JPH0825916A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To secure excellent traction performance and improve wet drain performance at the time of high speed travel. CONSTITUTION:A tread part is provided with two kinds of easy and steep inclined grooves 1, 2 and 3, 4 opened upward from the lower parts from the front view in the mounted attitude to a vehicle. The easy inclined grooves are formed linearly at an angle of 45-80 deg. to the tire circumferential direction, and the steep inclined grooves 3, 4 are formed linearly at an angle of 5-30 deg. to the tire circumferential direction. The intersection angles of both easy and steep inclined grooves are to be 30 deg. or more. The easy inclined grooves 1, 2 are extended from a pattern center part and opened to the steep inclined grooves at the tread end part, and the steep inclined grooves 3, 4 are extended to the tread end side, over the width WH of 80% or more of the tread ground width TW. The disposition pitch Pa in the tire circumferential direction of the steep inclined grooves 3, 4 is to be almost double of that of the easy inclined grooves 1, 2, and the groove width of the steep inclined grooves 3, 4 is to be equal to or more than that of the easy inclined grooves 1, 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which is applied to high-power vehicles such as sports cars and racing cars and exhibits excellent wet drainage performance.

[0002]

2. Description of the Related Art Conventional tires applied to high-power vehicles such as sports cars and racing cars are illustrated in FIG. 5, and FIG. 5 (a) shows front tires and FIG.
(B) shows the rear tires, respectively.

Here, a plurality of circumferential main grooves 21 which linearly extend in the tire circumferential direction and contribute to the improvement of wet drainage performance are provided in the tread tread portion, and the circumferential main grooves 21 are provided. Inclined main groove 2 that intersects the groove 21 at an angle and contributes to the lateral drainage function and the edge effect.
2 in a zigzag pattern over the width of the tread, and
Between the two inclined main grooves, extending substantially parallel to them,
An inclined auxiliary groove 23 is provided for controlling the ground contact property and the block rigidity that affects the road 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 traveling at high speed.
In recent years, for the purpose of further improving wet drainage performance,
Various so-called directional patterns have been proposed in which directional inclined grooves are combined with circumferential linear grooves.

[0005]

In such a proposed technique, when the angle of the directional inclined groove with respect to the tire circumferential direction is 45 ° or less in order to improve wet drainage performance, a large horsepower is required. For sports cars, racing cars, etc. that have it, the edge effect in the tire rotation direction becomes small and the required traction performance cannot be obtained, while the angle with respect to the tire circumferential direction exceeds 45 °. When the size is set, there is an inconvenience that sufficient drainage performance cannot be obtained although traction performance can be obtained.

The present invention has been made to solve the above problems, and a pneumatic tire capable of effectively improving wet drainage performance during high speed running while ensuring excellent traction performance. Among them, it provides radial tires.

[0007]

A pneumatic tire according to the present invention has a tread tread portion continuously extending in a direction in which the tire spreads from the lower side to the upper side in a front view of the mounting posture of the tire on a vehicle. Two types of slanting grooves that extend slowly are provided, and the slanting groove is 45 to 80 in the tire circumferential direction.
°, preferably in the range of 55 to 70 °, and the steep groove in the tire circumferential direction in the range of 5 to 30 °, preferably 10 to 25 °, both of which are substantially straight lines. Formed in a rectangular shape, and the angle of intersection of the two inclined grooves on the acute angle side is 30
The angle is not less than 30 °, preferably 30 to 60 °, and the gently-sloping groove is extended from the pattern center portion, in other words, the pattern center position or a position in the vicinity thereof, and the tread end portion is opened to the steeply inclined groove. Further, the steep groove is extended from the pattern center portion to the tread end side over a width of 80% or more of the tread contact width, and the pitch of the steep groove in the tire circumferential direction is gently inclined. The groove width is approximately twice that of the groove, and the groove width of the steeply inclined groove is equal to or larger than that of the gently inclined groove.

Here, the extending width of the steeply inclined groove is
If it opens to the pattern center, it means the actual extension width of the steep groove, and if it does not open to the pattern center, the width of the pattern center area where the steep groove is not formed. It means the apparent extension width including.

