JP2006062551A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making wet property and dry property compatible and preventing heel and toe wear efficiently without reducing steering stability. <P>SOLUTION: In this pneumatic tire, a lateral cross sectional channel formed in an internal region on an inner side more than an equator line of the tire when mounted in a vehicle is closed in a peripheral direction channel, a lateral cross sectional channel formed in an external region on an outer side more than the equator line of the tire when mounted in the vehicle is opened in the peripheral direction channel, width of the lateral cross sectional channel in the external region is smaller than width of the lateral cross sectional channel in the internal region, a negative rate in the internal region is 38 to 42%, and a negative rate in the external region is 30 to 34%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire having an asymmetric pattern on a tread.

Conventionally, a pneumatic tire having a tread pattern has a WET property by making the negative rate of the inner region inside the tire equator line higher than the negative rate of the outer region outside when the vehicle is mounted. Further, by making the rigidity of the block used in the outer area higher than the rigidity of the block used in the inner area, steering stability during cornering on the DRY road surface is ensured. Here, as a method of increasing the rigidity of the block, chamfering the edge of the block is known (for example, Patent Documents 1 and 2). Therefore, in order to ensure WET performance and steering stability during cornering on the DRY road surface, further improvements have been made to the negative rate in the inner region and the block rigidity in the outer region.
JP 2000-071718 A JP 2000-225811 A

  However, when the negative rate of the inner region is increased to an appropriate numerical value or more, there are problems that the portions in contact with the road surface are reduced and the burden on those portions is increased, so that wear in the tread portion is deteriorated. Further, when the rigidity of the block in the outer region is increased to an appropriate value or more, the elasticity for absorbing the impact or the like is reduced, so that there is a problem that the steering stability is lowered.

  Therefore, in view of the above problems, the present invention has an object to provide a pneumatic tire capable of reducing heel-and-toe wear without lowering steering stability while achieving both WET and DRY properties. And

  In order to solve the above-described problems, the present invention is characterized in that the tread includes at least two circumferential grooves extending in the tire circumferential direction, a central region and an end region defined by the circumferential grooves, and an end region. A cross-sectional groove that is formed and intersects at an angle of 3 ° to 10 ° with respect to the circumferential groove, and a transverse block that is defined by the intersection of the circumferential groove and the transverse groove, and the tread pattern is A pneumatic tire that is asymmetrical in the tire equator line that is the center in the tire width direction, and the cross-sectional groove formed in the inner region inside the tire equator line is closed to the circumferential groove when the vehicle is mounted, and the vehicle is mounted Sometimes the cross-sectional groove formed in the outer region outside the tire equator line opens into the circumferential groove, the width of the outer region cross-sectional groove is smaller than the width of the inner region cross-sectional groove, the inner region negative The rate is between 38% and 42% The gist of the present invention is a pneumatic tire characterized in that the negative rate of the outer region is 30% to 34%.

  According to the pneumatic tire according to the feature of the present invention, the negative rate of the inner region is set to 38% to 42% to ensure the WET property, and the negative rate of the outer region is set to 30% to 34% to ensure the DRY property. , DRY property and WET property can be made compatible. Further, by opening the cross-sectional groove of the outer region having a low negative rate in the circumferential groove in order to ensure the DRY property, the WET property of the outer region can be ensured. In addition, in order to increase the rigidity of the horizontally long block by closing the inner side cross-sectional groove with the negative rate higher than the outer region to the circumferential groove in order to ensure the WET property, to ensure the DRY property Can do. Furthermore, since the rigidity of the transverse block in the outer region is improved by making the width of the transverse groove in the outer region smaller than the width of the transverse groove in the inner region, heel-and-toe wear can be suppressed.

  Further, the chamfer radius at the edge of the circumferential cross section of the horizontally long block formed in the outer region of the pneumatic tire according to the feature of the present invention is the chamfer radius at the edge of the circumferential cross section of the horizontally long block formed in the inner region. Is preferably smaller. Since the chamfer radius at the edge of the circumferential cross section of the horizontally long block formed in the outer region is smaller than the chamfer radius at the edge of the inner region, the lateral block of the outer region that aims at steering stability during cornering on the DRY road surface The shear rigidity can be improved and the occurrence of heel and toe wear can be reduced.

