JPH09188109A - Pneumatic tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for heavy load which is excellent in the wet-performance, and low noisy, and which has a directional pattern. SOLUTION: Main grooves 5a, 5b extending from both tread ends 2a, 2b and terminating in land parts in the neighborhood of an equatorial line 4, are arranged in a tread part 1. The main grooves extend from terminal positions 6a, 6b up to joint-positions 7a, 7b with a curvature which is gradually increased along the groove extending direction, and the main grooves have arrangement- configurations which extend in the range of 70 to 90 degrees until they extend from the joint-positions 7a, 7b and then open to the tread ends 2a, 2b. Further, auxiliary grooves 9a to 9e, both ends of which open into the two main grooves 5a, 5b, are arranged along the main grooves at certain intervals, in the area equivalent to 70 to 80% of the tread width around the equatorial line 4. Furthermore, in a tire-ground contact area 10 formed under the condition of specified air pressure and specified load, the auxiliary grooves 9a to 9e are arranged at cross-angles θ ranging from 10 to 40 degrees to the preceding ground contact side contour line 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy duty pneumatic tire having good wet performance and low noise.

[0002]

2. Description of the Related Art Treads of heavy duty pneumatic tires used for trucks, buses, etc., which are used for running on good roads with relatively few irregularities such as paved roads, have a plurality of treads along the tire circumference. The rib-shaped land portion is formed by arranging the main groove of the above, or the block-shaped land portion is formed by arranging the main groove and an auxiliary groove extending in the tire width direction across the main groove. Is.

Tires having a rib pattern are generally
It is generally used in areas where there is no snow in winter, and the tire having a block pattern is used for all seasons that can be used in areas where there is much snow in winter.

[0004]

A tire having a rib pattern has good steering stability on a dry road surface and tire noise is not a serious problem, but on the other hand, it does not have a steering stability on a wet road surface. It has a drawback that the wet performance is not sufficient. That is, the wet performance is mainly to prevent water from entering the contact area between the tire tread and the road surface, and even if water enters the contact area, it is promptly discharged from the contact area to the outside, Depends on whether or not a sufficient area to directly contact the road surface (hereinafter referred to as "actual ground contact area") can be secured without water intervention, but in the case of this tire, the drainage capacity to the front and side of the tire is low. , Water tends to infiltrate into the contact area, and some of the infiltrated water is discharged to the rear of the tire, but the discharge efficiency is low, so it is discharged to the trailing ground side of the contact area (the tire traveling direction side). Water that could not be kept was accumulated and the actual ground contact area could not be secured enough, which deteriorated the wet performance.

Further, since the tire having the block pattern is provided with the auxiliary groove in addition to the main groove, the water that has infiltrated into the contact area is discharged by the amount that is also discharged in the tire width direction by the auxiliary groove. As the performance increases, the edge component increases due to the provision of the auxiliary groove, and the driving / braking performance on a wet road surface also improves. However, since the auxiliary groove is generally regularly arranged along the tire width direction,
In the contact area of the tire formed under the conditions of specified air pressure and specified load, the contour line on the preceding ground contact side tends to match the auxiliary groove, and as a result, the ground pressure of the block end facing the auxiliary groove It has a drawback that the total amount becomes maximum and the block hammering sound becomes loud and the tire noise becomes loud.

Therefore, an object of the present invention is to form a directional pattern in which a main groove and an auxiliary groove are arranged on a tread, and optimize the arrangement shape and the arrangement angle of the main groove and the auxiliary groove. It is to develop a heavy-duty pneumatic tire with excellent wet performance and low noise.

