JPH04193608A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce pattern noise and increase wet and dry performances by specifying an angle of slant grooves at a tread center area relative to a tire equatorial and also an angle of slant grooves at tread side areas relative to the tire equatorial. CONSTITUTION:A land portion 2 extended continuously in the tire circumferential direction is formed at the tread center portion of a tread ground-contact surface portion 1. Then slant grooves 3, separated gradually from each other as these are extended from the underside to the upperside of a tire as viewed from the front when the tire is installed on a vehicle, are formed on both sides of the land portion 2. In this case, the angle of the slant grooves 3 relative to the tire equatorial X-X is set within 10 to 30 deg. relative to a tread center at a tread center area 4 which is within 50 to 90% of a tread width, and within an area of 50 to 90 deg. at tread side areas 5 adjacent to the tread center area 4.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention provides a pneumatic tire, in particular, a vehicle interior layer that greatly reduces pattern noise while ensuring a high level of wet performance and dry performance. This relates to high-performance pneumatic tires that provide comfortable living.

(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 according to target performance. It is common to apply, for example,
When wet performance is important, the groove negative ratio is increased, and when hydroplaning resistance is important, the circumferential groove width is increased, and pattern noise is reduced to improve interior comfort. In order to increase the pitch, it is common practice to reduce the negative ratio of the inclined groove to reduce the pitch noise caused by the impact input during stepping in and kicking out.

(Problem to be solved by the invention) By the way, if we focus on pattern noise, it is
There are two main types of noise: noise caused by pattern pitch components, and high frequency noise around I KHz caused by air column resonance in circumferential straight grooves. However, the latter noise cannot be effectively reduced because the circumferential grooves play an extremely important role in ensuring anti-hydroplaning performance. It was virtually impossible.

In other words, the sound pressure level of air column resonance depends on the groove volume of the circumferential groove, no matter how small the groove volume is, regardless of whether it is a circumferential groove, a straight groove, or a straight groove. First, as long as the odor penetrates from the stepping side to the kicking side, high frequency noise around I KHz will always be generated.Therefore, in order to sufficiently remove that noise, the circumferential groove must be eliminated. Although it becomes necessary to do so, this inevitably results in a significant decrease in hydroplaning resistance.

The present invention advantageously solves the problems of the prior art, and removes circumferential grooves from the tread surface (thereby sufficiently reducing pattern noise, while improving wet performance including hydroplaning resistance). To provide a pneumatic tire that can ensure a high level of dry performance.

(Means for Solving the Problems) The pneumatic tire of the present invention includes a land portion continuous in the tire circumferential direction in the pattern center portion of the tread surface portion, and a land portion of the tire on each side of the land portion. When viewed from the front when mounted on a vehicle, each inclined groove is provided, extending in a direction away from each other from below to above, and opening at the tread edge but not reaching the pattern center. In the central area of the tread, a thin groove is provided that extends across the pattern center in the same direction as each of the inclined grooves and intersects with the inclined grooves. 50-90%
In the central area of the tread, the angle of each inclined groove with respect to the tire equatorial plane is in the range of 10 to 30°, and in the side areas of the tread adjacent to the central area of the tread, the angle of each inclined groove with respect to the tire equatorial plane is in the range of 10 to 30 degrees. The angle with respect to the surface is in the range of 50 to 90 degrees.

More preferably, the pattern center is located within 50% of the tread width around the tread center.

Preferably, 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, and the auxiliary groove is opened at the end of the tread and has one slope. Continue with the groove.

The width of the land portion of the pattern center portion is preferably in the range of 5 to 25% of the tread width, and the angle of the narrow groove with respect to the tire equatorial plane is in the range of 50 to 90 degrees. It is preferable to do so.

Furthermore, in the tread side region, it is preferable that at least one end of the narrow groove is connected with a bent extending portion extending across the inclined groove, and the bent extending portion is connected to the tire equatorial plane. It is preferable that the angle with respect to the surface is in the range of 10 to 30 degrees.

More preferably, the narrow grooves in the tread center region are formed on respective extension lines of the inclined groove portions and the auxiliary grooves extending in the tread side regions, and the bent extension portions are formed in the tread center region. It is formed on the extension line of the existing inclined groove portion.

(Function) In this pneumatic tire, the generation of pattern noise caused by air column resonance can be completely prevented by removing the circumferential grooves that are continuous in the tire circumferential direction from the tread surface. In addition, when the tire is viewed from the front, the sloped grooves that extend away from each other from the bottom to the top can extremely effectively prevent deterioration in wet performance, including anti-hydroplaning performance. I'll come.

