JPH08104112A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To restrain the break-off of a block in a tire for heavy load, restrain the worsening of steering stability in a tire for passenger car, and improve the performance on ice without lowering the wet performance, by increasing siping density, and restraining fall of block rigidity. CONSTITUTION: This pneumatic tire is provided with block land parts 4a, 4b partitioned by a plurality of longitudinal grooves 2 extending around a tread part 1, and many lateral grooves 3 squarely crossing with the longitudinal grooves 2 on a tread part 1 and respective two lateral sipes 5a, 5b are arranged on the block land parts 4a, 4b. Accompanying arrangement of the lateral sipes 5b, 5c adjacent to the lateral grooves 3, the end part in the width direction of lower land part rigidity in block land pars 14 actually partitioned by these lateral sipes 5b, 5c are strengthened by providing groove bottom rising parts 6 and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a block land portion, which is divided into a plurality of vertical grooves extending around a tread portion, and a plurality of lateral grooves intersecting the vertical grooves, in the tread portion. The present invention relates to a pneumatic tire in which a plurality of lateral sipes are arranged in a block land portion and which is excellent in running performance on a snowy and snowy road surface.

[0002]

2. Description of the Related Art With the prohibition of use of spiked tires, various improvements in treads have been made in search of better studless tires. In order to increase the edge component of the studless tire and improve the performance on ice, the tread part is formed in a block pattern,
It is useful to arrange a large number of sipes on the land portion of the block.

However, for example, when a large number of open sipes extending in the width direction of the block land portion and opening with two vertical grooves are provided, the edge component increases, but the block land portion is divided by the open sipes. Therefore, the rigidity of the entire block land portion is reduced. As a result, sufficient performance on ice cannot be obtained. In particular, disposing the open sipe adjacent to the lateral groove greatly reduces the land rigidity of the block land portion divided by the open sipe.・ The deformation during driving becomes large and the block is liable to be broken.In the case of tires for passenger cars, the collapse of the block reduces the actual ground contact area and deteriorates the steering stability. There was a risk that the steering stability would also deteriorate. Therefore, in order to improve the on-ice performance and the like, it is necessary to provide a means capable of ensuring the rigidity of the land portion of the block even if the disposition density of sipes is increased.

As a means for this purpose, the lateral sipe adjacent to the lateral groove is opened in only one longitudinal groove and terminated in the block land portion, as in the pneumatic tire described in Japanese Patent Laid-Open No. 2-200503. It is useful to use a plurality of one-end open sipes or an open sipes in which one end has a cut depth smaller than that of the other end.

[0005]

However, the inventors have found that
When the rigidity of the block land portion of these tires was locally investigated, in the former case, the block land portion is divided by the one end opening sipe on the side where the one end opening sipe opens with the longitudinal groove. The rigidity will be lower than that of the land portion at the position, and in the latter case, the rigidity of the block land portion on the side with the deeper cutting depth will be lower than that at the other position. Therefore, it has been found that the land portion where the rigidity of the land portion is reduced is largely deformed similarly to the land portion where the normal open sipe having a constant cutting depth is arranged. Therefore, even in these cases, sufficient rigidity of the land portion cannot be obtained in the land portion that is largely deformed, and the above-mentioned problems cannot be said to be solved.

In view of the above, the present invention provides a pneumatic tire having a large number of lateral sipes provided in a block land portion, and particularly, the arrangement shape of the lateral sipes adjacent to the lateral groove is appropriate in which the rigidity of the block land portion is remarkably reduced. In addition, the sipe density is increased by increasing the sipe density by reinforcing the block land part where the rigidity of the land partly decreases due to the disposition of this lateral sipe with the strengthening means. It suppresses the decrease in block rigidity due to the increase of the tire load, blocks the block in heavy-duty tires, and deteriorates the steering stability in passenger car tires, and improves the on-ice performance without reducing the wet performance. The purpose is to plan.

