JPH10324116A - Pneumatic tire having steering stability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve steering stability on a wet road. SOLUTION: This tire has two kinds of slant grooves 1, 2, 3, 4 extending in the direction expanding from the lower side toward the upper side when viewed from the front side of the tire, the slightly slant grooves 1, 2 being formed at 45 to 80 degree to the peripheral direction of the tire and the greatly slant grooves 3, 4 at 5 to 30 degree. The two kinds of slant grooves cross each other at an angle of more than 30 degree. The greatly slant grooves 3, 4 extend from the center of pattern to the end of tread in the width of more than 80% of the width of the tread adhering to the ground. The pitch of the slightly slant grooves 1, 2 in the peripheral direction of the tire is 1.8 to 2.2% of the peripheral length of the tire and the pitch of the greatly slant grooves 3, 4 is 3. 6 to 4.4% of the peripheral length of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sports car,
The present invention relates to a pneumatic tire which is applied to a high-output vehicle such as a racing car and exhibits excellent wet drainage performance and has excellent steering stability.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional tire applied to a high-power vehicle such as a sports car or a racing car. FIG. 2A shows a front tire and FIG.
(B) shows a rear wheel tire.

Here, a plurality of circumferential main grooves 21 extending linearly in the circumferential direction of the tire, particularly contributing to the improvement of wet drainage performance, are provided on the tread tread portion. The inclined main groove 2 which obliquely intersects the groove 21 and contributes to the lateral drainage function and the display of the edge effect.
2 is formed in a zigzag shape with the full width of the tread, and
Extending between the two inclined main grooves substantially parallel to them,
An inclined auxiliary groove 23 is provided which functions to control block rigidity which affects the contact property and road surface grip force.

However, even with a tire having such a tread pattern, it is difficult to ensure sufficient wet drainage performance when the vehicle is running at a high speed.
In recent years, with the aim of further improving wet drainage performance,
Various so-called directional patterns, in which a directional inclined groove is combined with a circumferential linear groove, have been proposed.

However, in such a proposed technique,
When the angle of the directional inclined groove with respect to the tire circumferential direction is set to 45 ° or less in order to enhance wet drainage performance, the edge in the tire rotation direction is used for sports cars and racing cars having large horsepower. The effect is reduced and the required traction performance cannot be obtained. On the other hand, when the angle with respect to the tire circumferential direction is set to a value exceeding 45 °, sufficient traction performance can be obtained. There was a disadvantage that the drainage performance could not be provided.

[0006] Therefore, the applicant has first disclosed in Japanese Patent Application Laid-Open No. 8-25991.
As No. 6, a high performance pneumatic tire having the following configuration was proposed. As shown in a development view of the tread pattern in FIG. 3, the tire continuously extends from the lower side to the upper side in the direction in which the tire is mounted on the tread tread portion in a front view of the mounting posture of the tire. Two kinds of inclined grooves 1,2,2
3 and 4 are respectively provided, the gentle inclined grooves 1 and 2 are formed at an angle in the range of 45 to 80 ° with respect to the tire circumferential direction, and the steeply inclined grooves 3 and 4 are formed with 5 to 30 with respect to the tire circumferential direction. At an angle in the range of .degree., Each of them is formed substantially linearly, the intersection angle .alpha. On the acute angle side of the two inclined grooves 1, 2, 3, 4 is set to 30.degree. 2 are extended from the pattern center portion, and the steeply inclined grooves 3 and 4 are
The steeply inclined grooves 3 and 4 are further formed from the pattern center portion toward the tread end side by the tread contact width TW.
And extends over a width WH of 80% or more of
The arrangement pitch Pa of the steeply inclined grooves 3 and 4 in the tire circumferential direction.
Is approximately twice that of the gentle slope grooves 1 and 2, and the groove width of the steep slope grooves 3 and 4 is equal to or larger than that of the gentle slope grooves 1 and 2.

[0007] According to the tire configured as described above, it can be applied to a high-output vehicle such as a sports car or a racing car to provide excellent steering stability and traction performance. The wet drainage performance can be greatly improved both in turning and turning.