[0007]

In order to achieve the above object, the present invention provides a pair of main treads which extend from both tread ends toward the tire equator so as to converge in the land portion near the tire equator. The grooves are arranged at intervals along the tire circumference, and the main grooves form a directional pattern that sequentially enters the tire contact area from the end to the tread end, and the main grooves are drawn to this. The intersection angle between the tangent line and the tire equatorial plane extends from the end position to the seam position within the range of 65 to 80% of the tread half width from the tire equatorial line with a gradually increasing curvature in that direction, and the seam position To an opening at the tread end, the shape has an arrangement shape that extends in the range of 70 to 90 °, and further, within the region of 70 to 80% of the tread width centered on the tire equator, Auxiliary with both ends open in the main groove Are arranged at intervals along the main groove, and in the contact area of the tire formed under the conditions of specified air pressure and specified load, in the range of 10 to 40 ° with respect to the tangent line drawn to the preceding grounding side contour line. Is a heavy-duty pneumatic tire characterized by arranging auxiliary grooves at an intersection angle of.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a part of a tread portion of a typical heavy duty pneumatic tire according to the present invention in a developed state. FIG. 2 shows the tire of FIG. 1 is an enlarged view of a part of a tire grounding portion (A in FIG. 1) when the tire is grounded under conditions, where reference numeral 1 is a tread portion, 2a and 2b are tread ends, and 3 is a tire. Rotation direction, 4 is a tire equator, 5a and 5b are main grooves, 6a and 6b are main groove end positions, 7a and 7b are main groove joint positions, 8 is a sipe, 9a, 9b, 9c, 9
2 and 9e are auxiliary grooves, reference numeral 10 in FIG. 2 is a contour line of the tire contact area, and 11 is a leading ground contact side contour line of the tire contact area.

The tire having the tread pattern shown in FIG. 1 extends in the tread portion 1 from both tread ends 2a and 2b in a direction converging to the tire equator 4 respectively.
A pair of main grooves 5a, 5b terminating in a land portion near the main groove 5a or 5b are arranged at intervals along the tire circumference.
Form a directional pattern that sequentially enters the tire contact area 10 from the end position 6a or 6b toward the tread end 2a or 2b (the tire rotation direction 3 is downward in FIG. 1).

The main groove 5a or 5b has a tangent line m drawn to it.
And the tire equatorial plane 4 have an intersection angle α of the end position 6a or 6
The distance from b to the tire equator 4 is 1/2 the tread half width
Seam position 7a or 7b in the range of 65 to 80% of W
Up to 70 ° to 90 ° from the seam position 7a or 7b to the tread end 2a or 2b. End position 6a or 6b of the main groove 5a or 5b
In order to improve drainage efficiency, it is preferable to dispose the main groove in the portion from to the seam position 7a or 7b so that the intersection angle α is in the range of 15 to 35 °. Further, the intersection angle α of the portion from the seam position 7a or 7b to the opening to the tread end 2a or 2b is set in the range of 70 to 90 °. If the angle is less than 70 °, the shoulder block end becomes an acute angle, and the same. This is because the rigidity difference in the block becomes large and a core of uneven wear is likely to occur.

Further, within a region of 70 to 80% of the tread width W centered on the tire equator 4, a plurality of auxiliary grooves 9a, 9b, 9c, 9d, 9 having both ends open to two main grooves.
The tire contact area 1 in which e are arranged at intervals along the tire circumference, and these auxiliary grooves 9a to 9e (specifically, the center lines of the auxiliary grooves) are formed under the conditions of specified air pressure and specified load.
It is arranged at an intersection angle θ in the range of 10 to 40 ° with respect to the leading ground side contour line 11 of 0. The intersection angle θ between the auxiliary grooves 9a to 9e and the preceding grounding side contour line 11 is set in the range of 10 to 40 ° as shown in FIG. 3 when the intersection angle θ is 10 ° or more. Is significantly reduced, and when it exceeds 40 °, the sound pressure level tends to increase. Although the auxiliary groove is arranged in a crank shape in the drawing, it may be linear or curved and can be appropriately changed.

