JP2975124B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, in particular, to provide a high level of dry performance, greatly reduce pattern noise, and provide excellent vehicle interior comfort. The invention also relates to a high performance pneumatic tire which is also improved.

[0002]

2. Description of the Related Art A conventional pneumatic tire of this type is based on a so-called directional pattern formed by combining a circumferential linear groove and a directional inclined groove, and various tunings are made to the basic pattern according to target performance. In general, for example, when wet performance is emphasized, the groove negative ratio is increased, and when importance is placed on hydroplaning resistance, the groove width of the circumferential groove is increased.
When reducing the pattern noise to enhance the cabin comfort, it is widely practiced to reduce the negative ratio of the inclined groove to reduce the pitch noise caused by the impact input when the tire is stepped on or kicked out. ing.

[0003]

Here, if attention is paid to pattern noise, it can be attributed to noise caused by the pattern pitch component and air column resonance of the circumferential straight groove.
High-frequency noise of about 1 kHz is roughly classified into two types. The former noise can be reduced by suppressing the impact input component at the time of stepping and kicking as in the prior art, but the latter noise can be reduced. However, it was practically impossible to effectively reduce the diameter of the groove because the circumferential groove played an extremely large role in securing the hydroplaning resistance. In other words, the sound pressure level of the air column resonance depends on the groove volume of the circumferential groove, but no matter how small the groove volume, the circumferential groove may or may not be a straight groove. However, as long as it penetrates from the stepping side to the kicking side, high-frequency noise of about 1 KHz is always generated. Therefore, in order to sufficiently remove the noise, it is necessary to eliminate the circumferential groove. Although it becomes necessary, if the circumferential grooves are eliminated without any measures, the hydroplaning resistance performance will be remarkably reduced. The present invention advantageously solves such a problem of the prior art, and sufficiently reduces pattern noise by removing a circumferential groove from a tread tread portion to effectively prevent occurrence of high-frequency noise. An object of the present invention is to provide a pneumatic tire capable of ensuring high levels of wet performance and dry performance including hydroplaning resistance.

[0004]

According to the pneumatic tire of the present invention, when viewed from the front of the mounting posture of the tire on the vehicle on the tread tread portion, the tire is positioned above the pattern center and mutually upward from below. Extending in the direction of separation, each tread end is provided with an inclined groove that is open at each tread end but does not reach the pattern center. 10 in the central area of the tread within the range of 50-90% of the width
In the tread side area, the angle is larger than that angle, for example, also in the range of 50 to 90 °, and the pattern center is formed at the end of each inclined groove on the pattern center side. It is formed by continuously forming narrow grooves extending transversely and having an angle of intersection with the inclined grooves in the range of 60 to 110 °. Here, the groove width of the narrow groove is
Usually, it is in the range of 10 to 30% of the groove width of the inclined groove. Also preferably, the distance in the tread width direction between each of the inclined grooves located at a distance from the pattern center is set to 3 to 3 times the tread width.
In the range of 8%, and more preferably
An auxiliary groove substantially parallel to the portion extending to the tread side area is formed in the tread side area, and one end of the auxiliary groove is opened to the tread end and the other end is opened to the inclined groove.

[0005]

In this pneumatic tire, the generation of high frequency noise due to air column resonance can be completely prevented by removing the circumferential groove continuous in the tire circumferential direction from the tread tread portion. By the action of each inclined groove having an appropriate pitch extending in a direction away from each other upward from below in the front view of the tire, it is possible to extremely effectively prevent a decrease in wet performance including hydroplaning resistance performance. .

Here, 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 becomes a substantially continuous land, and the impact noise due to smooth grounding. Can be reduced, and a narrow groove having a groove width such that the groove walls do not contact each other even under a ground contact state is formed in the tread central area,
By continuation of each inclined groove across the pattern center, the land section defined between the inclined grooves can be divided into appropriate dimensions to greatly improve the tire's ground contact performance, and at the same time, its narrow width The grooves can effectively contribute to the improvement of wet performance without generating large pitch noise.

Moreover, in this tire, the angle of each inclined groove opening at the tread end with respect to the tire equatorial plane is set in the range of 10 to 30 ° in the central area of the tread, so that excellent drainage and effective pattern noise can be obtained. And reduction. That is, the inclined groove angle with respect to the tire equatorial plane is 10 °
If the angle is less than the predetermined pitch of the inclined grooves, it is difficult to impart the required rigidity to the land between the inclined grooves adjacent in the circumferential direction. It is difficult to ensure quick drainage to the front side of the part, and it is also difficult to reduce pattern noise.