By terminating the end of each inclined groove on the pattern center side at a position in front of the pattern center, the center area of the tread, which has a large effect on pattern noise, especially pitch noise caused by impact input, can be , it is possible to form a continuous land segment in the circumferential direction with a center line extending linearly in the circumferential direction of the tire, which can effectively reduce pattern noise. By extending narrow grooves having a groove width such that they touch each other in the central region of the tread across the pattern center in the same direction as the respective inclined grooves and intersecting the inclined grooves, the inclined grooves are formed. By dividing the land portion between the grooves into appropriate dimensions, the ground contact performance of the tire can be greatly improved.

Moreover, in this tire, the angle of each inclined groove with respect to the tire equatorial plane is 10 to 10% in the tread center area within 50 to 90% of the tread width, centered on the tread center.
The 30° range provides excellent drainage,
Provides effective reduction of pattern noise.

In other words, for drainage performance and pattern noise, the influence of the inclined grooves extending in the central area of the tread is dominant, and in the central area or less than 50% of the tread width, the drainage performance is affected by the so-called high-angle inclined grooves. No improvement can be expected, and if it exceeds 90%, sufficient lateral rigidity cannot be imparted to the land area of the tread side area to ensure steering stability on dry road surfaces. Also, if the inclined groove angle with respect to the tire equatorial plane is less than 10°,
It becomes difficult to provide the required rigidity to the land area between adjacent inclined grooves in the circumferential direction, and if it exceeds 30 degrees, it becomes difficult to ensure drainage by quickly discharging water to the front side of the ground contact area. In addition, it becomes difficult to reduce pattern noise.

Furthermore, in this case, by setting the angle of each inclined groove with respect to the tire equatorial plane in the tread side area to be in the range of 50 to 90 degrees, water that has entered into each inclined groove in the tread center area is reduced. This results in rapid lateral ejection of water, and also ensures high lateral rigidity of the land area between the inclined grooves.

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 area will be different from the direction in which they extend in the center area of the tread. The opposite will occur, making smooth drainage impossible.

Preferably, the pattern center is located within 50% of the tread width around the tread center, so that the drainage functions of both inclined grooves located on each side of the pattern center are made sufficiently equal.

In other words, if the pattern center is arranged over 50% of the tread width, the difference between the drainage time by the longer inclined grooves and the drainage time by the shorter inclined grooves becomes too large, making it difficult to drain water quickly. I can't guarantee sex.

Also here, an auxiliary groove is formed in the tread side region that is substantially parallel to a portion of the inclined groove extending to the tread side region, the auxiliary groove is open at the tread end, and the auxiliary groove is formed at one of the tread side regions. If it is continuous with the groove, not only can drainage in the tread side area be made smoother and faster, but also the large part of the tread side area can be divided into two by the auxiliary groove. It is possible to improve uneven wear resistance by removing the extreme rigidity difference between the corners of the area and the corners of the central area.

Furthermore, when the width of the corner of the pattern center portion is set to 5 to 25%, preferably 10 to 20% of the tread width, high wear resistance and excellent handling stability can be achieved under appropriate corner rigidity. In addition, sufficient wet drainage performance can be ensured.

In other words, if the corner width is less than 5% of the tread width, the corner rigidity is insufficient, resulting in decreased wear resistance and steering stability, and if it exceeds 25%, the groove area near the pattern center is insufficient. If it is insufficient, wet performance will deteriorate.

By the way, in the central area of the tread, the angle of the narrow grooves extending across the pattern center with respect to the tire equatorial plane is 50
When the angle is within the range of ~90°, the overall shape of each divided corner is In addition to advantageously increasing the rigidity, the narrow grooves can also effectively contribute to reducing pattern noise.

In other words, if the angle is less than 50°, the angle between the inclined groove and the narrow groove becomes a sharp acute angle, and the wear resistance of each divided corner, especially the acute corner, decreases significantly, and the angle becomes 90°. °
If it exceeds the tire meridian, the narrow grooves will extend in the opposite direction with respect to the tire meridian, and will be oriented in a direction corresponding to the tire's tread contact shape, which will cause an increase in pattern noise.

Furthermore, when the tread side area is wide and a bent extension extending across the inclined groove is connected to at least one end of the narrow groove, the corner rigidity of the tread side area may be reduced. Advantageously, when the angle of the bent extension portion with respect to the tire equatorial plane is set in the range of 10 to 30 degrees, the ground contact performance of the tire can be further improved. It is possible to bring about improvement.

In other words, if the angle is outside the above range, the angle of intersection between the inclined groove and the extended bent portion in the tread side area becomes too acute;
Uneven wear occurs at the sharp corners.

In addition, in the above-mentioned place, the narrow groove is formed on each extension line of the inclined groove part and the auxiliary groove extending in the tread side area, and the bent extension part is formed in the tread central area. When the grooves are formed on the extension line of the inclined groove portion, the shape and the rigidity of each divided corner can be made almost uniform, thereby ensuring uniformity of wear.

