JPH06127218A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire which is excellent in on-ice performance and also excellent in hydroplaining property on wet road surface and durability on dry road surface, especially a studless tire with a block pattern for main use on ice and snow road surfaces. CONSTITUTION:A pneumatic tire is provided with multiple inverse V-shaped inclined main grooves 4 which have a top section at the center area 2 of a tread 1 and arranged in diverse arrangement from the top to both side areas 3 and multiple lateral curved grooves 6 which are extended between both side edges of the tread in recessed and crossed arrangement in the direction reverse to the diverse direction in an interval along the periphery of the tread. Also it is provided with a tread land section 7 of a block arrangement pattern which is divided by these inclined main grooves 4 and lateral curved grooves 6.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Pneumatic tires with excellent ice and snow performance, hydroplaning resistance on wet road surfaces and durability on dry road surfaces, especially for ice and snow road surfaces. A studless tire having a pattern.

[0002]

2. Description of the Related Art Conventionally, spiked tires have been used for icy and snowy road surfaces because they have a high icy and snowy performance due to their spike effects. There was a problem from the above. A studless tire was developed to solve this problem.

Studless tires do not have metal spikes on the tread. Therefore, this tire can be provided with ice and snow performance by using soft rubber which is made somewhat soft as the material of tread rubber, formation of a block pattern on the tread, formation of plural sipes on the land portion of the tread, and the like. Even on the road surface, it is possible to drive without damaging the road surface.

The studless tire is not limited to the case where the actual use environment is generally only on the snow and snow road surface, but there are cases where the ice and snow road surface and the wet road surface or the dry road surface are mixed, and the studless tire has satisfactory performance even in such a case. , For example, it is required to have good drainage property on wet road surface, good durability on dry road surface, etc., and it is becoming popular as a so-called all-weather tire, and recently, higher ice and snow performance is required for this tire. It started to come.

Conventional studless tires generally have a tread having a block pattern (FIG. 5) in which circumferential grooves, lateral grooves, and sipes are arranged, as disclosed in Japanese Patent Publication No. 3-23367.

[0006]

[Problems to be Solved by the Invention] However, Japanese Patent Publication No. 3-2
The studless tire having the block pattern as disclosed in Japanese Patent No. 3367 has excellent ice and snow performance, but has insufficient performance on a wet road surface and a dry road surface.

A drawback of the studless tire is that step wear occurs during running.
Therefore, it is important to suppress the occurrence and progress of this wear because it extends the service life of the tire.

Therefore, an object of the present invention is to improve the driving / braking property and the cornering property of snow and snow on the surface of ice and snow by improving the tread pattern, and also to improve the hydroplaning resistance on wet road surface and the durability on dry road surface. Is to improve.

[0009]

SUMMARY OF THE INVENTION The present invention has a top in the central region of the tread at intervals along the circumference of the tread,
A large number of inverted V-shaped inclined main grooves arranged in a divergent array extending from the top toward both sides and a curved intersection array of concaves in the reverse direction to the divergent direction with respect to these inclined main grooves, extending between both side edges of the tread. A pneumatic tire having a large number of transverse curved grooves, and a tread land portion having a block array pattern defined by the inclined main grooves and the transverse curved grooves. Further, in the region where the inclined main groove covers 60 to 90% of the tread half width on both sides of the equator of the tire, the inclination angle is 15 to 40 ° with respect to the plane including the equator, and the remaining lateral regions have the same or more equal value. The cross-curved groove has a groove edge corresponding to the ground contact side boundary shape of the tire, and the cross-curved groove has a width of 50 to 200 of the tread width in an area covering at least 50% of the tread width. More preferably, it is an arcuate curve with a radius corresponding to%.

An example of a pneumatic tire according to the present invention is shown in FIG.
The footprint of this tire is shown in FIG. Figure 1
In the drawing, 1 is a tread, 2 is a central region, 3 is a lateral region, 4 is an inclined main groove, 5 is an equator of a tire, 6 is a transverse curved groove, and 7 is a tread land portion. The central region 2 referred to here is a region that covers 50% of the tread half width on both sides of the tire equatorial plane, and the lateral region 3 is a region that covers 10 to 40% of the tread half width from each tread edge. An intermediate region exists between the central region 2 and the lateral regions 3.

The pneumatic tire of the present invention has a large number of inverted V-shapes having a top portion in the central region 2 of the tread 1 at intervals along the circumference of the tread and having a divergent arrangement from the top portion to both side regions 3. The inclined main groove 4 is provided.