Here, in the tread side area, the angle of each inclined groove with respect to the tire equatorial plane is set to be larger than that in the tread center area, preferably in the range of 50 to 90 °, so that the tread center area is formed. This provides a rapid lateral drainage of the water that has entered into each of the inclined grooves, while ensuring high lateral rigidity of the land between the inclined grooves. If the angle is less than 50 °, the rigidity of the land portion will be insufficient, and if it exceeds 90 °, the extending direction of the inclined groove in the tread side area will be the same as that in the tread central area. Is reversed, and it becomes impossible to perform smooth drainage.

In addition, in this tire, by setting the intersection angle between the narrow groove and the inclined groove in the range of 60 to 110 °, it is possible to effectively reduce the uneven wear resistance of the divided land portions defined by the narrow groove. And the drainage by the narrow groove itself is ensured without increasing the 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 is similar to that of the inclined groove, and the intersection angle of both grooves becomes too acute, so that the groove is divided by the narrow groove. , Uneven wear of the land between the inclined grooves becomes severe, and conversely, the intersection angle is 110 °
When the distance exceeds, the extending direction of the narrow groove approaches the ground contact line of the tire, so that the drainage property is reduced and the pitch noise is increased.

[0010] Preferably, the separation distance in the tread width direction of each inclined groove which is located across the pattern center and ends without reaching the pattern center is set at 3 of the tread width.
By setting the range to ８8%, high wear resistance and excellent steering stability can be exhibited under appropriate rigidity of the pattern center portion, and sufficient wet drainage can be ensured. it can. In other words, if it is less than 3%, the rigidity of the pattern center part is insufficient,
When the wear resistance and steering stability decrease, and when it exceeds 8%,
The groove negative ratio of the pattern center portion is insufficient, and the wet drainage property is reduced.

Preferably, an auxiliary groove substantially parallel to a portion of the inclined groove extending in the tread side area is formed in the tread side area, and the auxiliary groove is formed at the tread end and the inclined groove. By opening each of them, drainage in the tread side area can be made smoother and quicker.In addition, the large land part existing between the inclined grooves in the tread side area is divided into two parts by the tread, The extreme rigidity difference between the land area in the side area and the land area in the central area can be removed, and uneven wear resistance can be improved.In particular, with regard to drainage, the auxiliary groove is placed on the extension of the narrow groove. When formed, it is even more effective. Thus, according to this tire, dry performance, in other words, steering stability and wet drainage on dry road surfaces can be sufficiently ensured, and pattern noise is effectively reduced to improve interior comfort. Can be done.

[0012]

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. In the figure, reference numeral 1 denotes a tread tread portion, and 2 denotes a tread tread portion 1 formed on each side of a pattern center. Each of the inclined grooves extends in a direction away from each other from below to above when viewed from the front in the mounting posture. The internal reinforcing structure of the tire is the same as that of a general radial tire, so that the illustration is omitted. Here, the respective inclined grooves 2 located at a distance from the tire equatorial plane XX and the pattern center coinciding with the tread center are formed so as to be out of phase by approximately a half pitch in the tire circumferential direction. 2 is opened at the tread end, while each lower end is terminated at a position before the pattern center, and the angle α of each such inclined groove 3 with respect to the tire equatorial plane XX is preferably
50% to 90% of the tread width, centered on the tread center
And at each tread side section 4 adjacent to the tread central section 3 the angle is greater than that angle, preferably 50 to 90 degrees. Angle. Here, when the tread central section 3 is set to less than 50% of the tread width,
The improvement of drainage performance by the inclined groove 2 cannot be expected so much, and if it exceeds 90%, the tread side area 4
It is difficult to provide the land portion with sufficient lateral rigidity to secure the steering stability on a dry road surface.

Here, in the central area of the tread, the end of each inclined groove 2 on the pattern center side extends across the pattern center.
The narrow grooves 5 extending from the lower side to the upper side and separated from each other are continuously formed.
The intersection angle β with the inclined groove 2 is set to an angle in the range of 60 to 110 °. For example, in the illustrated example, such a narrow groove 5 that can have a groove width of 1 to 3 mm extends across one inclined groove 2 from the pattern center side to the tread end side to form a second inclined groove 5. Open in groove 2. Therefore, this narrow groove 5 is
In addition to improving the grounding of the tread central area 3,
It can function to improve wet drainage.

