JPH08207515A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To allow a tire to send out an alarm when the groove depth has reached a certain limit due to progress of wear by providing on the groove bottom of a tire equipped with a tread consisting of a plurality of low protrusions on its groove bottom at intervals with similar low protrusions at intervals and forming a pocket having its circumference closed between both low protrusions. CONSTITUTION: A tread 1 is provided with, at regular intervals, numbers of main grooves, which incline with respect to the equatorial surface 0 in the shape of the figure 8 from the position near the equatorial surface 0, extend near a tread ground end Ec keeping their wide width, from where they change their directions towards the axis by narrowing their width, and end at a tread Et after turning around in a hook-shape, and the similar land parts in the shape of the figure 8 are divided, airs of protrusions protruding from respective groove bottoms are provided in a narrow groove 2n of 3mm width and pockets are formed with their circumference closed between the protrusions. By providing pairs of low protrusions on the groove bottom of the tread at mutual intervals of 10 to 20mm and forming pockets between the protrusions, pumping noise is heard at the terminal stage of wear and a driver is informed of tire exchange.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which gives an alarm when a tread reaches a wear limit by running.

[0002]

2. Description of the Related Art As a pneumatic tire travels and the tread wears, the various properties of the tire usually change in the direction of deterioration, especially when the wet skid resistance is significantly deteriorated. Wear limit is displayed by the wear indicator. Wear indicator
The turret is the bottom of the groove engraved on the tread, which is partially raised around the circumference of about 1.8 mm at about 6 places, and when the wear of the tread reaches the surface position of this wear indicator, the residual groove depth is reached. Is 1.8 mm, and suggests replacement of tires.

[Problems to be Solved by the Invention]

In order to know the wear state based on the wear indicator, a visual check is necessary, but a general driver is less interested in the tires mounted on the vehicle and the check is performed. Even if you feel the need to change tires, you often forget about it except when you can do it immediately. Most of the accidents caused by slips that occur frequently in the rain are caused by running that cannot control the wear state of tires. The present invention has been made in view of the above problems, and an object thereof is to provide a pneumatic tire that issues a warning to the driver each time the vehicle travels, when the depth of the groove provided in the tread reaches a certain limit due to wear. To do.

[0004]

The present invention provides a tire having a tread including a plurality of grooves and a land portion divided by the grooves, the tread having a plurality of small raised ridges spaced at the bottom of the groove. With the above-mentioned ridge on the groove bottom of the tread
A pneumatic tire having a similar second ridge at a distance of 20 mm and forming a closed pocket between the ridges.

The depth of the pockets is 1 to 3 mm, and the pockets are arranged in the shoulder portions of the tread at 25 to 35 mm.
It is preferable that they are provided at substantially equal intervals on the individual circumference.

[0006]

The tire according to the present invention is provided with a plurality of pockets on the circumference of which the circumference is closed by a pair of raised ridges spaced apart at the bottom of the groove that divides the land portion in the tread and both land portions. Therefore, when the land of the tread wears to the surface position of the ridge, the pocket that has stepped on the ground contact surface during traveling is isolated from the flow of the groove and the internal air is compressed. Is ejected, and the pumping sound as an alarm is repeated. Tread pattern that normally produces the pumping sound
In order to distinguish it from noise, it is necessary to set the ridge spacing to 10
It is necessary to set it to -20 mm.

The depth of the pockets of 1 to 3 mm is a value that means a substantial wear life, and the pockets are arranged at 25 shoulder portions of the tread where the ground contact pressure increases after the wear progresses.
By providing about 35 pieces at substantially equal intervals on the circumference, it is possible to obtain a more effective pumping sound.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A description will be given below with reference to the drawings. FIG. 1 is a partial plan view of a tread showing an embodiment of a tire according to the present invention,
2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a sectional view taken along the line BB. The tire according to the present invention includes a plurality of grooves 2 and a land portion 3 divided by these grooves, and a tread 1 having a plurality of small raised ridges 5 on a bottom 4 of the groove 2. And when the above-mentioned ridge provided in the groove bottom of the tread and the first ridge 5 _1, a second ridge 5 ₂ similar at a distance i for 10~20mm from the raised 5 _1, both raised 5 _1, 5 ₂ It forms a closed pocket 6 between them.

Although not shown in the drawings, the tire according to the present invention is assumed to have a pair of side walls and a crown portion connected in a toroidal manner across both side walls by a conventional method, and one side wall is crowned. For example, a radial arc can be arranged between the portion and the other side wall, and the non-stretchable belt layer and the tread 1 shown in the figure can be arranged on the outer periphery of the crown portion of the carcass for reinforcement. In this case, the radial arc is made of polyester,
This is a known structure composed of at least one ply, usually two plies in which fiber cords represented by Yong are arranged in a direction substantially orthogonal to the equatorial plane O, and the belt layer is also a steel cord or the like. A plurality of plies in which the non-stretchable cords of No. 1 are inclined at a shallow angle (15 to 35 °) with respect to the equatorial plane O, usually two, are stacked so that the cords cross each other.
Further, it is a known structure including a cap layer formed by circumferentially spirally winding a rubberized strip in which a plurality of heat-shrinkable cords such as nylon are lined up around the entire periphery thereof. Although the left side of the equator O is omitted in FIG. 1, it is symmetrical.

