JP2014156190A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of reducing wear difference between a center part rib and a shoulder rib.SOLUTION: A tire 1 comprises: plural circumferential grooves 3 disposed so as to extend along a tire circumferential direction on a tread surface 2 of the tire 1; plural ribs 4,5 divided by the plural circumferential grooves on the tread surface of the tire; and sipings 6 disposed so as to traverse the center part rib 5 other than the pair of shoulder ribs 4, 4 disposed on end sides of the tire width direction among the plural ribs in the tire width direction. The sipings 6 have depth equal to or more than 70% of groove depth of the circumferential grooves, and the number of the sipings disposed on one center part rib on a ground surface of the tread surface during load applying time is 7 or more and 14 or less.

Description

  The present invention relates to a tire provided with a plurality of ribs extending on a tread surface in a direction along the tire circumference (hereinafter referred to as a tire circumferential direction).

  A tire having a plurality of ribs defined by a plurality of circumferential grooves provided so as to extend in the circumferential direction of the tire is known.

JP 2001-55013 A

In the tire described above, on the tread surface, a pair of shoulder ribs provided on both end sides in a direction along the tire rotation center line (hereinafter referred to as tire width direction), and a center portion other than the shoulder rib In order to wear the ribs as uniformly as possible, it is conceivable to control the ground contact shape under load, that is, the contact length of the shoulder rib with respect to the contact length of the center rib. In this case, if the contact length of the shoulder rib is too short compared to the contact length of the center rib, the shoulder rib is more affected by wear caused by dragging when the tire rolls, and the shoulder rib and the center rib are separated. Does not wear evenly. For this reason, it is conceivable to aim for uniform wear by controlling the ground contact shape so that the contact length of the shoulder rib and the contact length of the center portion rib are equal.
However, when the tire is new, uniform wear can be aimed at by the above-mentioned contact shape control, but since the tire grows in a non-uniform diameter by running, the contact shape easily changes from the new time. There is a problem in that the effect of controlling the grounding shape is reduced during the use.
The present invention provides a tire that can reduce the difference in wear between a center rib and a shoulder rib in order to solve the above problems.

The tire according to the present invention includes a plurality of circumferential grooves provided on the tire tread surface so as to extend along the tire circumferential direction, and a plurality of circumferential grooves defined on the tire tread surface by the plurality of circumferential grooves. A rib and a sipe provided on a center part rib other than the pair of shoulder ribs provided on both ends in the tire width direction of the plurality of ribs so as to cross the center part rib in the tire width direction. The sipe has a depth of 70% or more of the depth of the circumferential groove, and the number of the sipe provided on one center portion rib in the ground contact surface of the tread surface when a load is applied is 7 Since the center portion rib is finely divided by the sipe and the ground pressure of the center portion rib can be lowered and the rigidity of the center portion rib can be lowered, since the number is 14 or more and less than the number, it is separated by the sipe. The tread deformation when kicking per similar, one-block can equivalent to the tread deformation when kicking of the shoulder rib can be reduced wear difference between the center ribs and the shoulder ribs.
If the shoulder rib has a sipe or groove having a depth of 25% or less of the depth of the circumferential groove, the rib rigidity of the shoulder rib can be secured and the ground pressure of the shoulder rib will not be lowered. The wear difference reduction effect that can reduce the wear difference between the part rib and the shoulder rib is not disturbed.
If the shoulder rib has no sipe or groove, the rib rigidity of the shoulder rib can be secured and the contact pressure of the shoulder rib does not decrease, so that the difference in wear between the center portion rib and the shoulder rib can be reduced.
Since the spacing between sipes provided adjacent to the center rib in the circumferential direction of the tire is in the range of 11.8 mm to 23.6 mm, the difference in wear between the center rib and the shoulder rib can be reduced. .

The top view which shows a tread pattern (Embodiment 1). The table | surface which showed the experimental result of the tire performance test. The top view which shows a tread pattern (Embodiment 2). A cross-sectional view of a sipe with a shallow groove. The top view which shows a tread pattern (Embodiment 3).

