the table below using indexes. Note that the index value is expressed with the test result of the conventional tire set as 100, and the larger the index value, the better the result.

[0017]

[Table 1] According to this table, it is clear that all of the invented tires can effectively reduce pattern noise and improve wet drainage performance while fully demonstrating steering stability. It is.

[0018]

Therefore, according to the present invention, as is clear from the foregoing, pattern noise can be effectively reduced, and both wet performance and dry performance can be maintained sufficiently high.

[Brief explanation of the drawing]

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

FIG. 2 is a tread pattern showing another embodiment of the invention.

FIG. 3 is a tread pattern showing a conventional example.

[Explanation of symbols]

1 Tread surface 2 Slanted groove 3 Tread central area 4 Tread side area 5 Narrow groove 6 Auxiliary groove 7 Sipe

Claims (3)

[Claims] [Claim 1] A tread edge, which is located on the tread surface portion and is located across the pattern center and extends in a direction away from each other from below to above, when viewed from the front when the tire is mounted on a vehicle. Each of the inclined grooves is provided with an opening in the tread but does not reach the pattern center, and the angle with respect to the tire equatorial plane is in the range of 10 to 30 degrees in the central area of the tread, and the angle is larger in the side areas of the tread. , a continuous narrow groove is formed at the end of each of these inclined grooves on the pattern center side, extending across the pattern center and having an angle of intersection with the inclined groove in a range of 60 to 110°. A pneumatic tire. 2. The pneumatic tire according to claim 1, wherein the distance in the tread width direction between the respective inclined grooves located apart from the pattern center is in the range of 3 to 8% of the tread width. 3. An auxiliary groove is formed in the tread side region that is substantially parallel to the portion of the inclined groove extending in the tread side region, one end of the auxiliary groove being at the tread end and the other end being at the tread end. The pneumatic tire according to claim 1 or 2, wherein each of the inclined grooves is opened.