The tops of the inclined main grooves 4 are located within 50% of the tread half width on both sides of the equator 5 of the tire, and the inclined main grooves 4 extending from the apex toward both sides are,
In the region of 60 to 90% of the tread half width, 15 to 40 ° with respect to the plane including the equator 5, preferably 2
It is preferable that the inclination angle is 0 to 30 °, and the remaining lateral region 3 has an inclination angle equal to or greater than that of the central region 2, preferably 25 to 35 °. If the inclination angle of the inclined main groove 4 in the central region 2 is less than 15 °, the edge effect against lateral force is large, but the drainage performance on a wet road surface deteriorates. If it exceeds 40 °, the edge in the tire circumferential direction is increased. The component is reduced, and as a result, the edge effect on the lateral force is reduced,
This is because the cornering property deteriorates, and both side areas 3
The reason why the inclination angle is equal to or greater than that of the central area 2 is for prompt drainage. From the viewpoint of preventing step wear, it is preferable that the ends of the inclined main grooves 4 communicate with the transverse curved grooves 6, respectively.

Since the tire of the present invention has an inverted V-shaped inclined main groove instead of the circumferential groove, the ground contact pressure distribution in the tread width direction becomes flatter, so that the amount of step wear in the tread width direction of each block. Can be reduced and the service life of the tire can be extended. There may be a case where the vertical groove 12 is provided on the extension of the top end of the inclined main groove 4, but this is achieved by increasing the land edge component along the circumferential direction of the central region 2.
This is for further improving the cornering characteristics. Further, since it is sufficient that this apex is in the central region, this apex may be arranged offset from the equator 5 as shown in FIG.

The tire is also provided with a large number of transverse curved grooves 6 extending between both side edges of the tread in a curved intersection arrangement of concaves in the inclined main groove 4 in the direction opposite to the diverging direction thereof. And a tread land portion 7 having a block arrangement pattern divided by the transverse curved groove 6. The negative rate on the tread surface is 25 to 55%, preferably 35 to 45%.

It is preferable that the transverse curved groove 6 has a groove edge corresponding to the shape of the boundary 8 on the ground contact side of the tire, and particularly in a region covering at least 50% of the tread width, it corresponds to 50 to 200% of the tread width. It is more preferable that the radius is arcuate. As a result, the following three effects are obtained.

1. Since the landing area on the stepping side of the land portion can be made large, the frictional resistance of the tread surface becomes high, and the effect of improving the grounding performance can be obtained. 2. Since the tread tread is easily deformed when touching down, it is easy to eliminate the snow caught in the transverse curved groove when kicking the road surface. 3. The edge effect at the time of stepping is increased by making the edge of the block approximately coincide with the boundary on the side where the tire touches the ground.

[0017]

The pneumatic tire of the present invention has a large number of inverted V-shaped inclined main grooves when used on an icy and snowy road surface, so that the edge effect against lateral force is great, cornering property is excellent, and transverse curved grooves are formed. By forming the curved shape corresponding to the tire ground contact side, it is possible to improve the ground contact property by increasing the ground contact area, improve the ability to remove bitten snow, and obtain a high edge effect. Further, when used on a wet road surface, the inclined main groove allows water to be promptly removed to the outside of the front side of the tire even when traveling at high speed. Further, by having an inverted V-shaped inclined main groove instead of the circumferential groove, the contact pressure distribution in the tread width direction becomes flatter, so that the amount of step wear in the tread width direction of each block can be reduced and the tire The service life can be extended.

[0018]

Example A pneumatic tire having a tire size of 185 / 70R13, a tread width of 150 mm, and a negative ratio (total groove area / total tread surface area) on the tread surface of 42% was used as a test tire. The structure other than the tread has a known structure.

◎ Test tire Fig. 4 shows an example of a typical tread pattern of the tire of the present invention.
FIG. 5 shows a conventional tire.

The arrangement angle α on each side of the inclined main groove was set to 26 ° with respect to the tread center circumferential line. Further, the ends of the inclined main grooves 4 extending from the apex to the lateral regions 3 respectively communicate with the transverse curved groove 6 at a position of 80% of the tread width, and the vertical groove 12 is provided at the tip of the apex of the inclined main groove 4. have. In addition,
The above-mentioned arrangement angle of the inclined main groove 4 is preferably increased from the top toward the lateral region 3. The transverse curved groove 6 has a center point on the equator and has an arcuate arrangement shape with a radius of 115 mm. At least in the central region 2, this shape approximately coincides with the tire contact-ground depression side boundary 8.

