WO2010122805A1 - Pnuematic tire - Google Patents

Abstract

Provided is a pneumatic tire used with a negative camber having enhanced driving and braking capability on icy surfaces while maintaining steering stability on a dry road surface. Provided are a circumferential shoulder groove (3) and a plurality of transverse grooves extending from the circumferential shoulder groove (3) to a tread edge at each of lateral ends of the tread to form an asymmetric tread pattern that includes lines of shoulder blocks (11). Each of the tread blocks is provided with circumferential thin grooves wherein the volume of the thin groove (13) at the inner side in the mounted position is greater than that of the thin groove (14) at the outer side.

Description

Pneumatic tire

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that achieves both steering stability on ice and on a dry road surface.

In conventional pneumatic tires, in order to improve the handling stability on ice, a narrow groove extending in the tread circumferential direction is provided in the tread portion, and this narrow groove increases the drag of the side skid of the tire, so that contact during cornering is possible. By increasing the biting of the narrow groove edge of the ground to the ice surface and preventing skidding, the responsiveness at the small steering angle and the limit speed at the time of turning are increased, and on wet roads and snowy roads Hydroplaning during cornering can be prevented.

However, if a narrow groove extending in the tread circumferential direction is provided, the block rigidity with respect to the input in the lateral direction is lowered, and therefore, the steering stability during cornering on a dry road surface may be lowered. .

In addition, in order to improve steering stability on the dry road surface, if the groove depth of the narrow groove in the tread circumferential direction is made shallow, steering stability on ice is lowered, while on the other hand, in order to improve on-ice performance, If the groove depth of the narrow groove is increased, the handling stability on the dry road surface will be further reduced. Therefore, the handling stability on the ice and on the dry road surface is balanced at a high level by the narrow groove extending in the tread circumferential direction. It was very difficult to do.

By the way, in recent years, in order to improve the steering stability of the vehicle, a tendency to give a negative camber to the tire is increasing. In this case, the tire extends in the tread circumferential direction to each land portion located on the outermost side of the tire. When the narrow grooves are provided with the same groove volume, the land part that will be located outside the vehicle and the land part that will be located inside will be particularly dry on ice due to the difference in contact length. It was difficult to make the functions of the narrow groove on the road surface straight and turn.

Accordingly, an object of the present invention is to improve driving and braking performance on ice without reducing steering stability on a dry road surface, particularly in a pneumatic tire to be used with a negative camber. It is to provide a pneumatic tire that can be used.

The pneumatic tire according to the present invention defines a shoulder block row by disposing a shoulder circumferential groove and a plurality of lateral grooves extending from the shoulder circumferential groove to the tread side edge on the outermost side in the tread width direction. The tread portion is formed with an asymmetric pattern, and the shoulder block rows have narrow grooves extending in the circumferential direction of the tread and are positioned on the inner side of the vehicle in a mounting position on the vehicle. The groove volume of the groove is larger than the groove volume of the narrow groove located outside the vehicle.

Here, the “groove volume of the narrow groove” is determined from the length, depth, width and number of the narrow grooves.
The groove depth is an industrial standard effective in the region where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) STANDARDDS MANUAL, In the United States, tires are assembled to rims specified in TRA (THE TIRE and RIM ASSOCIATION INC.) YEAR BOOK, etc., and the tread treads are filled with the maximum air pressure as defined by JATMA standards. The depth measured from the bottom to the groove bottom.

More preferably, in such a tire, the narrow groove is terminated in the middle of the block.
Preferably, a plurality of the fine grooves are provided, and the fine grooves are arranged so as to be offset from each other in the tread circumferential direction.

The pneumatic tire of the present invention is configured such that the groove volume of the narrow groove that is located inside the vehicle is larger than the groove volume of the narrow groove that is located outside the vehicle in a mounting posture on the vehicle. In the land part where the negative camber is applied, the lateral force is greatly applied during cornering, so the biting characteristics of the narrow groove edge of the ground contact surface to the ice surface are increased. In addition to preventing side-slip, the land portion that is located inside the vehicle is grounded mainly when traveling straight, so that it is possible to increase the response at a small steering angle and the limit speed at the time of turning. As a result, the handling stability on ice and on a dry road surface can be improved.

It is a partial development view of a tread pattern showing one embodiment of a pneumatic tire of the present invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial development view of a tread pattern showing one embodiment of the pneumatic tire of the present invention.
Since the reinforcing structure inside the tire is the same as that of a general radial tire or bias tire, illustration is omitted.

The tread pattern shown in FIG. 1 is an asymmetric pattern, and the tire shown in FIG. 1 is used in a posture in which the right side is the vehicle mounting inner side.
In the figure, 1 indicates the entire tread surface, and the tread surface 1 includes a plurality of circumferential grooves extending in the tread circumferential direction, two center circumferential grooves 2 provided with a tire equator line apart in the figure, A shoulder circumferential groove 3 adjacent to each side portion of the center circumferential groove 2 is disposed.
A central land portion 4 is partitioned between two circumferential grooves adjacent to each other, in the figure, between two center circumferential grooves 2, and an intermediate land portion 5 is defined between the center circumferential groove 2 and the shoulder circumferential groove 3. Then, each shoulder land portion 6 is defined between the shoulder circumferential groove 3 and the tread side edge.

The central land portion 4 is provided with a lateral groove 7 extending from the center circumferential groove 2 on the inner side of the vehicle inclining with respect to the tread circumferential direction and ending within the central land portion.
Further, in the intermediate land portion 5, a plurality of intermediate blocks 9 are defined by lateral grooves 8 that are inclined with respect to the tread circumferential direction and open to the center circumferential groove 2 and the shoulder circumferential groove 3.

