JPH04208608A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To heighten pattern rigidity and a water discharge quality together and improve traveling performance on both wet and dry roads, by providing main lateral grooves which extend continuously from one side of a tread edge to the other side and are inclined at angles that are different at a tread crown sphere and tread shoulder spheres. CONSTITUTION:At a pneumatic tire 1A, a compression which is the ratio of a tire section height H to a tire width H, H/W, is set at less than 70%. At this time, main lateral grooves 10 provided at equal pitch intervals in a tire circumferential direction are provided in recess at a tread surface, and the improvement of a water discharge quality and pattern rigidity is realized. At the center groove portion 10A of a main lateral groove 10, a linear main portion whose groove center line l is inclined at the inclination angle alpha of 10 deg.-20 deg. in regard to the tire circumferential direction, is provided, and its both end portions are bent toward a tread edge (e) with the inclination angle alpha being gradually increased. Meanwhile, side groove portions 10B whose inclination angle beta in regard to the tire circumferential direction is being gradually increased, have their outer ends opened at the tread edge (e). Also, the inclination angle betais set at the range of 60 deg.-90 deg..

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can improve drainage performance while increasing the pattern rigidity of the tread portion, and can simultaneously improve running performance on both wet and dry roads. Regarding pneumatic tires.

[Conventional technology]

As road networks become more developed and vehicles become more sophisticated, tires are required to have excellent high-speed running performance. Radial tires are increasingly being used.

On the other hand, with such a flat tire, when driving at high speed on a wet road surface, due to expansion during contact with the ground and decrease in ground pressure, there is a gap between the tire and the road surface as shown in Figure 6 (a). To,
The water film a tends to enter in a wedge shape from the direction of travel. Therefore, in order to drain this water film a out of the tire contact area, conventionally, the tread part is provided with a number of circumferential lines according to the tread width, as shown in FIGS. 7(a) and 7(b). A block-shaped tread pattern is formed by subdividing the tread surface by vertical grooves and horizontal grooves C in a direction that intersects with the vertical grooves. Drainage performance is the area ratio between the sea area made up of the grooves and c and the ridged area made up of the remainder of the groove in the contact area. Well, there is a difference between drainage and greenpability.
There is a conflicting relationship. Therefore, improvements in road running performance in conventional pattern designs are achieved by balancing the contradictory properties of water drainage and grip. The pitch, groove, etc. are set.

[Problem to be solved by the invention]

However, in conventional tread patterns, the tread surface is subdivided into blocks, so when obtaining an appropriate sea/land ratio, the stiffness of each block is reduced, resulting in a significant reduction in pattern rigidity. The resulting pattern collapse reduces the effective groove volume and impairs drainage performance, while also accelerating uneven wear and deteriorating steering stability.

In particular, race tires use a softer rubber material in the tread compared to general tires in order to increase the coefficient of friction with the road surface and further improve grip, so the above problem is even more pronounced. becomes. The present invention is based on providing a main lateral groove that extends smoothly and continuously from one tread edge to the other, thereby increasing pattern rigidity and improving drainage performance, improving running performance on both wet and dry roads. The aim is to provide pneumatic tires that can be used.

[Means to solve the problem]

In order to achieve the above object, the pneumatic tire of the first invention is a flat radial tire having an aspect ratio of 70% or less, which is the ratio H/W of the tire cross-sectional height H and the tire width W,
The tread part has an inclination angle α of 10 to 20 degrees with respect to the tire circumferential direction in the tread crown area, an inclination angle β1, β2 of 60 to 90' in the tread shoulder area, and from one tread edge to the other tread edge beyond the tire equator. Main lateral grooves are provided that extend continuously and smoothly and are spaced apart in the circumferential direction of the tire. In addition, in the tread shoulder area,
It is preferable to provide a sub-trough groove between the main lateral grooves that opens at the tread edge and is inclined at the same angle as the trend shoulder area of the main lateral groove.

Further, the pneumatic tire of the second invention is provided with a vertical groove extending in the circumferential direction of the tire on the inner tire facing toward the vehicle when mounted on the vehicle.

[For production]

Since the main lateral grooves of the pneumatic tire of the present invention configured as described above are formed continuously from one tread edge to the other tread edge, the ridges sandwiched between the main lateral grooves extend long in the shape of ribs. However, a decrease in pattern rigidity can be effectively suppressed.