Preferably, the flatness of the tire is 30.
The range is up to 65%, and the steep grooves located on each side of the pattern center are arranged so as to be offset from each other in the tire circumferential direction, and the negative ratio in the ground contact surface is 35 to 45%. The range is.

Further, preferably, the pattern center is located at a position closer to the outside of the vehicle than the tread center of the tire mounted on the vehicle, or aligned with the tread center.

More preferably, the groove arrangement is asymmetric with respect to the tread center, and the groove width of the steeply inclined groove is
Wider than that of the gently sloping groove and also extending continuously on each side of the pattern center on the pattern center.

[0012]

In this pneumatic tire, by eliminating the circumferential groove from the tread surface, it is possible to suppress buckling along the circumferential direction of the tread.
By setting the angle of the steeply inclined groove with respect to the tire circumferential direction at 5 to 30 °, it is possible to secure the required block rigidity and provide excellent wet drainage performance. That is, when observing the flow of water in the tire ground contact surface, water is discharged to the front and side surfaces of the ground contact surface within an angle range of up to 30 ° with respect to the tire circumferential direction. By forming the groove as a steeply inclined groove extending at an angle of 30 ° or less with respect to the tire circumferential direction, excellent wet drainage performance can be provided rather than the straight circumferential groove. On the other hand, when the angle of the steeply inclined groove is less than 5 °, the required block width cannot be secured, especially at the pattern center portion, and in some cases, the steeply inclined groove is used. The corners of the blocks to be sandwiched become too acute, and sufficient block rigidity cannot be ensured.

Further, here, the angle of the gently inclined groove with respect to the tire circumferential direction is set in the range of 45 to 80 °, whereby smooth and effective transmission of a large engine torque to the road surface is ensured. In other words, if it is less than 45 °,
The block edge does not bring excellent edge effect, and thus high traction performance.
If the angle exceeds 0 °, the edges of the blocks come into contact with the road surface almost at the same time, which causes a problem that vibration and noise increase.

Further, in this tire, a high block rigidity is ensured by setting the angle of intersection of the steep sloped grooves on the acute angle side to be 30 ° or more. Here, the angle is preferably 60 °
By the following, the branching of the flow in the groove is smoothed, the energy loss of running water is reduced, and the reduction of drainage efficiency is prevented.

Further, by opening the gently sloping groove to the steeply sloping groove at the end portion of the tread, the gently sloping groove can effectively exhibit the drainage function to the side of the tire. It is particularly effective when the gently sloping groove is opened at the tread end directly or indirectly in addition to the above.

Furthermore, by setting the extension width of the steeply inclined groove to be 80% or more of the tread ground contact width, wet drainage performance can be improved without lowering steering stability performance. That is, the suspension of a racing car or the like is set so that the tread surface of the tire contacts the ground almost uniformly over its entire width, and it is not necessary to particularly increase the block rigidity in the shoulder region. Rigidity, etc. can be made almost uniform over a width of 80% or more of the tread contact width, yet sufficient steering stability performance can be brought, and wet drainage performance is improved as the area where the steep groove is formed becomes wider. Become.

By the way, the arrangement pitch in the tire circumferential direction of such a steeply inclined groove formed over most of the tread ground contact width is approximately twice that of the gently inclined groove so that a high block rigidity is obtained. Can be secured. Here, the steeply inclined groove preferably has a wide groove width from the viewpoint of drainage, but the gently inclined groove mainly contributes to securing an edge component and improving traction performance. Therefore, the groove width of the gently sloping groove does not need to be so large, and therefore, the gently sloping groove width may be equal to or less than the steeply sloping groove width.

In this tire, the flatness ratio is 30.
When it is set to ˜65%, the drainage property, which is generally disadvantageous, can be remarkably improved.

When the steeply sloping grooves located on the respective side portions of the pattern center are arranged so as to be displaced from each other in the tire circumferential direction, the steeply sloping grooves do not bring about a decrease in block rigidity. It can be sufficiently close to the pattern center, which can further improve wet drainage performance.