(Example) Embodiments 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 is a tread surface, and 2 is formed at a pattern center portion that corresponds to a part of the tread center, and is continuous in the tire circumferential direction. Each corner is shown.

On each side of the corner 2, there are respective inclined grooves 3 extending in a direction away from each other from the bottom to the top, as shown in the figure, when the tire is viewed from the front when the tire is mounted on a vehicle. are formed with a phase shift of approximately half a pitch in the circumferential direction of the tire, and each of these inclined grooves 3 is opened at the tread edge, and at a position in front of the pattern center located overlapping the tire equatorial plane XX. Here, the angle formed by each of these inclined grooves 3 with respect to the tire equatorial plane XX is defined as the tread width, with the tread center overlapping the tire equatorial plane XX and the pattern center as the center. The central tread area within the range of 50 to 90% of 4 to 10
~30° and 5 for each tread side area 5 adjacent to its central tread area 4.
The angle is within the range of 0 to 90 degrees.

Here, then, in each tread side area 5,
An auxiliary groove 6 is formed which extends substantially parallel to the portion of the inclined groove 3 extending in the side region 5 thereof, with one end of the auxiliary groove 6 opening at the tread edge and the other end opening into the tread edge. An opening is made in the middle of the groove 3.

In addition, the tread center area 4 is provided with narrow grooves 7 which are bent at the pattern center and extend in the same direction as the respective inclined grooves 3, and which intersect with the inclined grooves 3. , the dimensions are such that the groove walls contact each other when in contact with the ground, and the angle between them and the tire equatorial plane XX is 50 to 90 on each side of the land portion 2. An angle within the range of °.

Preferably, the narrow grooves 7 are formed here in an extension of the inclined groove portions and the auxiliary grooves 6 extending in the tread side regions.

According to the tire configured in this manner, under the action of the inclined grooves 3 and the auxiliary grooves 6, pattern noise can be effectively reduced as described above, and excellent drainage performance can be provided. Also, under high land stiffness,
It can provide excellent handling stability on dry road surfaces.

By the action of the narrow grooves 7, the ground contact of the tire can be improved, and the overall rigidity of each divided land portion can be advantageously increased, and an increase in pattern noise can be effectively prevented. I can do it.

FIG. 2 shows a tread pattern showing another embodiment of the present invention, in which the inclined grooves 3 located on each side of the land portion 2 are arranged in the same phase with each other in the circumferential direction of the tire. This is what I did.

Since the basic structure of the tire of this example is the same as that shown in FIG. 1, it can provide the same effects as those of the previous embodiment.

FIG. 3 shows that the width of each tread side section 5 is set somewhat wider than that shown in FIG. Bent extension portions 8 that intersect the inclined grooves 3 and the auxiliary grooves 6 and extend in the same direction as the narrow grooves 7 are provided alternately and connected to the respective narrow grooves 7 adjacent to each other in the circumferential direction of the tire. The angle that each bent extension portion 8 makes with respect to the tire equatorial plane XX is lθ~3
More preferably, each bent extension portion 8 extends on an extension line of the inclined groove portion extending in the central region of the tread.

Note that in this example, the narrow groove 7 and the bent extension portion 8 are the inclined groove 3.
It is continuous within the curved part of.

In addition to the above-mentioned effects, the tire in this example is caused to flex, especially under the action of the folded extensions 8 in the tread side areas 5.
This has the advantage of further improving the ground contact.

FIG. 4 shows a tread pattern showing still another embodiment of the present invention, in which the pattern center Y-Y is separated from the tread center overlapping the tire equatorial plane XX.
It is positioned offset to the outside of the tire in the mounting position within 25% of the tread width, and other than this point, it is
This is almost the same as the embodiment shown in the figure.

In addition to the effects of the above-mentioned embodiments, this tire deflection is caused by the fact that the pattern center is located approximately in the center of the ground contact area that moves to the outside of the turn when the vehicle turns, which improves water drainage during the turn. It will be a big improvement.

[Comparative example]

Comparative tests between the invention tire and the conventional tire regarding low pattern noise, anti-hydroplaning performance, and handling stability on dry road surfaces will be described below.