In FIG. 1, the main grooves 5a and 5b are displaced from each other by a half pitch, and the main grooves 5a and 5b are terminated in the land so as not to communicate with each other. 5b may be arranged in line symmetry with the tire equator as an axis, or main grooves 6a and 6b forming a pair based on the tire circumference slightly displaced from the tire equator in the tire width direction may be arranged. The main grooves 6a and 6b may communicate with each other. Further, in FIG. 1, the crank groove 13 branched from the seam position of the main groove and extending in a crank shape along the tire circumference and opening to the adjacent main groove is arranged to secure the shoulder edge component. The crank groove 13 may be provided as needed.

[0013]

EXAMPLE A specific example of the pneumatic tire according to the present invention will be described with reference to FIG. -Examples The heavy duty pneumatic tires used in the examples have the tread pattern shown in Fig. 1, and the tire size is TBR11.
R22.5 14PR, and the tread portion 1 is provided with a pair of main grooves 5a, 5b extending in a direction in which the tread ends 2a, 2b converge to the tire equator 4 and terminating in a land portion near the tire equator 4 in a tire circle. The tires are arranged at intervals along the circumference, and the main groove 5a or 5b extends from the end position 6a or 6b toward the tread end 2a or 2b.
A directional pattern that sequentially enters inside is formed. Main groove 5a
Or 5b, the intersection angle α between the tangent line m drawn to this and the tire equatorial plane 4 is from the end position 6a or 6b to the seam position 7a.
Or up to 7b, the end position 6a or 6b is extended by 15 ° and the seam position 7a or 7b is gradually increased by 30 °, and the tread end 2 is extended from the seam position 7a or 7b.
It was extended at 80 ° until opening to a or 2b.

The main grooves 5a and 5b are arranged so as to be displaced from each other by a half pitch (33 mm), and furthermore, the main grooves 5a and 5b are terminated in the land portion so as not to communicate with each other. The main groove has a groove depth of 16.5 mm and a groove width of 5 at the end position 6a or 6b.
mm, 9 mm at seam position 7a or 7b, tread end 2
It was 8 mm at the a or 2b position.

Further, in a region of 70 to 80% of the tread width W centered on the tire equator 4, both ends are opened to two main grooves, and a crank-shaped auxiliary groove 9a having a groove width of 6 mm,
9b, 9c, 9d and 9e were arranged at intervals along the tire circumference. These auxiliary grooves 9a to 9e are 10 to 40 ° with respect to the tangent line n drawn to the preceding grounding side contour line 11 of the tire contact area 10 formed under the conditions of the specified air pressure and the specified load.
It was arranged so that the intersection angle would be.

Further, at the edge of the block facing the main groove, two or three sipes 8 each having a width of 1.0 mm, a depth of 15 mm and a length of 2 mm are provided in order to suppress uneven wear nucleation due to side force. Arranged. In addition, a crank groove 13 that is branched from the seam position of the main groove and extends in a crank shape along the circumference of the tire and opens to an adjacent main groove is provided. The carcass
It consists of one ply of a rubberized layer in which steel cords are radially arranged, and the belt is two in the middle of the tire circumference.
The layer is composed of four cord rubberized layers each having a 72 ° cross-laminated arrangement, and other tire structures are almost the same as the conventional tire.

Conventional Example 1 The tire used in Conventional Example 1 is a conventional tire having a rib-based pattern shown in FIG. Conventional Example 2 The tire used in Conventional Example 2 is a conventional tire having a mixed pattern of blocks and lugs shown in FIG. 7.

Test method In the test, the above test tire was used to evaluate the wet performance and the tire noise. The wet performance was evaluated by measuring the coefficient of friction when traveling on a road surface in rainy weather and changing the traveling speed. The tire noise was evaluated by measuring the noise level when running on a dry road surface and changing the running speed. The evaluation results are shown in FIGS. 4 and 5, respectively. From these results, the example was superior to the conventional examples 1 and 2 in the wet performance and the tire noise was small.