  Moreover, it is preferable that ratio of the depth of the circumferential groove | channel formed in the outer area | region in the pneumatic tire which concerns on the characteristic of this invention, and the depth of a cross-sectional groove | channel is 1: 0.82-0.85. Since the ratio of the depth of the circumferential groove formed in the outer region to the depth of the transverse groove is 1: 0.82 to 0.85, the shear rigidity in the horizontally long block can be improved, and the heel and Toe wear can be suppressed.

  Moreover, it is preferable that the inclination angle of the side surface of the cross-sectional groove formed in the outer region in the pneumatic tire according to the characteristics of the present invention is greater than or equal to the inclination angle of the side surface of the cross-sectional groove in the inner region. Since the lateral cross-sectional groove side surface has an inclination and the angle of the inclination is the same in the outer region and the inner region, or the angle of the outer region is larger than the angle of the inner region, the shear rigidity of the horizontally long block in the outer region Can be further improved, and heel and toe wear can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can make WET property and DRY property compatible, and can suppress heel and toe wear, without reducing steering stability can be provided.

  Below, the tread 12 formed in the pneumatic tire 10 which concerns on this embodiment is demonstrated.

  FIG. 1 is a view showing the surface of the tread 12 in the present embodiment.

  The tread 12 is provided with a circumferential groove 14, a transverse cross-sectional groove 16, and a horizontally long block 18.

  The circumferential grooves 14 are grooves extending in the tire circumferential direction (arrow E direction), and at least two are formed. The tread 12 is partitioned into a central region C and an end region S by a circumferential groove 14. Specifically, when two circumferential grooves 14 are formed, a region including the tire equator line between the two circumferential grooves 14 is a central region C, and the two circumferential grooves 14 The outer regions 14 are end regions S. In FIG. 1, the region outside the two circumferential grooves 14 formed at the outermost end in the tire width direction (arrow F direction) is the end region S, and the region inside the two circumferential grooves 14 is inside. The region is the central region C.

  The cross-sectional groove 16 is a groove that intersects the circumferential groove 14 with an inclination of 3 ° to 10 ° and extends in the tire width direction. Further, the cross-sectional groove 16 is formed in the end region S. Further, the width H of the cross-sectional groove 16 formed in the inner region (hereinafter referred to as the IN side) that is inside when the vehicle is mounted, with the tire equator line CL being the center in the tire width direction as a boundary, It is wider than the width G of the cross-sectional groove 16 formed in the outer region (hereinafter referred to as the OUT side) that is sometimes outside.

  The horizontally long block 18 is a block defined by the circumferential groove 14 and the transverse groove 16 intersecting each other. The horizontally long block 18 is a shoulder block formed in the end region S.

  The tread 12 is divided into an IN side and an OUT side. Further, the tread pattern formed on the tread 12 is asymmetric in the tire equator line CL.

  FIG. 2 is a view showing a cross section of the tread 12 in the present embodiment.

  FIG. 2A is a diagram showing a circumferential cross section AA of the horizontally long block 18 formed on the OUT side in FIG.

  As shown in the figure, the edge portion of the circumferential cross section of the horizontally long block 18 formed on the OUT side is smoothly chamfered from the upper surface of the block toward the side surface. Further, the chamfer radius R at the edge of the circumferential cross section of the horizontally long block formed on the OUT side is smaller than the chamfer radius R of the edge of the circumferential cross section of the horizontally long block formed on the IN side.

  FIG. 2B is a view showing a cross section B-B in the width direction of the intersection between the circumferential groove 14 and the transverse groove 16 formed on the OUT side in FIG.

  As shown in the figure, when the depth Ba of the circumferential groove 14 formed on the OUT side is 1, the depth Bb of the cross-sectional groove 16 formed on the OUT side is 0.82 to 0.85. is there.

