JPH05338415A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a tire devised to secure excellent wet performce, to have high surface gripping force at the time of high speed turning travel and to improve deflected abrasion resistance. CONSTITUTION:This is a pneumatic tire provided with a groove 2 in the peripheral direction and a groove in the cross direction extending diagonally upward. The groove 3 in the cross direction is constituted of a rectilineal or curved first groove 4 continuously extending at a comparatively large angle in the tread peripheral direction and a second groove 5 extending roughly in parallel with the first groove 4 at a part in the neighbourhood of a tread end and at a part in the neighbourhood of the groove 2 in the peripheral direction, it is divided into a central block 10 and two pieces of roughly quadrangle corner blocks 11, 12, and groove width of a central part 8 of the second groove 2 is made to be width enough for facing groove walls to make contact with each other against work of large force in the tread cross direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, especially when it is used for daily driving, it can be safely driven under any weather, and when it is used for limit driving on a circuit or the like. In addition, the present invention relates to a tread pattern capable of traveling stably under a high road surface grip force and effectively preventing occurrence of uneven wear.

[0002]

2. Description of the Related Art Conventional tires, which are generally called high grip tires, extend substantially in the circumferential direction of the tread.
There are many ones having a so-called straight pattern, which is a combination of five circumferential grooves and widthwise grooves. Among them, in recent years, in order to improve the wet performance of the tire, each widthwise groove is In a front view of a tire mounted on a vehicle, a straight unidirectional pattern in which a tire rotation direction is specified by extending diagonally upward from a tread center toward a tread end is mainstream.

[0003]

By the way, in the straight unidirectional pattern in which the circumferential groove and the widthwise groove are combined, both the hydroplaning resistance in the straight running and the turning running on the wet road surface are obtained. In order to improve it, a relatively wide linear circumferential groove is often provided at a position approximately half the tread half width from the tread edge. Due to load movement, input from the road surface to the tire, etc., the shoulder block row on the tread end side of the linear circumferential groove will be deformed relatively greatly, and the road surface grip force of the tire will decrease due to the start of the deformation. , By running for a long time,
There is a problem that particularly large uneven wear occurs in each of the shoulder block row on the outside of the turning and the send block row adjacent to the inside of the shoulder block row.

As a countermeasure against such uneven wear, it is effective to narrow the groove width of the linear circumferential groove to reduce the negative ratio, but this reduces wet performance. Since it is difficult to secure safety in general use, it has been strongly desired to establish a technology capable of achieving both anti-uniform wear resistance and wet performance, which are contradictory to each other, at a high level. The present invention provides a pneumatic tire that advantageously solves the problems of the prior art.

[0005]

According to the pneumatic tire of the present invention, each tread half area is provided with at least one circumferential groove extending substantially in the circumferential direction of the tread, and
In the tread half area, a plurality of widthwise grooves that are opened in each of the tread end and the circumferential groove are provided, and each of these widthwise grooves is viewed from the front of the tire in a mounting posture on the vehicle. It is one that extends obliquely upward from the tread central area toward the tread end, and the widthwise groove has a relatively large angle with respect to the tread circumferential direction, for example,
A linear or curved first groove that continuously extends at an angle of 50 to 80 °, and extends substantially parallel to the first groove in each of the tread end vicinity portion and the circumferential groove vicinity portion, Between these parts, at least one first groove is formed to intersect with a second groove, and the second groove is divided between the tread end and the circumferential groove and adjacent to each other. A substantially quadrilateral land portion formed by a second groove, and a central block extending diagonally of the land portion,
The central block is divided into two substantially quadrilateral corner blocks located at the corners of the land, and further, at least the central portion of the second groove intersecting the first groove is divided. The groove width is such that the opposing groove walls can contact each other against the action of a large force in the tread width direction.

Preferably, the groove width of at least the central portion of the second groove which intersects with the first groove is set to such a width that the opposed groove walls do not contact each other when the tire rolls straight forward.
Further, preferably, the width from the tread end to the edge of the circumferential groove is in the range of 50 to 85% of the tread half width, and further, the groove width of the circumferential groove is the same as the groove width of the first groove. 120-25
The range is 0%.

[0007]

In this pneumatic tire, the water on the road surface taken into the circumferential groove is quickly discharged to the side of the tire by the first groove extending at a relatively large angle with respect to the circumferential direction of the tread. In addition to that, since it forms a large angle with respect to the tread circumferential direction, it is possible to sufficiently enhance the block rigidity against the force in the tread width direction and effectively prevent the occurrence of uneven wear.

Further, according to the second groove of the tire, in the circumferential direction of the tire, the central portion of the tire intersects with the first groove, in other words, the portion forming a small angle with respect to the circumferential direction of the tread. The drainage efficiency can be increased to almost the same level as the ditch, and the central part and the first
The wet performance can be further improved by branching the drainage passing through the central portion into the first groove based on the intersection with the groove of (1) and shortening the flow distance of the drainage.