In the shoulder land portion 6, a plurality of shoulder blocks 11 are defined by the lateral grooves 10 that are inclined with respect to the circumferential direction of the tread and extend across the shoulder land portion 6 from each of the shoulder circumferential grooves 3, and open to the tread side edge. To do.

In each of the land portions 4, 5 and 6, sipe 12 extending obliquely with respect to the tread circumferential direction is provided so as to open in the groove.

In the tread pattern shown in FIG. 1, in order to increase the rigidity of each block on the outer side of the tire with respect to the tire equator line and to suppress block deformation during cornering, the negative surface area is increased and the block surface area is increased. On the inside, the block surface area is reduced by increasing the negative rate in order to ensure drainage when wet.

In this pneumatic tire, the shoulder block 11 at the outermost side in the tread width direction is further provided with two narrow grooves extending in the tread circumferential direction and parallel to each other in the figure, and the groove volume of the narrow groove 13 on the inner side of the mounting is set as follows. It is made larger than the groove volume of the narrow groove 14 on the outside of the mounting.
In this case, preferably, the groove width of the narrow groove 13 on the inner side of mounting is 1.5 mm or less, the groove depth is 2 mm, the groove width of the narrow groove 14 on the outer side of mounting is 1.5 mm or less, and the groove depth is 1 mm. .

2 to 4 are partial development views of a tread pattern showing another embodiment of the present invention.
In addition, the same code | symbol is attached | subjected to the element similar to the tire shown in the previous figure, and the description is abbreviate | omitted.
Preferably, in this pneumatic tire, as shown in FIG. 2, the number of narrow grooves 13 on the vehicle mounting inner side is equal to or greater than the number of narrow grooves 14 on the vehicle mounting outer side. For example, the narrow grooves 13 on the vehicle mounting inner side are parallel to each other. The three extending grooves 14 on the outer side of the vehicle are two extending in parallel to each other.
By adopting this configuration, the tire with negative camber has a long contact length when traveling straight on the inside of the vehicle, so it can prevent drainage during straight travel and side slip at a small steering angle. Stiffness can be secured on the outside to counter lateral force and side slip during cornering.

Also, preferably, as shown in FIG. 3, by closing the narrow grooves 13 and 14 in the middle of the block, it is possible to suppress a decrease in the block rigidity, especially on the vehicle mounting outside where a large lateral force is applied during cornering. It is preferable to provide a narrow groove.

And preferably, a plurality of narrow grooves 13 and 14 are provided, and these narrow grooves are arranged so as to be offset from each other in the tread circumferential direction, so that the change in the rigidity of the block in the tread circumferential direction is reduced, and the grounding property is reduced. It is possible to cope with a change in rigidity while securing the above.

As shown in FIG. 4, the narrow groove 15 extending in the tread circumferential direction can be provided not only in the shoulder block 11 but also in the intermediate block 9.

Next, experimental tires, comparative tires 1 and 2 were prototyped, and as shown in Table 1, the respective characteristics were changed to improve riding comfort, dry road handling stability and wet road handling stability. evaluated.

(Ride comfort)
For each of the example tires and comparative tires 1 and 2, with a rim size of 6.5 J × 16 ST 50 and a tire pressure of 250 kPa, the golf V TDI was attached with a negative camber, and the test course was carried out by one driver + 70 kg. Then, riding comfort was evaluated by feeling, and the results are shown in Tables 2 and 3. The evaluation in Table 2 indicates that the larger the value, the better the riding comfort.

(Dry road handling stability)
For each of the example tires and comparative tires 1 and 2, with a rim size of 6.5 J × 16 ST 50 and a tire pressure of 250 kPa, the golf V TDI (2006 type) was attached with a negative camber, and the test course was , 1 driver + 70kg, dry road surface handling stability was evaluated by feeling, and the results are shown in Tables 2 and 3. The evaluation in Table 2 indicates that the larger the numerical value, the better the dry road handling stability.

(Wet road maneuvering stability)
For each of the example tires and comparative tires 1 and 2, with a rim size of 6.5 J × 16 ST 50 and a tire pressure of 250 kPa, the golf V TDI (2006 type) was attached with a negative camber, and the test course was A driver + 70 kg, the wet road surface handling stability was evaluated by feeling, and the results are shown in Tables 2 and 3. The evaluation in Table 2 indicates that wet road surface handling stability is better as the numerical value is larger.

DESCRIPTION OF SYMBOLS 1 Tread tread 2 Center circumferential groove 3 Shoulder circumferential groove 4 Central land part 5 Middle land part 6 Shoulder land part 7, 8, 10 Horizontal groove 9 Intermediate block 11 Shoulder block 12 Sipe 13 Narrow groove inside vehicle installation 14 Narrow groove outside vehicle installation Groove 15 Narrow groove

Claims (3)

By arranging a shoulder circumferential groove and a plurality of lateral grooves extending from the shoulder circumferential groove to the tread side edge on the outermost side in the tread width direction, a shoulder block row is defined to form an asymmetric pattern in the tread portion. In the pneumatic tire
The shoulder block row has narrow grooves extending in the tread circumferential direction,
A pneumatic tire characterized in that the groove volume of the narrow groove that is located inside the vehicle in a mounting posture on the vehicle is larger than the groove volume of the narrow groove that is located outside the vehicle. . The pneumatic tire according to claim 1, wherein the narrow groove ends in the middle of the block. The pneumatic tire according to claim 1 or 2, wherein a plurality of the narrow grooves are provided, and the narrow grooves are offset from each other in the tread circumferential direction.

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