Embodiment 1
FIG. 1 is a diagram showing a tread surface of a tire, and a region surrounded by an imaginary line (two-dot chain line) in FIG. 1 is a state in which a load load corresponding to a vehicle load is applied to the tire 1 (that is, a load application). The contact surface A of the tread surface 2 is shown. The above-mentioned ground contact surface A of the tread surface 2 is a state where the tread tread when the tire 1 is mounted on a regular rim and the tire 1 is filled with a regular internal pressure and a regular load is applied is the ground surface. This is the surface that contacts the ground. Here, the “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA and a “Design Rim” for TRA. Or, for ETRTO, it means "Measuring Rim". The above "regular internal pressure" is the air pressure specified by the above standard for each tire. The maximum air pressure described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" is the maximum air pressure for JATMA and TRA for TRA. If it is ETRTO, it is "INFLATION PRESSURE". The “regular load” is the load specified by the above standard for each tire. If it is JATMA, it is the maximum load capacity, and if it is TRA, it is the maximum described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”. If the value is ETRTO, it is "LOAD CAPACITY".
As shown in FIG. 1, the tire 1 according to the first embodiment includes a plurality of circumferential grooves 3 provided on the tread surface 2 so as to extend along the circumferential direction of the tire 1, and a plurality of circumferential grooves 3. A plurality of circumferential ribs 4; Each of the circumferential grooves 3 and each of the circumferential ribs 4; 5 is configured to be continuously provided on the tread surface 2 so as to make one round of the circular outer circumferential surface of the tire 1, that is, centering on the rotation center line of the tire 1. It is formed in an endless circular ring shape.
Of the plurality of circumferential ribs 4; 5, a pair of shoulder ribs 4 provided on both end sides in the tire width direction; a plurality of ribs 5 other than 4, that is, a plurality of ribs 5 located on the center side in the tire width direction on the tread surface 2 Each center rib 5; 5; 5 includes a sipe 6 provided to cross the center rib 5 in the tire width direction.
And a pair of shoulder ribs 4; 4 was set as the structure which is not provided with the groove | channel called the sipe 6 or a hot water groove. In addition, the above-mentioned hot water groove has a groove width wider than the groove width of the sipe 6 and narrower than the groove width of the circumferential groove 3, and the groove depth from the tread surface 2 is less than the sipe 6 and the groove width. The groove is configured to have a groove depth that is shallower than the groove depth of the circumferential groove 3 and is, for example, 50% or less of the groove depth of the circumferential groove 3.

The sipe 6 has a depth of 70% or more of the groove depth of the circumferential groove 3, and is provided on one center rib 5 in the ground contact surface A of the tread surface 2 when the load is applied. The number (hereinafter referred to as “the number of sipes in the ground plane”) was 7 or more and 14 or less.
The depth of the sipe 6 and the depth of the circumferential groove 3 are the depths from the surface of the center rib 5.

According to the tire 1 having the tread surface 2 configured as described above, the center rib 5 is finely divided by the sipe 6, so that the ground pressure of the center rib 5 can be reduced and the rigidity of the center rib 5 can be reduced. Therefore, the tread deformation at the time of kicking out per pseudo block divided by the sipe 6 is equivalent to the tread deformation at the time of kicking out the shoulder rib 4, and the difference in wear between the center rib 5 and the shoulder rib 4 is reduced. It is possible to provide the tire 1 that can reduce the wear difference reduction effect.
If the number of sipes in the ground plane is 6 or less, the rigidity of the center rib 5 becomes too high and the deformation amount of the center rib 5 becomes small, and it becomes difficult to obtain the effect of reducing the wear difference. Moreover, when the number of sipes in the ground plane is 15 or more, the noise performance is deteriorated.
Further, since the pair of shoulder ribs 4; 4 does not include the sipe 6 or the groove, the rib rigidity of the shoulder rib 4 can be secured and the contact pressure of the shoulder rib 4 does not decrease. The wear difference can be reduced.

The experimental result which verified the effect of the tire 1 of Embodiment 1 is shown in FIG.
In FIG. 2, load is a load applied to the tire, an internal pressure is the tire internal pressure, and a sipe interval is a separation interval between sipes provided adjacent to one center rib 5 in the circumferential direction of the tire 1. The I / W index is an index indicating the uneven wear resistance of the shoulder rib. The wear work amount is calculated from the circumferential shear force measured by the treading observation machine and the slip amount in the circumferential direction. The I / W index of the tire 1 of Experimental Example 1 is set to 100, and the larger the value, the better and the difference in wear difference can be obtained.
As can be seen from FIG. 2, when the shape / OTD is 82% and the number of sipes in the ground plane is 8 to 12, the I / W index is large and the wear difference reduction effect is obtained. .
That is, under the same condition that the shape / OTD is 82%, it is recognized that the I / W index becomes 150 or more by setting the number of sipes in the ground plane to 7 to 15, especially in the ground plane. It was confirmed that the number of sipes was 8 to 12, and the I / W index was 400, which was effective.
Further, when the shape / OTD was 67%, even if the number of sipes in the ground plane was 8, the I / W index was 100, and a remarkable effect was not obtained.
Further, under the same condition that the number of sipes in the ground plane is 8 and the sipe interval is 20.6, when the shape / OTD is 67%, 70%, 82%, and 100%, the I / I increases as the size / OTD increases. It was observed that the W index increased. From this, it was found that increasing the size / OTD contributed to the effect of reducing the wear difference.
Further, it was found that if the sipe interval is set within the range of 11.8 mm to 23.6 mm, the effect of reducing the wear difference can be obtained.
That is, from the experimental results, the shape / OTD was set to 70% or more, the number of sipes in the ground plane was set to 7 or more and 14 or less, and the sipe interval was set within the range of 11.8 mm to 23.6 mm. It has been found that a tire can be obtained that has the effect of reducing the wear difference and does not deteriorate the noise performance.