[0008]

SUMMARY OF THE INVENTION According to the present invention, the steering stability on a wet road surface is further improved by selecting a specific numerical value in the pneumatic tire previously proposed by the applicant. In particular, it greatly improves the handling stability at relatively low temperatures, and at the same time, sharply changes the stability during turning, in other words, the road surface grip force, due to the change in slip angle. An object of the present invention is to provide a pneumatic tire which is effectively prevented and has excellent steering stability.

[0009]

SUMMARY OF THE INVENTION The pneumatic tire of the present invention, which is excellent in steering stability, is particularly a high-performance pneumatic tire proposed by the applicant in which the pitch of each of the gentle and steep inclined grooves is reduced. More appropriately selected,
The feature of this is that the pitch of the gentle inclined grooves in the tire circumferential direction is 1.8 to 2.2% of the tire circumferential length, and the pitch of the steeply inclined grooves in the tire circumferential direction is the tire circumferential length. 3.6
４4.4%.

In this pneumatic tire, the arrangement stability of each inclined groove with respect to the tire circumference is specified numerically in a specific and particularly preferable range, so that the steering stability on a wet road surface is improved. The road surface temperature can be remarkably improved at a temperature of 15 ° C. or more, particularly at a temperature of less than 15 ° C. Also, the stability during turning on a wet road surface is greatly improved, and a change in slip angle is caused. A change in stability can be effectively suppressed. By the way, it is possible to increase the steering stability performance in actual vehicle running, especially at low temperatures, to 106 to 107% as compared with the tire of Comparative Example 1 in Table 1 to be described later.

In this tire, preferably, the ratio of the groove width of the gentle slope groove to the groove width of the steep slope groove is 50 to 100%.
And According to this, extremely excellent drainage performance can be ensured on a relatively deep water road surface up to about 3 mm.

Preferably, a standard rim (JATMA) is used.
YEAR BOOK 1996), and the negative rate on the ground contact surface under application of an internal pressure of 2.0 kgf / cm ² and a load of 350 kgf is 25 to 45%, particularly 30 to 40%, and more preferably, The groove width of the steeply inclined groove measured in the tread width direction is 3 to 8% of the contact width under the above conditions.

Here, the reason why the negative rate is set to 25 to 45% is that, under a normal wet condition, the negative rate is about 45%, and not only excellent drainage performance but also sufficient block rigidity and sufficient driver filling are ensured. In light rain conditions where drainage is not necessary, the negative rate can be reduced to about 25%.
This is because it is preferable from the viewpoint of steering stability and the like. Also, in the latter, regardless of whether the steeply inclined groove extends in the tire circumferential direction, the drainage performance is still sufficiently ensured,
It is possible to sufficiently prevent the rigidity of the land section defined by each inclined groove from being excessively reduced. Here, more preferably, the negative rate is set to 30 to 40%, whereby the steering stability performance, particularly, the steering stability performance at low temperatures is further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a development view of a tread pattern showing one embodiment of the present invention. The internal reinforcement structure of the tire is the same as that of a general radial tire, and is not shown. In the figure, components similar to those described in FIG. 3 are denoted by the same reference numerals.

As shown in the figure, in the front view of a tire in a mounting posture to a vehicle, two kinds of gentle and gentle inclined grooves 1, 2 and 3 are bordered by a pattern center X ₀ -X ₀ located on a tread center. , 4 are provided so as to be substantially linearly continuous in a direction in which they are mutually expanded from below to above. Here, each of the gentle inclined grooves 1 and 2 is made continuous with each other on the pattern center to form a pair of gentle inclined grooves 1 and 2 in a substantially V-shape.
Each of the gently inclined grooves 1 and 2 extending across the tread 4 is opened to the tread edge every other outside the tread width direction, and the remaining gently inclined grooves 1 and 2 are sharply formed in the vicinity of the tread edge. An opening is made in the inclined grooves 3 and 4, and the processing is completed there.
Here, it is also possible to end all the gentle slope grooves 1 and 2 at the open ends to the steep slope grooves 3 and 4 located closest to the tread end.