[0014] More preferably, the separation distance t in the tread width direction of each inclined groove 2 located across the pattern center is set to a value within the range of 3 to 8% of the tread width. Tread side area 4
Thus, an auxiliary groove 6 extending substantially parallel to a portion of the inclined groove 2 extending to the side area 4 is formed. One end of the auxiliary groove 6 is connected to the tread end and the other end is connected to the inclined groove 2. Open each. In this case, more preferably, the auxiliary groove 6 is formed on an extension of the narrow groove 5 as shown in the figure, so that the discharge of water through the narrow groove 5 is smoother and quicker. According to the tire configured as above,
For each of the wet drainage performance, the dry performance, and the pattern noise, the above-described effects can be obtained.

FIG. 2 shows, in addition to that described with reference to FIG. 1, on each side of the pattern center, a sipe 7 extending parallel to the narrow grooves 5 is formed at the center of the two narrow grooves 5. The end of each sipe 7 on the pattern center side is inclined groove 2
At the lower end of the tread and the end on the tread end side,
Are respectively opened at the widened bent portions. The sipe 7 has a groove width such that the groove walls are in contact with each other when the tire is in contact with the ground. In particular, the sipe 7 functions to further improve the contact property in the tread central section 3.

[0016]

[Comparative Examples] The following describes comparative tests between the inventive tire and the conventional tire on the steering stability on dry road surfaces, wet drainage performance, and low pattern noise. ◎ Test tire 205/60 R15 tire ・ Invention tire I A tire having a tread pattern shown in FIG.
The groove width of the inclined groove 2 is 6.3 mm in the center area of the tread and 7.0 mm in the tread side area, and the width of the inclined groove 2 is
The angle with respect to the tire equatorial plane XX is 18 ° in the tread central area, 63 ° in the tread side area, the groove width of the narrow groove 5 is 2.0 mm, and the intersection angle β between the narrow groove 5 and the inclined groove 2 is 81 °. Groove 6
Groove width is 5.5mm, and the separation distance of each inclined groove 2 located across the pattern center is 8.0mm (tread width 5mm).
Inventive tire II A tire having the tread pattern shown in FIG.
A tire having the same dimensions as the inventive tire I except that the groove width of the sipe 7 is 0.7 mm.-Conventional tire A tire having a tread pattern shown in Fig. 3 ◎ Test method A tire filled with a normal internal pressure according to JIS standards is used in an actual vehicle. Under the load conditions with two occupants, the steering stability on dry road surfaces was evaluated based on the overall feeling of the test driver when performing various runs on a dry circuit. The vehicle speed of the hydroplaning phenomenon when traveling straight on a wet road surface with a depth of 5 mm is measured and evaluated. The low pattern noise is obtained by feeling the vehicle interior noise when traveling on a smooth road surface at 100 to 40 km / h. evaluated. ◎ Test results These test results are indicated with indices in the following table. The index value represents the test result of the conventional tire as 100, and the larger the index value, the better the result.

[0017]

[Table 1] According to this table, it is clear that any of the inventive tires can sufficiently exhibit steering stability, can effectively reduce pattern noise, and can also improve wet drainage.

[0018]

Thus, according to the present invention, as apparent from the above description, the pattern noise can be effectively reduced, and the wet performance and the dry performance can be maintained at sufficiently high levels.

[Brief description of the drawings]

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

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

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

[Explanation of symbols]

 Reference Signs List 1 tread tread portion 2 inclined groove 3 tread central area 4 tread side area 5 narrow groove 6 auxiliary groove 7 sipes

Claims (3)

(57) [Claims] 1. A tread end portion which is located on a tread tread portion with a pattern center therebetween in a front view of a mounting posture of a tire on a vehicle, and extends in a direction away from each other upward from below, and The tread is provided with an inclined groove that opens but does not reach the pattern center. At the end of each of the inclined grooves on the pattern center side, extending across the pattern center, the intersection angle with the inclined groove is
A pneumatic tire formed by continuously forming narrow grooves having an angle in the range of 60 to 110 °. 2. The pneumatic tire according to claim 1, wherein the separation 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. 3. An auxiliary groove substantially parallel to a portion of the inclined groove extending in the tread side area is formed in the tread side area, and one end of the auxiliary groove is provided at the tread end and the other end is provided at the other end. The pneumatic tire according to claim 1 or 2, wherein each of the inclined grooves is opened.