FIG. 1 shows an example of a tread of a flat radial tire for passenger cars of 225 / 50ZR16 size. In this embodiment, the tread 1 is inclined from the position near the equatorial plane O to the equatorial plane in a figure eight shape. It extends in a wide width near the tread ground contact end E _C (ground contact end when driving straight ahead), changes the width from this position in the direction of the diaphragm axis, and finally reverses into a hook shape and ends at the tread end E _T. The main groove 2 _M is provided at a predetermined interval, and the same 8-shaped land portion 3 is divided.

The land portion 3 further includes two sipes (0.7 mm).
Width) 7 and a narrow groove 2 _N near the ground contact end E _C to subdivide the small land portion or block 3 _B. In the block 3 _B on the grounded end, which is broadly divided in the circumferential direction in relation to the direction and width of the main groove 2 _M , the thin groove 2 _N intersects with the narrow groove 2 _N in a T-shape and extends substantially parallel to the main groove 2 _M. A lug groove 8 similar to 2 _N is provided, and it is divided into two in the circumferential direction while leaving a part.

In this embodiment, a pair of ridges 5 projecting from the groove bottom 4 is provided in each of the narrow grooves 2 _N having a width k of 3 mm, and a pocket 6 having a closed circumference is formed between them. In this example, the first and second ridges 5 ₁ and 5 ₂ facing the main groove 2 _M both protrude at a height h of 1.5 mm, and the distance i between them is 15 to 2
It is 0 mm. In this example, the lug groove 8 with a width j of 3 mm is a narrow groove 2 _N
Since it is necessary to close the side surface of the pocket 6 due to the opening to the bottom, the third ridge 5 ₃ is provided on the groove bottom 4 facing the narrow groove 2 _N with the same height m as the first and second ridges. . Even not a set third ridge 5 ₃ always in contact with the thin groove 2 _N, place the required distance from the narrow groove, also the height m also first and second ridge height h
It is possible to place it higher.

The pocket 6 is formed on the tread at a distance (ground width) 30 from the left and right ground ends E _C to the ground ends.
Preference is given to a shoulder area corresponding to%. In the case of this example, it is at the position of 13%.

The arrangement of the pockets 6 is not limited to the narrow groove, but may be provided in the main groove. However, in the case of a tire having a flat cross section as in this example, since the tread has a wide width and a flat shape, the arrangement of the ridges on the wide groove bottom for pocket formation impairs drainage. There is a risk that it is not preferable.

The groove in which the pocket 6 is provided needs to have a width that does not close during traveling. For example, even if a pocket is provided in the sipe 7 having an extremely narrow width such as a cut, a pumping noise may occur during traveling, but it cannot be distinguished from pattern noise or the like.

[0016]

[Effect] To confirm the effect of the tire according to the present invention, 225 /
50ZR16 size Between the tire of the above-mentioned example and the tire of the same comparative example except that no pocket is provided in the narrow groove (thus no ridge 5) A pumping sound (warning sound) generation test was performed in an actual vehicle and evaluated.

In the test, the tire of the example was worn until the raised upper surface appeared, and the tire of the comparative example was similarly worn, and the tire was assembled on a 16 × 8J rim and 2.0 kgf / cm
After adjusting the internal pressure to ² , it was mounted on a vehicle and the sound when traveling on an asphalt road at a normal speed (45 to 55 km / H) was evaluated by the driver's feeling. As a result, in the case of the tires of the comparative examples, naturally no noise other than pattern noise and road noise was generated, whereas the tires of the examples were clearly different from these noises or sounds. I was able to hear the sound caused by such pumping.

Thus, 10 to 20 are formed on the bottom of the groove of the tread.
mm The tire of the present invention having a pair of raised ridges spaced apart from each other and having pockets formed therebetween, informs the driver that tire replacement has occurred at the end of wear.
It gives a clear warning sound.

[Brief description of drawings]

FIG. 1 is a plan view of a tread of a tire according to an embodiment.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG.

[Explanation of symbols]

 1 Tread 2 Groove 3 Land 4 Groove bottom 5 Raised 6 Pocket

Claims (3)

[Claims] 1. A tire having a tread including a plurality of grooves and a land portion divided by the grooves, the tread having a plurality of small raised ridges at intervals on the bottom of the groove, wherein the ridge is formed on the groove bottom of the tread. A pneumatic tire having similar second ridges spaced 10 to 20 mm apart and forming a closed pocket between the ridges. 2. The pneumatic tire according to claim 1, wherein the pocket has a depth of 1 to 3 mm. 3. The shoulders of the tread are provided with the pockets.
The pneumatic tire according to claim 1 or 2, wherein 25 to 35 pieces are provided in the portion at substantially equal intervals.