[0007]

In order to achieve the above object, the pneumatic tire of the present invention comprises a plurality of vertical grooves extending around the tread portion and a plurality of lateral grooves intersecting these vertical grooves. The tread portion has a block land portion divided by, and a plurality of horizontal sipes are arranged in the block land portion. With the arrangement of the horizontal sipes adjacent to the lateral groove, the lateral sipes are substantially divided. The pneumatic tire is characterized by having reinforcing means for correcting a difference in rigidity of a land portion which occurs at both widthwise ends of the block land portion thus formed.

Specifically, the lateral sipe adjacent to the lateral groove is
One end should be open to the vertical groove or horizontal groove, and the other end should be a one-end open sipe that terminates substantially in the block land, or both ends should be open to the vertical groove or horizontal groove, and this one end should be sipe cut compared to the other end. It is preferably an open sipe with a shallow depth, and as the reinforcing means, a groove bottom ridge is provided in the lateral groove portion facing the widthwise end of the block land portion where the rigidity of the land portion is smaller. That is, at the widthwise end of the block land portion where the rigidity of the land portion is smaller, the angle formed by the groove wall portion of the lateral groove facing the block land portion and the tread surface of the block is the other widthwise end. An angle between the groove wall portion of the vertical groove facing the block land portion and the block land tread at the widthwise end of the block land portion where the land rigidity is smaller. Is larger than the other widthwise end When the groove wall portion of the lateral groove facing the widthwise end portion towards the land portion rigidity is small the block land portion, also protrude from the other groove wall portions, or it is preferably to combine these.

It should be noted that the vertical groove does not necessarily have to be parallel to the equatorial plane of the tire, and the horizontal groove does not necessarily have to intersect with the vertical groove at an angle orthogonal to the vertical groove.
In short, in the present invention, the sipes may be arranged so as to intersect the tire rotation direction and the counter rotation direction at a relatively large angle. Also, the block land portion that is "substantially" divided by the horizontal sipe adjacent to the horizontal groove,
This is because, in addition to the case where the lateral sipe is an open sipe, it is assumed that the lateral sipe is a one-end open sipe, that is, when the lateral sipe is a one-end open sipe, the lateral sipe is extended at the end of the one-end open sipe. This is because it is assumed that the open sipe has been made, and the block land portion is divided by this open sipe. Further, one end of the one-end open sipe is opened to the vertical groove or the horizontal groove and the other end is “substantially” terminated in the block land portion in the case of the open sipe where the horizontal sipe has a partially reduced sipe depth. This is to include the case where it changes into an open sipe after the initial wear. When the lateral sipe is an open sipe at one end, its length is 50% of the length of the open sipe.
It is preferable to exceed it.

FIG. 1A shows a typical tread pattern of a pneumatic tire according to the present invention, and FIG. 2A shows an enlarged view of two block land portions of this tire. 1 in the figure
Is a tread portion, 2 is a vertical groove, 3 is a lateral groove, 4 is a block land portion, 5 is a lateral sipe adjacent to the lateral groove, 6 is a groove bottom ridge, 7
Is an opening of the lateral sipe 5, and 8 is an equatorial plane of the tire. This pneumatic tire is composed of four vertical grooves 2 extending in a straight line parallel to the tire equatorial plane 8 and a large number of lateral grooves 3 orthogonal to the equatorial plane 8 and intersecting the vertical grooves 2. Two straight lateral sipes 5 are placed in the divided rectangular block land portion 4a.
It has a and 5b. In this figure, horizontal sipes 5a, 5
Although b is a one-sided open sipe arranged alternately, it is not limited to this and may be, for example, an open sipe with an appropriate cut shape. The shape of this open sipe will be described later.