Furthermore, according to the analysis of the present inventors, the water film a shown in FIG. 6(a) that infiltrates in a wedge shape during high-speed running is cut even by the tread surface and the road surface at the edge side, so that the streamline f is 6 towards the side of the tire as shown in Figure 6(b).
It has been found that water flows at an angle of 0 to 90', and that a water accumulation point g occurs near the tire equator.

Therefore, in the present invention, in the crown region at the center of the tread, where the ground contact length is long and the influence of water film becomes severe, and where water is present, the main lateral groove is made into a shallow groove of 10 to 20', which approximates a vertical groove with a high drainage effect. It is inclined at an angle α. In addition, in the tread shoulder region along the tread edge, the streamline f
The water film is smoothly continuous with deep inclination angles β1 and β2 close to , and therefore the water film can be efficiently discharged along the streamline.
Drainage performance can be greatly improved without dividing the tread surface into blocks.

Moreover, since the main transverse groove in the crown region is inclined at an angle α,
While it has the effect of breaking a water film, it has Seeα times the length of the vertical grooves extending in the circumferential direction, and can increase the sea/land ratio without encountering conventional horizontal grooves.

Furthermore, the rib portion, which has increased rigidity by being continuously interposed between the main lateral grooves, extends in the crown region where the ground pressure is high when traveling straight, in a manner similar to the circumferential acting force from the ground plane, and when turning. In the shoulder region where the ground contact pressure is large, the force extends in a manner similar to the lateral acting force. That is, since the rib portion has increased strength and rigidity depending on the direction of the applied force during running, the handling stability and durability can be further improved.

In addition, especially for racing tires, in order to improve turning performance, a negative camber angle is given when installed on the vehicle, and when driving straight, the contact length of the inner measurement facing the vehicle side or the outer contact length is Compared to measurement, it becomes a dog.

Therefore, in the second invention, circumferential longitudinal grooves are formed in the core within the core to improve drainage performance.

C Example] An embodiment of the present invention will be described below with reference to the drawings.

In the figure, the pneumatic tire IA of the first invention has a radial arrangement in which both ends from the tread part 2 to the sidewall part 3 to the bead part 4 are folded back and locked around the beat core 5 of the bead part 4. Equipped with carcass 6. A strong belt layer 7 is wrapped around the tire circumferentially outside the carcass 6 in the radial direction and inside the tread portion 2, and its hoop effect reduces the ratio between the tire cross-sectional height H and the tire width W. H/
The flatness ratio, which is W, is restricted to 70% or less. This improves the tire's lateral rigidity and tread rigidity, while increasing the ground contact width and improving high-speed running performance.

Further, the tread surface, which is the outer surface of the tread portion 2, is provided with main lateral grooves 10 spaced apart at equal pitches in the circumferential direction of the tire, thereby improving drainage performance and baton rigidity. is measured.

The tread surface has a tread crown area P at the center of the tread that passes over the tire equator CO, a measurement area Q on both sides of the tread crown area P, and
The measurement Q includes a tread shoulder region Q1 at both ends of the tread extending along the tread edge e, and a tread intermediate region Q2 between the tread shoulder region Q1 and the tread crown region P.

Further, the tread crown area P is located at the tread edges e, e.
The width of the tread shoulder area Q1 is at least 115 times, more preferably 1/4 times or more, the width of the tread WT, which is the axial distance between the treads.
It has a width L1 that is 1/6 times or more of T. Note that such Meijo P, Ql, and Q2 are areas set for the WT in the tread, and are not determined by other factors such as the radius of curvature of the tread surface and the position of the eccentric point of the curvature. .

The main lateral groove 10 extends continuously and smoothly from one tread edge e over the tire equator CO to the other tread edge e, as shown in FIG. 2 when the tread pattern is developed. In the example, it has a substantially S-shape, and includes a central groove portion 10A passing through the tread crown region P, a side groove portion 10B passing through the tread shoulder region Q1, and a central groove portion 10A and side groove portion 10B passing through the tread intermediate region Q2. and an intermediate groove portion 10C that smoothly joins.