[0016] Each of the gently slant groove 2 extending in this manner, the angle phi ₀ with respect to the tire circumferential direction, phi ₁ together, 45 to 80 °, preferably in the range of 55 to 70 °. By the way, the angles φ ₀ and φ ₁ in the case where the gentle slope grooves 1 and 2 are arc-shaped curves having a large radius of curvature are in the ground plane, and extend from the end on the pattern center side to the extending direction of the gentle slope groove. Measure, at a distance of 80% of the total length of the gentle slope groove,
An angle of a straight line connecting the one end and the other end to the tire circumferential direction.

Also, here, the pattern center X ₀ -X ₀
Steeply inclined grooves 3 and 4 extending substantially linearly and separated from each other
Are arranged with a phase shift of half a pitch in the tire circumferential direction, and on the pattern center side, they reach the pattern center X ₀ -X ₀ together and are terminated.
On the tread end side, the openings are formed in sub-inclined grooves 5 and 6 which are formed substantially parallel to the gentle inclined grooves 1 and 2 and extend beyond the tread end, and are terminated.

In addition, the angles θ ₀ and θ ₁ of the steep grooves 3 and 4 with respect to the circumferential direction of the tire are respectively in the range of 5 to 30 °, preferably 10 to 25 ° here. The angle of intersection between the inclined grooves 1 and 2 and the steeply inclined grooves 3 and 4 on the acute angle side is set to 30 ° or more, preferably 30 to 60 °.

Here, the steeply inclined grooves 3, 4 have a radius of curvature.
Angle θ for large curved shapes ₀, Θ₁Is a gentle slope
It is possible to obtain the grooves 1 and 2 in the same manner as described above.
it can.

Further, in this tire, the steeply inclined grooves 3, 4
The tread width TH in the tread width direction.
80% or more of W and steeply inclined grooves 3,
4, the arrangement pitch Pa in the tire circumferential direction is set in a range of 3.6 to 4.4% of the tire circumference, and the same arrangement pitch Pb of the gentle slope grooves 1 and 2 is set to the tire circumference. 1.8 to 2.2
%.

Preferably, the gently inclined grooves 1 and 2, which particularly contribute to the traction performance, the braking control performance, etc.
Is set in the range of 50 to 100% with respect to those of the steeply inclined grooves 3 and 4, which greatly contribute to exhibiting drainage performance.

In the tire as described above, more preferably, the tire is assembled on a standard rim and the internal pressure is 2.0 kg.
f / cm ² , a negative rate of 25 to 45% under the application of a load of 350 kgf ensures excellent drainage performance regardless of the amount of road surface water while ensuring excellent steering stability. Can be. That is, if it is less than 25%, drainage capacity may be insufficient, while if it exceeds 45%, it may be difficult to secure required block rigidity. Here, the negative rate under specific conditions is defined in consideration of the application state of the tire to an actual vehicle.

Also, preferably, the steeply inclined grooves 3, 4
The groove width measured in the tread width direction is set to a range of 3 to 8% with respect to the contact width under the above-described conditions. Effectively suppress the decrease in land rigidity.

That is, if the groove width is less than 3%, it becomes difficult to secure drainage performance. If the groove width is more than 8%,
The rigidity of the land portion becomes too low, and problems such as the lack of the land edge are likely to occur.

According to the pneumatic tire configured as described above, the arrangement pitch of both the slow and steep inclined grooves 1, 2, 3, and 4 is smaller than that of the tire shown in FIG. As the number of grooves existing in the ground plane increases, the edge effect due to the groove edges of each groove increases. Since the operability is improved, the steering stability on a wet road surface can be greatly improved, especially in a low temperature range, and the difference in the rigidity of each block is reduced to stabilize the ground contact state. In addition, the contact pressure can be made uniform, the cornering power can be increased, and the change in stability during turning can be more effectively suppressed.

While the illustrated embodiment has been described above, the pattern center can be biased toward one of the tread ends with respect to the tread center.

[0027]

【Example】

Embodiment 1 An embodiment of the present invention will be described below. Table 1 shows an example of steering stability on a wet road surface, together with a conventional tire and a comparative tire. Here, the example tire has the tread pattern shown in FIG. 1 as a basic pattern, and the comparative example tire has the tread pattern shown in FIG. 3 as a basic pattern. Changed as shown.