It is to be noted that, by arranging the steeply inclined grooves on the respective sides without shifting in the circumferential direction, the steeply inclined grooves are extended in a substantially V shape at the pattern center portion. However, by providing the pattern center with a short circumferential straight groove that continuously extends to the V-shaped portion of the steep groove, it is possible to achieve both high block rigidity and excellent wet drainage performance.

Here, the negative ratio in the ground plane is set to 35.
When it is set to ~ 45%, excellent wet drainage performance can be ensured, and yet deterioration of block rigidity and eventually steering stability performance can be sufficiently prevented. When the tires are located closer to the outer side of the vehicle than the tread center, it is effective to increase the proportion of the steeply sloping grooves in the inner side of the vehicle, which greatly contributes to the wet drainage performance during turning of the vehicle. Can be increased. On the other hand, when the pattern center is aligned with the tread center, the drainage performance when traveling straight ahead can be improved due to the drainage property even on the left and right.

Further, when the groove arrangement is asymmetric with respect to the tread center, it becomes possible to set the block rigidity according to the difference in the ground contact property due to the setting of the suspension, and the groove width of the steep groove is If the groove is made wider than that of the gently sloping groove, effective drainage becomes possible in a wet road condition with a deep water depth.

In addition, when gently sloping grooves extending on the respective sides of the pattern center are continuous on the pattern center and both of the gently sloping grooves extend in a substantially V shape, The strong edge catching effect can improve the traction performance.

[0024] Thus, according to the present invention, excellent steering stability can be achieved and the traction performance and the wet drainage performance can both be achieved at a high level.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a tread pattern of a front wheel tire showing an embodiment of the present invention, and FIG. 2 is an example of a tread pattern of a rear wheel tire used together with the tire shown in FIG. Since the internal reinforcing structure of the tire is similar to that of a general radial tire, the illustration is omitted here.

[0026] In this example, in a front view of a tire mounting posture of the vehicle, the pattern center X ₀ -X _0, is positioned in polarization brought outside of the vehicle from the tread center, the pattern center X ₀ -X ₀ As the center, two types of inclined grooves 1, 2, 3 and 4 are provided, which extend continuously from the lower side to the upper side in a direction in which they both expand.

Here, the gently-sloped grooves 1 and 2 extending substantially linearly on each side of the pattern center X ₀ -X _0.
On the pattern center to form the gently-sloped grooves 1 and 2 in a substantially V shape,
The pattern center X among those gently sloping grooves
All that extend outside the vehicle from _0- X ₀ are opened at the tread end, and the gently-sloping groove 2 extending inside the vehicle is opened at the tread end portion at a steep groove described later. , Every other one is opened at the tread end, and the remaining gently sloping grooves 2 are finished at the opening positions to the steeply sloping grooves. Here, in the figure, the gently sloping groove 2 that opens to the tread end can also be terminated at the position that opens to the steeply sloping groove.

Further, here, the angles φ ₀ and φ ₁ of the respective gently inclined grooves 1 and 2 with respect to the tire circumferential direction are both 45 to 80 °, preferably 55 to 70.
The range is °.

Further, in this example, the steep grooves 3 and 4 which are located apart from the pattern center X ₀ -X ₀ and extend in a substantially straight line are arranged so as to be offset from each other in the tire circumferential direction. At the same time, on the pattern center side, each of them reaches the pattern center X ₀ -X ₀ and is terminated. On the other hand, the tread end side portion of the steeply inclined groove 3 extending to the outside of the vehicle from the pattern center X ₀ -X ₀ is terminated at the position where it opens to the gently inclined groove 1,
Further, the tread end side portion of the steeply inclined groove 4 extending inward of the vehicle is opened in the bending inclined groove 5 which is inclined in the same direction as the steeply inclined groove 4 and is opened at the tread end, and is ended.

In addition, the angles θ ₀ and θ ₁ of the steeply inclined grooves 3 and 4 with respect to the tire circumferential direction are in the range of 5 to 30 °, preferably 10 to 25 °,
At the same time, the angle of intersection of the gently 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 °.