Further, the central groove portion 10A has a linear main portion whose groove center line l is inclined at an inclination angle α of 10° or more and 20° or less with respect to the tire circumferential direction, and in this example, both end portions thereof are tread-shaped. It is curved with the inclination angle α gradually increasing toward the edge e. In addition, also in the above-mentioned both end portions, the groove center line l
The slope of the tangent line is 10° to the tire circumferential direction.
It is 20°. That is, the central groove portion 10A is inclined at a shallow angle of inclination α in the range over its surface length, which allows it to penetrate between the road surface and the tire equatorial CO.
It can effectively drain away the water film that accumulates in the vicinity. Moreover, since the central groove portion 10A is inclined, the groove length in the ground contact area can be expanded by Seeα compared to the vertical groove, and the necessary sea/land ratio can be secured in a well-balanced manner without providing the conventional horizontal groove.

Note that when the inclination angle α is more than 20°, the main lateral groove 10.
The rigidity in the circumferential direction of the tread crown region P of the rib portion 11 interposed between the rib portions 10 becomes insufficient, which impairs the resistance to stress applied from the road surface when traveling straight, and reduces straight traveling performance. Furthermore, when the inclination angle α is smaller than 10, the effect of breaking the water film is poor, impairing the ground contact, and at the same time, the rib rigidity decreases, as a new horizontal groove is required to be formed to obtain the necessary sea/land ratio. This will lead to a decrease in steering stability.

Further, the side groove portion 10B has a streamline f shown in FIG. 6(b).
In this example, the groove is approximately arc-shaped, and its inner end is connected to the central groove part 10A via the intermediate groove part 10C, and the outer end thereof extends by gradually increasing the inclination angle β with respect to the tire circumferential direction. , opens at the tread edge e. In this example, the inclination angle β is the angle at which the tangent to the groove center line l intersects with the tire circumferential direction, and the inclination angle β is 60′ or more and 900′ over the entire length of the side groove portion 10B.
It is set in the following range. In this example, the inclination angle β at the inner end is approximately 60°, and the inclination angle β at the outer end is approximately 90°.
It is approximately 0°.

Since the side groove portion 10B is formed in this way, the central groove portion 1
The water passing through 0A and the intermediate groove portion 10C can be effectively drained along the streamline f, and the wet running performance can be greatly improved. Moreover, since the rib portion 11 extends along the side groove portion 10B in the tread shoulder region Q1, the resistance against lateral force acting during turning is increased, and it is possible to improve turning characteristics and steering stability.

Further, in this example, in order to further improve the drainage performance, at least the groove width of the side groove portion 10B is gradually increased toward the tread edge e, while the groove width between the main lateral grooves 10 and the tread shoulder region Q1 is the same as that of the side groove portion 10B. One or two independent auxiliary grooves 12 that are inclined at an angle and open at the outer end or tread edge e.
The book is forming. In this example, the inner end of the sub-trough groove 12 passes through the tread shoulder region Q1 and terminates within the tread intermediate region Q2.

Note that the main lateral groove 10 can be made asymmetrical so that the inclination angle β1 in the inner tread shoulder area QIA facing the vehicle side is different from the inclination angle β2 in the outer tread shoulder area QIB when the main lateral groove 10 is mounted on the vehicle. The number of grooves 12 formed may be different between the inner and outer tread shoulder areas QIASQ2B.

Further, a developed view of the tread pattern of the pneumatic tire IB of the second invention is shown in FIG.

The pneumatic tire IB is a high-speed tire for racing, for example, and is mounted on a vehicle with a negative camber angle in order to improve turning stability. Therefore, when the pneumatic tire IB runs straight, it exhibits a substantially triangular contact surface shape S1 in which the contact length of the inner tread shoulder area QIA facing the vehicle side is large, as shown in FIG. 4(a), and When turning, the contact surface shape S2 in the transient state of the horizontally long road rectangle shown in FIG.
The contact surface shape S3 shown in FIG. 4 (C) has a dog contact length.
to move to.