In addition, the second groove tends to form a substantially parallelogram-shaped land portion defined between the first grooves adjacent to each other between the tread end and the circumferential groove. By partitioning into a central block extending in the angular direction and two corner blocks of a substantially quadrilateral shape that are located at the corners of the land part by separating the central block, together with improvement in wet performance and ground contact, The rigidity of each block is made uniform with respect to the force in each direction.

Further, here, the width of at least the central portion of the second groove is set to, for example, 80 to 100% of the groove width of the other portion of the second groove, and the action of a large force in the width direction of the tread. On the other hand, by allowing the opposing groove walls to come into contact with each other, the three blocks can be brought into contact with each other integrally at the time of high-speed turning, so that the drainage can be ensured as in the conventional example. As compared with the case of providing a wide linear groove in the circumferential direction, the grip force on the road surface can be sufficiently increased, and the risk of uneven wear can be removed very effectively.

In addition, in this tire, the second groove extends substantially parallel to the first groove in each of the tread end vicinity portion and the circumferential groove vicinity portion, so that the second groove is formed. It is possible to prevent an acute-angled corner portion from being generated in the divided block, and effectively avoid uneven wear of the block. By the way, by setting the groove width of the central portion of the second groove to such a width that the groove walls do not come into contact with each other when the tire rolls straight under load, it is possible to sufficiently secure the wet performance for general running of the vehicle. ..

The width from the tread edge to the groove edge of the circumferential groove is 50 to 85% of the tread width, more preferably 65 to 75%.
By setting it in the range of%, it is possible to partition the block having appropriate rigidity. That is, if it is less than 50%, each block becomes too small to secure the required rigidity, and if it exceeds 85%, the block becomes large and the rigidity becomes too high, so the action of external force The deformation of the block with respect to is small, and the groove wall of the second groove cannot be brought into contact with each other. As a result, uneven wear of the block may occur.

Further, when the groove width of the circumferential groove is set to be in the range of 120 to 250% of that of the first groove, excellent wet performance, in particular, hydroplaning resistance can be secured. it can. That is, assuming that the first groove has a groove width (about 4 to 7 mm) as a general lug groove, the wet performance can be improved by setting the contrast ratio in the range of 120 to 250%. It can be well balanced with the rigidity and wear resistance of the blocks on both sides. In other words, if it is less than 120%, the groove width of the circumferential groove becomes narrower and the drainage property is lowered, and hydroplaning phenomenon and the like are likely to occur. Conversely, if it exceeds 250%, the wet performance is improved. However, since the negative ratio for the ground contact width of the tire becomes too large and it becomes impossible to secure block rigidity in the cross-sectional direction, grip performance declines, and
Uneven wear and early wear are likely to occur. In addition, in this tire, when the second grooves, which are located adjacent to each other, in particular, the central portions thereof are positioned so as to overlap each other in the circumferential direction of the tread, regardless of the ground contact position of the tread, The central portion always extends over the entire length of the ground contact length, which can ensure substantially the same drainage performance as the conventional circumferential groove.

[0014]

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. The tire size is 205/60 R15, the tread width is 228 mm, and the groove negative ratio is 34.2%. Here, the tread tread 1 is on both sides of the tread center xx. The respective linear circumferential grooves 2 and 2 are provided symmetrically with respect to each other, and the respective circumferential grooves 2 are provided.
The width of the groove is set to 11.0 mm, and a plurality of widthwise grooves 3 which are opened in the tread end and the linear circumferential groove 2 are provided at predetermined intervals in the tread circumferential direction in each tread half area. Are provided and their respective widthwise grooves 3 are
In the front view as shown, of the tire in the mounting posture on the vehicle,
Gradually extend diagonally upward from the tread center area toward the tread edge.

Here, the widthwise groove 3 is composed of a first groove 4 extending continuously in a curved line in the figure, and a second groove 5 extending in combination with the first groove 4 by bending. That is, the first groove 4 extends at a relatively large angle with respect to the circumferential direction of the tread, for example, an angle in the range of 50 to 80 °, and opens in the tread end and the circumferential groove 2, respectively. The first groove 4 here forms an angle of 65 ° with the tire circumferential direction. The groove width of the first groove 4 is from 8.5 mm to 5.0 mm as it approaches the tread center xx from the tread edge.
It gradually decreases to mm.

And, this is also the second groove 5 which is opened in each of the tread end and the circumferential groove, more precisely,
The second groove 5 extending from the tread end to the tread center xx is made to extend substantially parallel to the first groove 4 in each of the tread end vicinity portion and the circumferential groove vicinity portion, Between the parts, one first groove 4 is crossed and extended. This second groove 5 in the illustrated example is an end portion 6 on the tread end side, forms an angle of 65 ° with the tread circumferential direction, has a groove width of 7.5 mm, and has an end on the tread center side. 65 with respect to the tread circumferential direction in part 7
Has a groove width of 5.0 mm with an angle of °, and at the central portion 8 intersecting the first groove 4, forms an angle of 16 ° with respect to the circumferential direction of the tread and has a groove width of 4.0 mm. Have.