In this tire, the steep groove 3,
4 has an extension width WH in the tread width direction of 80% or more of the tread ground contact width TW, and the pitch Pa of the steeply inclined grooves 3 and 4 in the tire circumferential direction is set to the gently inclined grooves 1 and 2. Of the same pitch Pb of
The groove widths of the steeply inclined grooves 3 and 4 are equal to or larger than the groove widths of the gently inclined grooves 1 and 2, and preferably larger than that.

Since the pattern center X ₀ -X ₀ is offset from the tread center in the tire constructed as described above, the groove arrangement there is
Asymmetric with respect to the tread center. By the way, more preferably, the flatness of the tire is 30 to 65.
% Range, and the negative ratio in the ground plane is 35
˜45% range.

The above description is the same for both the front wheel tire shown in FIG. 1 and the rear wheel tire shown in FIG. By arranging 3 and 4 under specific conditions, it is possible to bring about the operational effects as described above with respect to steering stability performance, traction performance and wet drainage performance.

FIG. 3 is a tread pattern of a front tire and a rear tire showing another embodiment of the present invention. In this example, in particular, the amount of relative deviation of the steeply inclined grooves 3 and 4 in the tire circumferential direction is reduced, and the edge of each of the steeply inclined grooves 3 and 4 on the pattern center side is changed to the pattern center X ₀ −. X ₀ is not opened, but the gently inclined grooves 1 and 2 are opened in the vicinity thereof, and the steep inclined grooves 3 and 4 are further opened.
The gently sloping grooves 1 and 2 having open edges are made to communicate with the other gently sloping grooves 1 and 2 that are adjacent to each other in the circumferential direction by the short circumferential linear groove 6 located on the pattern center. The other configurations are almost the same as those described above.

Here, since the steeply inclined grooves 3 and 4 do not open to the pattern centers X _{0 to} X ₀ , a steeply inclined groove is formed between the edges of the steeply inclined grooves 3 and 4 on the pattern center side. Although there is a region having a width w which is not formed, the steeply inclined groove extending width WH here includes the width w.

Further, in the example shown here, the relative deviation amount of the steeply inclined grooves 3 and 4 in the tire circumferential direction can be set to zero, and also by this, under the action of the circumferential linear groove 6,
The rigidity of each block existing in the pattern center portion can be made sufficiently uniform in the tire circumferential direction, and a sufficiently high rigidity can be imparted to each of these blocks.

A tire constructed as described above also has
Since the various conditions for the respective inclined grooves 1, 2, 3, 4 are satisfied, it is possible to bring about the same operational effect as the above-mentioned embodiment.

FIG. 4 shows a tread pattern showing still another embodiment of the present invention. This example is substantially equivalent to the tread pattern in which the pattern center coincides with the tread center in the embodiment shown in FIGS. . Therefore, also with this tire, it is possible to bring about the same operational effects as the above-mentioned embodiment in terms of steering stability performance, traction performance and wet drainage performance.

[Comparative Example] A comparative test regarding steering stability performance, traction performance and wet drainage performance between the inventive tire and the conventional tire will be described below.

◎ Test tire The size of the front tire is 215 / 55R13 and the tread contact width (TW) is 216 mm, and the size of the rear tire is 310 / 40R13 and the tread contact width (TW) is 31.
It was set to 0 mm.

Invention Tire 1 A front tire and a rear tire having the respective tread patterns shown in FIGS. 1 and 2 were used. Tables 1 and 2 show the dimensions of each tire.

[0042]

[Table 1]

[0043]

[Table 2]

Invention Tire 2 A front tire and a rear tire having the respective tread patterns shown in FIGS. 3 (a) and 3 (b) were used. The dimensions of each tire are shown in Tables 3 and 4.

[0045]

[Table 3]

[0046]

[Table 4]

Invention Tire 3 A front tire and a rear tire having the respective tread patterns shown in FIGS. 4 (a) and 4 (b) were used. The dimensions of each tire are shown in Tables 5 and 6.