  FIG. 3 is a diagram showing a cross-section of the transverse groove 16 in the present embodiment.

  FIG. 3A is a view showing a circumferential section CC of the transverse groove 16 formed on the IN side in FIG.

  As shown in the figure, the inclination angle of the side surface of the transverse groove 16 formed on the IN side is an angle c (for example, 3 ° to 8 °).

  FIG. 3B is a view showing a circumferential section DD of the transverse section groove 16 formed on the OUT side in FIG.

  As shown in the figure, the inclination angle of the side surface of the transverse groove 16 formed on the OUT side is an angle d (for example, 5 ° to 10 °).

(Operation and effect of the pneumatic tire according to the present embodiment)
According to the pneumatic tire 10 according to the present embodiment, the negative rate on the IN side is set to 38% to 42% to ensure the WET property, and the negative rate on the OUT side is set to 30% to 34% to ensure the DRY property. , DRY property and WET property can be made compatible. Here, if the negative rate on the IN side is less than 38%, the wettability at the time of WET worsens, so the WET property decreases, and if it exceeds 42%, the surface in contact with the road surface decreases. The load on the surface is increased, and wear at the tread portion is deteriorated. Also, if the negative rate on the OUT side is less than 30%, the wettability at the time of WET worsens, so the WET property decreases. If it exceeds 34%, the rigidity of the tread portion increases, and the elasticity to absorb impacts, etc. This reduces the steering stability. Further, the OUT side WET property can also be ensured by opening the OUT side cross-sectional groove having a low negative rate in the circumferential groove to ensure the DRY property. Moreover, in order to increase the rigidity of the horizontally long block by closing the IN side cross-sectional groove whose negative rate is higher than the OUT side in order to ensure the WET property to the circumferential groove, to ensure the DRY property Can do. Furthermore, since the rigidity of the lateral block on the OUT side is improved by making the width of the lateral cross-sectional groove on the OUT side smaller than the width of the lateral cross-sectional groove on the IN side, heel and toe wear can be suppressed.

  In addition, since the chamfer radius at the edge portion of the circumferential cross section of the horizontally long block formed on the OUT side is smaller than the chamfer radius at the edge portion on the IN side, the landscape side on the OUT side that improves steering stability during cornering on the DRY road surface The shear rigidity of the block can be improved and the occurrence of heel and toe wear can be reduced.

  Moreover, since the ratio of the depth of the circumferential groove formed on the OUT side and the depth of the cross-sectional groove is 1: 0.82 to 0.85, the depth of the circumferential groove and the cross-sectional groove is different. The shear rigidity in the horizontally long block can be improved, and heel and toe wear can be suppressed. Here, when the depth of the cross-sectional groove formed on the OUT side is less than 0.82 with respect to the depth of the circumferential groove formed on the OUT side, the water drainage at the time of WET deteriorates. For this reason, when the WET property decreases and exceeds 0.85, the bottom surfaces of the circumferential grooves and the cross-sectional grooves become closer, so the shear rigidity cannot be improved, and heel-and-toe wear is effectively reduced. It becomes difficult to suppress.

  In addition, the lateral groove surface is inclined, and the angle of the inclination is the same on the IN side and OUT side, or the angle on the OUT side is larger than the IN side. It is possible to improve the heel and toe wear.

  Examples of the pneumatic tire according to the embodiment of the present invention will be described in detail below.

  As shown in Table 1, tires of Conventional Example 1, Example 1, Example 2 and Example 3 were manufactured and tested under the conditions shown below, and maneuvering on a WET road surface having a water depth of 2 mm and a DRY road surface. Stability and the state of occurrence of heel and toe wear in the laterally long block on the OUT side were examined. The conventional example 1 is the tread pattern shown in FIG. 4, the width I of the lateral cross-sectional groove on the OUT side and the width J of the lateral cross-sectional groove on the IN side are the same (both 6 mm), and the laterally long formed on the OUT side. The edge of the circumferential section of the block is not chamfered, and the depth of the transverse section groove formed on the OUT side is 0.88 when the depth of the circumferential groove formed on the OUT side is 1. there were. Note that all the tires had the same tread pattern.