Embodiment 2
As shown in FIG. 3, drainage performance is improved by providing a grooved sipe 10 in which a groove 12 called a hot water groove is arranged on the tread surface portion of the sipe 11 in consideration of drainage on a wet road surface.
As shown in FIG. 4, the grooved sipe 10 has a groove 12 having a depth D2 shallower than the groove depth of the circumferential groove 3 from the tread surface (tread surface) of the center rib 5 in the tire width direction. The sipe 11 is formed so as to cross the groove 12 from the bottom surface 14 of the groove 12. The groove width W2 of the groove 12 is wider than the groove width W1 of the sipe 11. Also in this case, the depth D1 from the tread surface of the center rib 5 to the bottom surface of the sipe 11 is formed to be 70% or more of the groove depth of the circumferential groove 3.
However, when all the sipes are sipe 10 with a groove, the groove volume is increased, so that the noise is increased. Therefore, as shown in FIG. 3, high drainage performance can be achieved without deteriorating noise performance by alternately arranging grooved sipes 10 and grooveless sipes 11 in the center rib 5 along the circumferential direction of the tire 1. The tire 1 possessed can be obtained.

  Further, as shown in FIG. 3, a sipe 11 provided on each center portion rib 5 and extending across the center portion rib 5 in the tire width direction is provided so as to extend in the circumferential direction of the tire 1. By adopting such a configuration, the sipe 11 gradually crosses the ground contact end when stepping out and kicking out, and it is possible to suppress deterioration in noise performance due to multiple sipes. For example, as shown in FIG. 3, the effect can be obtained by providing a sipe 11 that curves in the circumferential direction of the tire.

  Also, as shown in FIG. 3, the shoulder ribs 4; 4 are configured to include a sipe 21 having a depth of 25% or less of the depth of the circumferential groove 3 or a groove called a hot water groove outside the figure. Since the rib rigidity of the shoulder rib 4 can be ensured and the contact pressure of the shoulder rib 4 is not lowered, the wear difference reducing effect that can reduce the wear difference between the center portion rib 5 and the shoulder rib 4 is not disturbed.

Embodiment 3
Furthermore, as shown in FIG. 5, a sipe 31 that extends in the circumferential direction of the tire 1 and includes a bent portion 41 is provided on the center rib 5. In particular, by providing a sipe 31 provided with a bent portion 41 so as to reciprocate in the circumferential direction of the tire 1, the front and rear blocks (front and rear in the tire circumferential direction defined by the sipe 31) can be applied to both the left and right inputs. Therefore, the tire 1 having higher steering stability can be provided.
Further, as shown in FIG. 5, the grooved sipe 32 and the grooveless sipe 31 in which grooves 12 called hot water grooves are disposed on the tread portion of the sipe 31 are alternately disposed on the center rib 5 along the tire circumferential direction. Thus, the tire 1 having high drainage performance can be obtained without deteriorating the noise performance.

  As shown in FIG. 5, a grooved sipe 35 extending in the tire circumferential direction and a grooved sipe 35 extending in the tire circumferential direction are curved in a 45 degree direction from the end of the grooved sipe 35. If the mixing groove sipe 33 provided with the groove 36 provided to extend is provided, the edge component is increased and the drainage in the rib is also improved, so that the contact property on the wet road surface is improved. A tire 1 having the same can be obtained.

  In addition, although not shown in the figure, the sipe width near the bottom of the sipe groove is made larger than the sipe width on the tread surface side of the sipe and the groove bottom of the sipe is formed with a smooth curve, thereby generating cracks by arranging deep sipe. Can be suppressed.

  In the present invention, sipe refers to a minimum width groove formed by placing a thin plate on a mold for forming a tread pattern on a tread surface, and the groove width is about 0.5 mm to 2.5 mm. Is a groove that appears as if the walls of the tread are in contact with each other and the line is on the tread surface. On the other hand, the circumferential grooves and grooves are grooves formed by convex portions formed on a mold for forming a tread pattern on the tread surface, and the groove width is about 5 mm to 2.5 mm. It is a groove that is separated from each other so that the concave portion of the groove can be confirmed.

1 tire, 2 tread surface, 3 circumferential groove, 4 shoulder rib,
5 Center part rib, 6; 11; 31 Sipe.

Claims (4)

A plurality of circumferential grooves provided on the tire tread surface so as to extend along the circumferential direction of the tire, a plurality of ribs partitioned by the plurality of circumferential grooves on the tire tread surface, and the plurality of ribs A center part rib other than a pair of shoulder ribs provided on both ends in the tire width direction, and a sipe provided to cross the center part rib in the tire width direction,
The sipe has a depth of 70% or more of the groove depth of the circumferential groove, and the number of the sipe provided on one center portion rib in the ground contact surface of the tread surface when a load is applied is 7 or more. A tire having 14 or less.   The tire according to claim 1, wherein the shoulder rib includes a sipe or a groove having a depth of 25% or less of the depth of the circumferential groove.   The tire according to claim 1, wherein the shoulder rib does not include a sipe or a groove.   The spacing distance between sipes provided adjacent to the center rib in the circumferential direction of the tire is within a range of 11.8 mm to 23.6 mm. The tire according to one item.

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