There are six types of tread land portions: block a, block b, block c, block d, block e and block f. Further, in the embodiment, 5 or 6 sipes and the sipes that divide the sipes are arranged along the transverse curved groove in each land portion of the tread according to the convention, but this may be omitted.

The conventional tire used in the conventional example has the same structure as the invention tire except that it has the tread pattern shown in FIG.

◎ Test method The test is carried out on a test course under conditions where the tire internal pressure is 1.8 kgf / cm ² and the load on the tire is equivalent to the actual vehicle (2 people), and the starting acceleration performance on the snowy road surface, braking performance and The cornering performance, the starting acceleration performance and the braking performance on an icy road surface, the hydroplaning resistance on a wet road surface, and the step wear amount on a dry road surface were measured and evaluated. Here, the snow-covered road surface is a snow-covered road surface, and the icy road surface is a general road surface. In the start acceleration test, the time from starting to passing the 50 m point was measured and evaluated. Brake performance test is 40km / h
The braking distance from was measured and evaluated. In the cornering test, a circle was made on a snowy road surface, and the cornering property at that time was evaluated. Hydroplaning resistance test is 8 per hour
The remaining ground contact area of the tire when running 0 km was measured and evaluated. In the step wear test, the step amount of the block after running 10,000 km was measured and evaluated.

◎ Test results Table 1 shows the results of the above tests. In all the tests, the numerical values in the table are index ratios with the conventional example being 100, and the larger the value, the better the performance.

[0025]

[Table 1]

From these test results, it can be seen that the tire of the present invention is excellent in all the performances tested.

[0027]

EFFECTS OF THE INVENTION According to the present invention, by having an inverted V-shaped inclined main groove and a transverse curved groove, driving / braking performance and cornering performance are excellent on ice and snow road surfaces, and high drainage performance on wet road surfaces. The hydroplaning phenomenon is unlikely to occur, and the amount of step wear of the block can be reduced on a dry road surface, so that the service life of the tire can be extended. From the above, the tire of the present invention not only exhibits excellent performance on ice and snow road surfaces, but also exhibits good performance on wet and dry road surfaces, and thus can be used as an all-weather tire.

[Brief description of drawings]

FIG. 1 is an overall view of a main part of a tread portion of a typical invention tire developed.

2 is a footprint of the invention tire shown in FIG. 1 (a pattern on a road surface as viewed from above). FIG.

FIG. 3 is an overall plan view of a main portion of a tread portion of an inventive tire used in Examples.

FIG. 4 is an overall plan view of a main portion of a tread portion of an invention tire having a tread pattern in which a top position of an inclined main groove is displaced from a central circumferential line.

FIG. 5 is a conventional tire having the same structure as the invention tire except for the structure of the tread pattern.

[Explanation of symbols]

 1 tread 2 central area 3 lateral area 4 inclined main groove 5 tire equator 6 transverse bending groove 7 tread land area 8 step-in side boundary 9 kick-out side boundary 10 tread edge 11 sipe 12 vertical groove r tire rotation direction p Direction of travel S Area of contact W Tread width L Inclination between the top of the main groove and the center line α Arrangement angle

Claims (4)

[Claims] 1. A large number of inverted V-shaped inclined main grooves having a top portion in the central region of the tread at a distance along the circumference of the tread and forming a divergent array from this top portion to both side regions, and these inclined main grooves. A large number of transverse curved grooves extending between both side edges of the tread in a concave curved intersection arrangement opposite to the diverging direction of the grooves are provided, and a block arrangement pattern defined by these inclined main grooves and transverse curved grooves is formed. Pneumatic tire with a tread land portion. 2. The inclined main groove has an inclination angle of 15 to 40 ° with respect to a plane including the equator in a region covering 60 to 90% of the tread half width on both sides of the equator of the tire, and in the remaining lateral regions. The pneumatic tire according to claim 1, which has an inclination angle equal to or greater than the same. 3. The pneumatic tire according to claim 1, wherein the transversely curved groove has a groove edge corresponding to the boundary shape of the tire on the ground contact side. 4. The transverse curved groove has at least 5 of the tread width.
The pneumatic tire according to claim 1, 2 or 3, which has an arcuate curvature with a radius corresponding to 50 to 200% of the tread width in a region of 0%.