◎Test tire size: 205150 R15 - Invention tire ■ A tire with a tread pattern shown in Figure 1, with a tread width of 184 mm, a negative ratio of 30%, and a tread center area 4 of the inclined groove 3. The angle θ1 of the portion extending to the tire equatorial plane is 18°,
The groove width of that part is 6.5 mm, and the angle θ2 of the part extending to the tread side area 5 with respect to the tire equatorial plane is 6.5 mm.
is 63°, and the groove width at that part is 7.0 mm, and the groove width of the auxiliary groove 6 is 5.5 mm, the groove width of the narrow groove 7 is 0.8 mm, and the narrow groove 7 is The angle θ made with the tire equatorial plane is 63°, the width of the tread center area 4 is 130 mm, and the minimum width t of the ridge 2 is 12
Invented Tire ■ A tire having a tread pattern shown in Fig. 2, in which the minimum width t of the ridge 2 is 8.0 mm, and each inclined groove located across the ridge 2. 3. Same as Invention I tire except that the phases in the tire circumferential direction are aligned. Invention tire ■ A tire having a tread pattern shown in Fig. 3, and the width of the tread center area 4 is 100 mm. At the same time, the tread side area 5 is provided with a bent extension part 8 having an angle of θ4 or 18° with respect to the tire equatorial plane XX, and the groove width of the bent extension part 8 is 0.7 mm, and Slanted groove 3
The invention tire ■ is the same as the invention tire ■, except that the angle θ with respect to the tire equatorial plane A tire having a pattern, which is the same as Invention Tire 1 except that the pattern center is deviated by 30 mm from the tread center to the outside of the tire in the mounting position.Conventional tire having the tread pattern shown in FIG. Tires ◎Test method Each tire was installed on an actual vehicle with 100% internal pressure and load based on JIS standards, and pattern noise was tested on various road surfaces with different surface roughness at 40 km/h ~ 11
The vehicle was driven at a speed of 00 km/h, and the generated pitch noise and high-frequency noise were evaluated comprehensively. Hydroplaning resistance was evaluated by driving straight on a road surface with a water depth of 5 mm and measuring the critical speed at which hydroplaning occurs. However, the anti-hydroplaning performance during turning is evaluated by measuring the limit speed at which hydroplaning occurs when driving around a corner with a water depth of 5 mm and a radius of 100 m, and the handling stability on a dry road surface is evaluated. We performed various types of driving and comprehensively evaluated the driving feeling.

◎Test Results The results of each of the above tests are shown in the table below with index values. Note that the index value is expressed with the conventional tire as 100, and the larger the index value, the better the result.

According to this table, it is clear that all of the invented tires can effectively reduce pattern noise without substantially reducing the hydroplaning resistance performance and the steering stability on dry road surfaces. It is clear that the invention tire (2) can also advantageously improve dry handling.

(Effects of the Invention) As is clear from the above, the present invention can effectively reduce pattern noise and sufficiently improve wet performance and dry performance including hydroplaning resistance. Can it be maintained high?

[Brief explanation of the drawing]

1 to 4 show a tread pattern showing an embodiment of the present invention, and FIG. 5 shows a tread pattern showing a conventional example. ■...Tread tread portion 2...Land portion 3...Slanted groove 4...Tread center area 5...Tread side area 6...Auxiliary groove 7...Slim groove
8... Figure 1 of the bent extension part! 41---Tread central section tA Figure 2 τ Figure 3 Figure 4

Claims (1)

[Claims] 1. A land portion continuous in the circumferential direction of the tire is provided at the pattern center portion of the tread surface, and a land portion is provided on each side of this land portion in a front view when the tire is mounted on a vehicle. , where each inclined groove is provided, extending in a direction away from each other from the bottom to the top, and opening at the tread edge but not reaching the pattern center, the tread width is centered at the tread center. 50-9
In the tread center area within the range of 0%, the angle of each inclined groove with respect to the tire equatorial plane is in the range of 10 to 30°, and in the tread side area adjacent to the tread center area,
A pneumatic tire in which the angle of each inclined groove with respect to the tire's equatorial plane is in the range of 50 to 90 degrees. 2. The pneumatic tire according to claim 1, wherein the tread central region is provided with narrow grooves extending across the pattern center in the same direction as the respective inclined grooves and intersecting the inclined grooves. 3. The pneumatic tire according to claim 1 or 2, wherein the pattern center is located within 50% of the tread width around the tread center. 4. An auxiliary groove is formed in the tread side area that is substantially parallel to a portion of the slanted groove extending to the tread side area, and the auxiliary groove is opened at the end of the tread, and the one slanted groove The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is formed in a continuous manner. 5. The width of the land area at the center of the pattern is 5 times the tread width.
5. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is in the range of 25% to 25%. 6. The angle of the narrow groove with respect to the tire equatorial plane is 50
A pneumatic tire according to any one of claims 1 to 5, which is formed at an angle within the range of -90°. 7. The pneumatic insert according to any one of claims 1 to 6, wherein a bent extension extending across the inclined groove is connected to at least one end of the narrow groove in the tread side region. tire. 8. The pneumatic tire according to claim 7, wherein the angle of the bent extension portion with respect to the tire equatorial plane is in the range of 10 to 30 degrees. 9. The narrow grooves are formed on respective extension lines of the inclined groove portions and the auxiliary grooves extending in the tread side regions, and the bent extension portions are formed on the respective extension lines of the inclined groove portions extending in the tread center region. The pneumatic tire according to claim 7 or 8, which is formed on an extended line.