Therefore, in order to improve the wet running performance of a tire with such a contact surface shape, the contact length during straight running is a dog, and the inner measurement QA, which is susceptible to the influence of water films, in this example, the inner tread shoulder area QIA, At least one, in this example one, vertical groove 13 is provided that extends in the circumferential direction of the tire and has a high drainage effect. Furthermore, even when such a longitudinal groove 13 is formed, the rib portion 1 in the tread crown region P and the outer measurement QB
Since it extends continuously without being subdivided into blocks, the required pattern rigidity is maintained when traveling straight and when turning. In addition, in this example, in order to suppress uneven sea/land ratio within the ground contact area due to the formation of the vertical grooves 13, one sub-tank groove 12 is provided in the inner tread shoulder area QIA, and one sub-tank groove 12 is provided in the inner tread shoulder area QIA. Two sub-tank grooves 12 are formed in the shoulder area QIB to maintain a balance in ground contact.

Note that FIG. 5 shows a tread pattern in which one vertical groove 13 is further formed in the inner measurement QA.

〔Concrete example〕

Tire size 225150ZR16 with the tread pattern shown in Figure 7(a) having the sea/land ratio shown in Table 1
A prototype tire was manufactured, and the hydroplaning speed and lateral acceleration were measured using a lateral hydroplaning test, and the turning time and lateral acceleration were measured using a wet turning test. The measurement results at that time are listed in Table 1 together with the conventional tire shown in FIG. 7(a).

〔Effect of the invention〕

The pneumatic tire of the present invention has an inclination angle of 10 to 20 degrees in the tread crown region and 60 to 90 degrees in the tread shoulder region, which extends smoothly from one tread edge to the other. Since the main lateral groove is provided with an inclination angle of , it is possible to increase both pattern rigidity and drainage performance, thereby improving running performance in both wet and dry conditions.

Table 1

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the pneumatic tire of the present invention, FIG. 2 is a developed view showing the tread pattern of the first invention, and FIG. 3 is a developed view of the tread pattern of the second invention. 4(a) to (C) are route maps showing the shape of the ground contact surface; FIG. 5 is a developed view showing another embodiment of the tread pattern of the second invention; FIG. Figures (a) to (b)
) is a route map explaining drainage performance, and FIGS. 7(a) to 7(b) are developed views showing the tread pattern of a conventional tire. 10... Main lateral groove, 12... Sub-tank groove, 13...
Vertical groove P...Tread crown area, Q/(llI area,
QA... Measurement within Ql... Tread shoulder area. Patent Applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent Attorney Tadashi Naemura Figure 2 Figure 31g Figure 4 (a) QIA 115! ! F Figure 6 (a) a ＼ Figure 6 (b)

Claims (1)

[Scope of Claims] 1. A flat radial tire having an aspect ratio of 70% or less, which is the ratio H/W of the tire cross-sectional height H and the tire width W, wherein the tread part has an inclination in the tread crown area with respect to the tire circumferential direction. The angle α is 10 to 20 degrees, the inclination angles β1 and β2 in the tread shoulder region are 60 to 90 degrees, and the tread extends continuously and smoothly from one tread edge beyond the tire equator to the other tread edge, and is spaced apart in the tire circumferential direction. A pneumatic tire with a main horizontal groove. 2. The tread according to claim 1, wherein the tread portion is provided with a sub-lateral groove that is provided between the main lateral grooves in a tread shoulder region, opens at a tread edge, and is inclined at the same angle as the tread shoulder region of the main lateral groove. pneumatic tires. 3 A flat radial tire with an aspect ratio of 70% or less, which is the ratio H/W of the tire cross-sectional height H and the tire width W, and the tread part has an inclination angle α of 10 to 20 with respect to the tire circumferential direction in the tread crown area. °, the inclination angles β1 and β2 in the tread shoulder region are 60 to 90°, and the main lateral grooves extend continuously and smoothly from one tread edge beyond the tire equator to the other tread edge, and are spaced apart in the tire circumferential direction. A pneumatic tire is provided with vertical grooves extending in the tire circumferential direction on both sides of the tread crown area and on the inner side area facing toward the vehicle when mounted on the vehicle, of both sides including the tread shoulder area. 4. The tread according to claim 3, wherein the tread portion is provided with a sub-lateral groove that is provided between the main lateral grooves in the tread shoulder region, opens at the tread edge, and is inclined at the same angle as the tread shoulder region of the main lateral groove. pneumatic tires.