JPH05169919A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic radial tire which is reduced in pattern noise, side force arising in running and steering deviation CONSTITUTION:On the shoulder of a tread, separate blocks A, B are alternately formed with a main groove 1 extended to a tire peripheral direction and lug grooves 2 extended to a tire cross direction. The lug groove 2 has an angle of less than 90 deg. to the tire peripheral direction. The block A has the grounding width W greater than the grounding length L, while the block B has the grounding width outside end located to the tire equator side of the grounding width outside end of the block A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire in which lateral noise generated during running is reduced while reducing pattern noise.

[0002]

2. Description of the Related Art In recent years, various problems have been pointed out in pneumatic radial tires due to the directionality of the tread pattern. One of them is steering wheel flow due to lateral force generated during traveling. The magnitude of this lateral force is influenced by the tire structure such as the belt tension direction, and
Particularly, when the block row is arranged on the shoulder portion, it is affected by the lug groove angle and the block shape. That is, when the lug grooves in both shoulders are inclined in the same direction with respect to the tire circumferential direction, a lateral force is generated during traveling, and the lateral force increases as the inclination angle decreases. If the long side direction of the block is arranged along the tire width direction, the force generated in the surface direction when the block is compressed and deformed in the vertical direction has a lateral component (lateral force) rather than a tire circumferential component. growing. Therefore, when the vehicle travels with the hand released from the steering wheel, the tire flows in the direction of large lateral force (steering wheel flow).

[0003]

However, if the shoulder lug groove is designed in the radial direction in order to reduce the lateral force during traveling and the lug groove angle with respect to the tire circumferential direction is increased, pattern noise increases. For this reason,
It has been difficult to achieve both reduction of lateral force and reduction of pattern noise.

An object of the present invention is to provide a pneumatic radial tire capable of reducing pattern noise and lateral force generated during traveling to reduce steering wheel flow amount.

[0005]

A pneumatic radial tire according to the present invention has a main groove in the tire circumferential direction on a shoulder portion of a tread surface, and an inclination from the main groove toward the shoulder end with respect to the tire circumferential direction. In a pneumatic radial tire in which a lug groove is provided and a block row having a block ground contact width W larger than a block ground contact length L is formed, a block A in which the block ground contact width W is larger than the block ground contact length L, It is characterized in that blocks B having outer ends of the ground contact width are alternately arranged on the tire equator side of the outer ends of the ground contact width of the block A.

The structure of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, blocks A and B are alternately divided and formed in the shoulder portion of the tread surface by a main groove 1 extending in the tire circumferential direction and a lug groove 2 extending in the tire width direction. The lug groove 2 has a lug groove angle of less than 90 ° with respect to the tire circumferential direction. As shown in FIG. 2, the block A has a block ground contact width W larger than the block ground contact length L, and the block B has a ground contact width outer end portion on the tire equator side with respect to the block A contact outer width portion. There is. The block ground contact width W of the block A is the maximum ground contact width when grounded at 80% of the JATMA maximum load under JATMA standard air pressure. In addition, in the present invention, a block or a rib may be appropriately provided in the center portion between both shoulder portions of the tread surface.

According to the present invention, the outer end of the ground contact width of the block B is located closer to the tire equator side than the outer end of the ground contact width of the block A so that the shoulder ground contact end lines are alternately grounded inside and outside. Take dimensions. Therefore, even if the lateral force in the block A in which the long side direction is arranged along the tire width direction is large, the lateral force in the block B alternately arranged with the block A can be reduced.
It is possible to reduce the amount of steering wheel flow during traveling. Further, since the lug groove angle of the lug groove 2 with respect to the tire circumferential direction can be made small as necessary, pattern noise does not increase as the lateral force decreases.

Incidentally, by reducing the contact width of the entire shoulder block as in the block B, the lateral force generated during traveling can be reduced. Steering stability and wear resistance are significantly reduced. Therefore, by arranging the blocks A and B alternately, the lateral force reducing effect and other running performance can be satisfied at the same time. In the present invention, it is desirable that the area S _A of the block _A and the area S _{B of the} block B be the same as much as possible.
S _B / S _A is preferably 0.90 to 1.10. This is because if the surface pressures of blocks A and B are significantly different,
This is because uneven wear occurs during traveling.

[0009]

EXAMPLE A tire of the present invention having a tire size of 265 / 70R15 and a shoulder block on the tread surface arranged as shown in FIG. 1 and a conventional tire arranged as shown in FIG. 3 were manufactured. With respect to these tires of the present invention and conventional tires, the lateral force and the handle flow amount were measured by the following methods, and the results are shown in Table 1.

Lateral force: A drum test was conducted on a test tire to measure the lateral force generated during rotation, and the lateral force was expressed as an index with the value of a conventional tire being 100. The smaller this index value, the smaller the lateral force. Steering wheel flow rate: A test tire was mounted on a passenger car, an actual vehicle test was conducted, and the steering wheel flow rate during straight running was measured, and this was shown as an index with the value of a conventional tire being 100. The smaller the index value, the smaller the handle flow amount.

[0011] As is clear from Table 1, the tire of the present invention has a smaller lateral force generated during traveling than the conventional tire and the steering wheel flow amount during actual vehicle traveling was small.

[0012]

As described above, according to the present invention, in the shoulder portion of the tread surface, the block A having the block ground contact width W larger than the block ground contact length L and the outer end portion of the ground contact width of the block A are provided. Also, since the blocks B having the outer ends of the ground contact width are alternately arranged on the tire equator side, it is possible to reduce the lateral force generated during traveling and reduce the steering wheel flow amount. Moreover, since the lug groove angle with respect to the tire circumferential direction can be made small as necessary, pattern noise will not increase.

[Brief description of drawings]

FIG. 1 is a development view showing a tread surface of a pneumatic radial tire according to the present invention.

FIG. 2 is a partially enlarged view showing a shoulder block of FIG. 1 extracted.

FIG. 3 is a development view showing a tread surface of a conventional pneumatic radial tire.

[Explanation of sign]

 1 main groove 2 lug groove A, B block W block grounding width L block grounding length

Claims (1)

[Claims] 1. A main groove in the tire circumferential direction and a lug groove inclined from the main groove toward the shoulder end with respect to the tire circumferential direction are provided in a shoulder portion of the tread surface, and a block ground contact width W is a block ground contact length. In a pneumatic radial tire forming a block row having blocks larger than L, a block A having a block ground contact width W larger than a block ground contact length L, and a tire equator side of a ground contact width outer end portion of the block A. A pneumatic radial tire in which blocks B having outer ends of the ground contact width are alternately arranged.