[0048]

[Table 5]

[0049]

[Table 6]

Conventional tire A front tire and a rear tire having the respective tread patterns shown in FIGS. 5 (a) and 5 (b) were used. The dimensions of each tire are shown in Tables 7 and 8.

[0051]

[Table 7]

[0052]

[Table 8]

◎ Test method Tires with a filling internal pressure of 4.0 kgf / cm ² were mounted on an actual vehicle, and the vehicle was run under load conditions equivalent to one passenger.
The steering stability performance was evaluated by the driver's feeling in circuit driving, and the traction performance was evaluated by measuring the acceleration running time in a straight section of 500 m.

Regarding the wet drainage performance, in addition to performing a feeling evaluation of the rate of occurrence of the hydroplaning phenomenon when running straight on a wet road surface with a water depth of 5 mm, the limit when running on a wet road surface with a water depth of 5 mm and a radius of 80 m The lateral G was measured and the feeling of the rate of occurrence of the hydroplaning phenomenon was evaluated.

◎ Test Results The results of each of the above tests are shown in Table 9 as an index with the conventional tire as a control. The larger the index value, the better the result.

[0056]

[Table 9]

[0057]

As is apparent from the above comparative example, according to the present invention, two kinds of sloped grooves are provided on the tread surface under a certain condition, so that a sports car,
When applied to a high-power vehicle such as a racing car, excellent steering stability performance and traction performance can be provided, and wet discharge performance can be greatly improved in both straight traveling and turning traveling.

[Brief description of drawings]

FIG. 1 is a tread pattern for a front tire according to an embodiment of the present invention.

2 is a view illustrating a tread pattern for a rear wheel tire used with the tire shown in FIG. 1. FIG.

FIG. 3 is a tread pattern showing another embodiment of the present invention.

FIG. 4 is a tread pattern showing still another embodiment of the present invention.

FIG. 5 is a tread pattern showing a conventional example.

[Explanation of symbols]

1, 2 gently inclined groove 3, 4 steeply inclined groove 6 circumferential straight groove φ ₀ , φ ₁ , φ angle θ ₀ , θ ₁ , θ angle Pa, Pb groove arrangement pitch WH steeply inclined groove extended width TW tread ground width

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B60C 11/113 7504-3B B60C 11/08 D

Claims (9)

[Claims] 1. A tread tread portion is provided with two types of sloped grooves that extend in a direction in which the tires spread out from the lower side to the upper side in a front view of the tire mounting posture on the vehicle. The groove is formed substantially linearly in the range of 45 to 80 ° with respect to the tire circumferential direction, and the steep groove is formed substantially linearly in the range of 5 to 30 ° with respect to the tire circumferential direction. And the intersecting angle of the two steep sloped grooves is 30 ° or more, the gentle sloped groove is extended from the pattern center portion, and the steeply sloped groove is opened at the tread end portion. From the pattern center portion to the tread end side, while extending over a width of 80% or more of the tread ground contact width, the pitch of this steeply inclined groove in the tire circumferential direction is almost twice that of the gently inclined groove, In addition, the groove width of the steeply inclined groove is Pneumatic tires that are equal to or better than that. 2. The pneumatic tire according to claim 1, wherein the flatness is in the range of 30 to 65%. 3. The pneumatic tire according to claim 1, wherein the steep grooves located on each side of the pattern center are arranged so as to be offset from each other in the tire circumferential direction. 4. The negative ratio within the ground plane is 35 to 45.
The pneumatic tire according to any one of claims 1 to 3, which is in the range of%. 5. The pneumatic tire according to any one of claims 1 to 4, wherein the pattern center is located at a position closer to the outside of the vehicle than the tread center of the tire mounted on the vehicle. 6. The pneumatic tire according to claim 1, wherein the pattern center is aligned with the tread center. 7. The pneumatic tire according to claim 1, wherein the groove arrangement is asymmetric with respect to the tread center. 8. The pneumatic tire according to claim 1, wherein the steeply inclined groove has a groove width wider than that of the gently inclined groove. 9. The pneumatic tire according to claim 1, wherein gently sloping grooves extending on each side of the pattern center are continuous on the pattern center.