  The size of the pneumatic tire was 225 / 40R18.

<Steering stability>
Based on the feeling of a professional test driver, the steering stability on the WET road surface and the DRY road surface was evaluated on a 10-point scale.

<Heal and toe wear occurrence>
The vehicle equipped with the tires was run for 10,000 km on a general road, and the amount of step difference due to the wear of the stepped part and the kicked part of the lateral block on the OUT side was investigated and evaluated.

The obtained results are also shown in Table 1.

  From the results in Table 1, Example 1, Example 2 and Example 3 suppress the heel-and-toe wear without lowering the steering stability on the DRY road surface and the WET road surface as compared with Conventional Example 1. I understood. Specifically, it has been found that heel and toe wear is suppressed in order to improve the shear rigidity of the horizontally long block by chamfering the edge of the circumferential cross section of the horizontally long block formed on the OUT side. Further, the shear in the horizontally long block is also obtained when the depth of the cross-sectional groove formed on the OUT side when the depth of the circumferential groove formed on the OUT side is 1 is 0.82 to 0.85. It has been found to suppress heel and toe wear to improve rigidity. It was also found that the smaller the ratio of the cross-sectional groove depth ratios, the more the heel-and-toe wear was suppressed. Further, it has been found that the steering stability on the WET road surface is prevented from being lowered by making the width of the IN-side cross-sectional groove wider than the width of the OUT-side cross-sectional groove.

  In addition, compared with Example 3, Example 2 has a larger inclination angle of the cross-sectional groove formed on the OUT side than the case where the inclination angle of the cross-sectional groove formed on the IN side is the same. It was found that heel-and-toe wear is further suppressed when the inclination angle of the cross-sectional groove formed on the side is larger than the inclination angle of the cross-sectional groove formed on the IN side.

It is a figure which shows the surface of the tread which concerns on embodiment of this invention. It is a figure which shows the cross section of the tread which concerns on embodiment of this invention. It is a figure which shows the cross section of the cross-sectional groove | channel which concerns on embodiment of this invention. It is a figure which shows the surface of the tread which concerns on the prior art example 1 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire 12 ... Tread 14 ... Circumferential groove | channel 16 ... Cross-sectional groove | channel 18 ... Horizontally long block R ... Chamfering radius

Claims (4)

The tread is formed in at least two circumferential grooves extending in the tire circumferential direction, a central region and an end region defined by the circumferential grooves, and 3 ° with respect to the circumferential groove. A cross-sectional groove that intersects at an angle of 10 ° with respect to the cross-sectional groove and a horizontal block that is defined by the crossing of the circumferential groove and the cross-sectional groove, and the tread pattern is the center in the tire width direction. A pneumatic tire that is asymmetric in line,
The cross-sectional groove formed in the inner region inside the tire equator line when the vehicle is mounted is closed to the circumferential groove, and the cross-section formed in the outer region outside the tire equator line when the vehicle is mounted The groove opens to the circumferential groove, the width of the cross-sectional groove of the outer region is smaller than the width of the cross-sectional groove of the inner region, the negative rate of the inner region is 38% to 42%, A pneumatic tire characterized in that a negative rate in the outer region is 30% to 34%.   The chamfer radius at the edge of the circumferential cross section of the horizontally long block formed in the outer region is smaller than the chamfer radius at the edge of the circumferential cross section of the horizontally long block formed in the inner region. The pneumatic tire according to claim 1.   2. The pneumatic tire according to claim 1, wherein a ratio of a depth of the circumferential groove formed in the outer region to a depth of the cross-sectional groove is 1: 0.82 to 0.85. .   The air according to claim 1, wherein an inclination angle of a side surface of the cross-sectional groove formed in the outer region is larger than or equal to an inclination angle of a side surface of the cross-sectional groove of the inner region. Enter tire.

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