Evaluation of the steering stability performance was as follows.
55R15 tire with standard rim (JATMA YEAR
BOOK) and set the filling internal pressure to 2.0
Attach it to a modified race model of a commercial vehicle as kgf / cm ² , measure the lap time on a wet circuit course with a depth of 3 mm by a test driver under the condition that the load applied to the vehicle is one person riding load. At the same time, the comparative example tire 1 was used as a control to perform index evaluation.

Here, the lap time when the road surface temperature is 15 ° C. or more is an average value of the lap times at the temperatures of 15 ° C. and 19 ° C. When the road surface temperature is less than 15 ° C., the lap time is 3 ° C. Similar average values were obtained at each temperature of 9 ° C.

[0030]

[Table 1]

As shown in Table 1, all of the tires of the present invention can be operated on a wet road surface by selecting the arrangement pitch of each of the gentle and steep slope grooves within an appropriate range with respect to the tire circumference. It is clear that the performance can be significantly improved, especially at low and normal temperatures, respectively.
Further, when the arrangement pitch of each groove is out of the range of the embodiment, the wet steering performance is sharply reduced to the same level as that of the comparative example tire 1, and the expected effect of the present invention is achieved. Obviously, you can't.

Example 2 Table 2 shows the steering stability performance on a wet road surface when the negative rate is used as a parameter. The tires of the examples in this example are the same as those in Table 1 except for the negative rate. The tire had the same dimensional specifications as the tire 2 of the example. Further, both the performance evaluation condition and the temperature condition were the same as in the case of Example 1.

[0033]

[Table 2] According to Table 2, the steering stability on a wet road surface is such that the negative rate is 30 to irrespective of whether the temperature is low or normal.
It is particularly excellent in the range of 40%, and it can be seen that it is particularly remarkable on a low-temperature road surface.

[0034]

As is apparent from the above description, according to the present invention, the arrangement pitch of the gentle inclined grooves in the tire circumferential direction is 1.8 to 2.2% of the tire circumferential length. By setting the pitch of the steeply inclined grooves in the tire circumferential direction to be 3.6 to 4.4% of the tire circumferential length, compared to the tire previously proposed by the applicant, in both the low temperature range and the normal temperature range. Also, the steering stability on a wet road surface can be remarkably improved, and a change in stability during turning can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a development view of a tread pattern showing one embodiment of the present invention.

FIG. 2 is a tread pattern developed view of a conventional tire.

FIG. 3 is a developed view of a tread pattern of a tire according to the above proposal.

[Explanation of symbols]

 1,2 Slightly inclined groove 3,4 Steeply inclined groove 5,6 Secondary inclined groove

Claims (4)

[Claims] The present invention provides two types of gently and sloping grooves on a tread tread portion extending in a direction in which the tires are expanded upward from below in a front view of a mounting posture of the tire on a vehicle. It is formed at an angle of 45 to 80 ° with respect to the tire circumferential direction, and the steeply inclined groove is formed at an angle of 5 to 30 ° with respect to the tire circumferential direction. The gentle slope groove extends from the pattern center portion so as to intersect the steep slope groove, and the steep slope groove extends from the pattern center portion to the tread end side over a width of 80% or more of the tread contact width. The pitch of the gently inclined grooves in the tire circumferential direction is set to 1.8% to 2.2% of the tire circumferential length, and the pitch of the steeply inclined grooves in the tire circumferential direction is set to 3.6% of the tire circumferential length. Air with excellent handling stability of 4.4% Containing tires. 2. The method according to claim 1, wherein a ratio of a groove width of the gentle slope groove to a groove width of the steep slope groove is 50 to 100%.
A pneumatic tire having excellent steering stability according to item 1. 3. Assemble the rim with a standard rim and set the internal pressure to 2.0kg
The pneumatic tire excellent in steering stability according to claim 1 or 2, wherein a negative rate on a ground contact surface under application of f / cm ² and a load of 350 kgf is 25 to 45%. 4. The groove width of the steeply inclined groove measured in the tread width direction is assembled to a standard rim, and the internal pressure is set to 2.0 kgf / cm.
^{2. The} pneumatic tire having excellent steering stability according to any one of claims 1 to 3, wherein the pneumatic tire has a width of 3 to 8% of a contact width under a load of 350 kgf.