As a result, between the tread end and the circumferential groove 2, a substantially parallelogram-shaped land portion 9 partitioned between the first grooves adjacent to each other is formed. It is divided into a central block 10 which is bent substantially in a stepwise direction and extends, and two rectangular blocks 11 and 12 of substantially quadrilateral shape which are located at the corners of the land portion 9 and are separated from each other by the central block 10. ..

The width W ₀ from the tread end to the groove edge of the circumferential groove 2 is 69.5% of the tread half width W, and the pitch P of the widthwise grooves 3 is 70 mm. Incidentally, in the above-mentioned place, the groove width (11.0 mm) of the circumferential groove 2 is in the range of 130 to 220% of the groove width (5.0 to 8.5 mm) of the first groove 4.

According to the pneumatic tire constructed as described above, the width direction groove 3 can bring about the above-mentioned effects, and the excellent wet performance can be ensured. It is possible to sufficiently enhance the road surface grip force during high-speed turning travel, and to effectively prevent uneven wear on the tires.

Although the present invention has been described above based on the illustrated example, it is also possible to provide a plurality of circumferential grooves in a plurality of three or more.

(Comparative Example) A comparative test between the inventive tire and the conventional tire regarding steering stability on dry and wet road surfaces, hydroplaning resistance and uneven wear will be described below.

◎ Test tire ・ Invention tire A tire having a tread pattern shown in Fig. 1. Conventional tire having a tread pattern shown in FIG. 2,
A tire having the same size, rubber and the like as the invention tire except that the circumferential groove has a groove width of 9 mm and the widthwise groove has a groove width of 5 to 7 mm.

◎ Test method A tire filled with the internal pressure specified by JIS is mounted on an actual vehicle, and under the load condition of two passengers (70% load specified by JIS), the steering stability on a dry road surface is The driver's feeling when driving on a dry circuit was evaluated, and the steering stability on wet road surface was 5
The hydroplaning resistance was evaluated at the depth of water of 5 mm by evaluating the feeling when driving on the limit of the wet comprehensive road of mm.
A photograph was taken of the ground contact surface of the tire when traveling at 100 km / h on the mm measurement path, and the ground contact area of the pattern was measured to obtain and evaluate the area ratio of the actual ground contact area. After running the circuit for 30 minutes to the limit, the step wear that occurred was measured and evaluated by calculating the sum ratio.

◎ Test Results The results of the above tests are shown in Table 1 as index values using the conventional tire as a control. It should be noted that the index value indicates a better result as the index value is larger, excluding uneven wear.

[0025]

[Table 1] As shown in Table 1, it is apparent that the invention tire can effectively improve both the steering stability on dry road surface and the uneven wear resistance while keeping the wet performance sufficiently high.

[0026]

As described above, according to the present invention, it is possible to always ensure safe and stable running on dry and wet road surfaces during general running, and at the circuit etc. It is possible to ensure high stability and effectively prevent the occurrence of uneven wear during the limit travel of the vehicle under excellent road surface gripping force.

[Brief description of drawings]

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

FIG. 2 is a tread pattern showing a conventional example.

[Explanation of symbols]

 1 tread tread 2 circumferential groove 3 widthwise groove 4 first groove 5 second groove 6,7 end portion 8 center portion 9 land portion 10 center block 11, 12 corner block W tread half width P pitch xx Tread center

Claims (4)

[Claims] 1. Each tread half area is provided with at least one circumferential groove extending substantially circumferentially of the tread, and the tread half area is provided with an open groove in each of the tread end and said circumferential groove. A plurality of widthwise grooves are provided, and each of these widthwise grooves extends in a diagonally upward direction from the center area of the tread toward the tread end in a front view of the tire in a mounting position on the vehicle. A tire, wherein the widthwise groove is a linear or curved first groove that continuously extends at a relatively large angle with respect to the tread circumferential direction, and a tread end vicinity portion and a circumferential groove vicinity portion, respectively. Part of the first groove and the second groove which extends substantially parallel to the first groove and intersects at least one first groove between these parts. Next to each other The substantially quadrilateral shaped land portion divided between the first grooves is formed by the second groove, and a diagonally extending central block of the land portion is separated from the central block by the second groove. It is divided into two substantially quadrilateral corner blocks located at the corners, and the groove width of at least the central portion of the second groove intersecting the first groove is set to a large force in the tread width direction. A pneumatic tire having a width that allows the opposing groove walls to come into contact with each other against the action. 2. The air according to claim 1, wherein a groove width of at least a central portion of the second groove intersecting with the first groove is set such that the groove walls do not come into contact with each other when the tire rolls straight forward. Included tires. 3. The pneumatic tire according to claim 1, wherein the width from the tread end to the groove edge of the circumferential groove is in the range of 50 to 85% of the tread half width. 4. The groove width of the circumferential groove is set to 12 times the groove width of the first groove.
The pneumatic tire according to any one of claims 1 to 3, which has a range of 0 to 250%.