[0019]

According to the present invention, most of the water existing in front of the tire extends from the end position of the main groove to the seam position with a gradually increasing curvature in that direction.
Through this main groove part, water can be smoothly removed from the center part of the tread toward the shoulder side to the front side of the tire, and water that has not been completely removed and has entered the contact area can pass through the main groove from the ground contact center area to the ground contact side. It can be discharged toward the area promptly, the actual ground contact area can be secured, and the drainage performance is improved.

Further, by extending the main groove from the seam position to the opening at the tread end in the range of 70 to 90 °, the driving / braking performance in rainy weather is improved. Furthermore, 70-80 of tread width centering on the tire equator
%, By arranging two main grooves with auxiliary grooves whose both ends are open at intervals along the main groove, it is possible to improve driving / braking performance during rainy weather traveling. , The auxiliary groove is formed in the contact area of the tire which is formed under the condition of the specified air pressure and the specified load, with respect to the contour line on the preceding ground contact side,
By arranging at a crossing angle in the range of 40 °, the block land portion partitioned by the main groove and the auxiliary groove is gradually grounded without locally increasing the ground pressure of the block end portion facing the auxiliary groove. As a result, the block hammering sound is reduced.

From the above, according to the present invention, it is possible to provide a heavy-duty pneumatic tire having excellent wet performance and low tire noise, which could not be achieved by a conventional tire having a rib pattern or a block pattern. .

[Brief description of the drawings]

FIG. 1 is a developed view of a part of a tread portion of a typical pneumatic tire for heavy load according to the present invention.

FIG. 2 is an enlarged view of a part of a ground contact portion (A in FIG. 1) of a tire formed under conditions of specified air pressure and specified load.

FIG. 3 is a graph showing the sound pressure level measured when the crossing angle θ of the auxiliary groove on the leading ground side 11 of the tire contact area 10 formed under the conditions of the specified air pressure and the specified load is changed from 0 to 90 °. FIG.

FIG. 4 is a diagram showing the results of measuring the coefficient of friction values when the running speed was changed for each test tire.

FIG. 5 is a diagram showing the results of measuring the noise level when the running speed is changed for each test tire.

FIG. 6 is a conventional tire having a rib pattern used in Conventional Example 1.

FIG. 7 is a conventional tire having a rib pattern used in Conventional Example 2.

[Explanation of symbols]

 1 tread portion 2a, 2b tread end 3 tire rotation direction 4 tire equator (plane) 5a, 5b main groove 6a, 6b end position of main groove 7a, 7b seam position of main groove 8 sipes 9a, 9b, 9c, 9d, 9e Auxiliary groove 10 Contour line of tire contact area 11 Leading contact side contour line of tire contact area 13 Crank groove m Tangent line drawn on main groove α Crossing angle between tangent line m drawn on main groove and tire equatorial plane 4 W tread width

Claims (1)

[Claims] 1. A pair of main grooves extending from both tread ends in a direction converging to the tire equator and terminating in a land portion in the vicinity of the tire equator are arranged in the tread portion at intervals along the tire circumference, In a heavy-duty pneumatic tire in which a main groove forms a directional pattern that sequentially enters the tire contact area from the end to the tread end, the main groove has a tangent line (m) drawn to this and a tire equatorial plane. The intersection angle (α) with and from the end position to the seam position within the range of 65 to 80% of the tread half width from the tire equator extends with a gradually increasing curvature in that direction, and from the seam position to the tread end. It has an arrangement shape that extends in the range of 70 to 90 ° until it opens in the area of 70% to 80% of the tread width centered on the tire equator. Main groove is an auxiliary groove with both ends open 10 to 40 ° with respect to the contour line on the preceding ground side in the contact area of the tires that are arranged at intervals along
A heavy-duty pneumatic tire characterized in that an auxiliary groove is arranged at an intersection angle (θ) in the range.