Block land portions 4a sandwiching the lateral groove 3a,
4b, one end opening sipe 5b, 5 adjacent to the lateral groove 3a
Block land portion 14 substantially separated by c (FIG.
(Indicated by a diagonally downward-sloping portion in (a)), the width-direction end portion 1 located on the side of the openings 7b, 7c of the one-end opening sipes 5b, 5c.
2b, 12c (indicated by hatching in the lower right of FIG. 2 (a))
In order to reinforce the groove width, a groove bottom ridge 6a (indicated by a diagonal line rising to the right) is provided in the portion of the lateral groove 3a facing the width direction end portions 12b and 12c. The height of this groove bottom raised portion 6,
The length and the width are 0.25 to 0.75 times the depth of the lateral groove 3, the groove width, and the width of the block land portion 4, respectively.
The range of 0.5 to 1.0 times and 0.2 to 0.5 times is preferable. FIG. 1B shows a typical sectional shape of the groove bottom protrusion 6. Further, when it is necessary to suppress the deterioration of the wet performance when the tire is worn to some extent, the same figure (c)
A cut sipe 17 can be provided between the groove bottom raised portion 6 and the lateral groove 3 as described above, or in the groove bottom of the groove bottom raised portion 6 as shown in FIG. Since the cut sipe 17 is closed by crushing, the reinforcing effect is hardly reduced, and when the tire is worn to some extent, it appears on the tread surface and can contribute to improvement of wet performance.

Another embodiment in which the widthwise end portions 12b and 12c are strengthened by disposing the groove bottom raised portion 6a in the lateral groove 3a is, for example, as shown in FIGS. 2 (b) to 2 (e). ,
In each case, the groove bottom ridge 6a is formed into a rectangular block land portion 4a,
2b is provided on the side of the vertical groove 2a where the horizontal sipes 5b and 5c respectively arranged in 4b are opened.
(F) shows two one-end opening sipes 5 adjacent to the lateral groove 3a.
a, 5b and 5c, 5d facing the respective block land portions 4b, 4a respectively, and the groove bottom raised portion 6a is arranged at the portion of the lateral groove 3a facing the width direction end portions 12b, 12c having the smaller block rigidity. 3 (a) and 3 (b), the block land portion 4 has a parallelogram shape,
This is an example in which the one-end opening sipe 5 is provided substantially in parallel to the lateral groove 3a, and the former forms the one-end opening sipe 5 in a straight line shape and the latter is formed in a wavy shape. Further, FIG. 4A shows the groove wall 9 of the lateral groove 3 and the one-end opening sipe 5 in a polygonal line shape,
Further, instead of the groove bottom raised portion 6, the width direction end portion may be strengthened by making the sipe depth on the opening side of the one end opening sipe 5 shallow. FIG. 5 (a) shows the arrangement angle α1 and α2 in the depth direction of the groove wall 9 of the lateral groove 3 and the one-end opening sipe 5 being acute angles as shown in FIGS. 5 (b) and 5 (c), respectively. 6, the block land portion 4 has a special shape, and one end opening sipes 5a, 5b adjacent to the lateral groove 3a are formed in the lateral groove 3a.
It is arranged such that it is opened at a.

The groove bottom ridges 6 described so far are all provided over the groove width W of the lateral groove 3, but FIG.
As shown in (a) and (b), the groove bottom protrusion 6 has the groove width W.
May be provided only in a part of. The groove bottom protrusion 6
When it is provided in the entire vertical groove 2 or a part thereof, or in the entire horizontal groove 3, the drainage property may be deteriorated, and a part of the horizontal groove 3 extends over the groove width W. When it is provided at a location, the portion of the lateral groove 3 sandwiched by these groove bottom raised portions 6 becomes a so-called bag groove, and pattern noise due to an air pumping phenomenon may occur at the time of tire grounding. This pattern noise tends to become more prominent as the wear of the tread portion 1 progresses.
Therefore, when reinforcing the width direction end portion 12 having a smaller land rigidity by disposing the groove bottom ridge portion 6, the groove bottom ridge portion 6 is provided on the lateral groove 3 facing the width direction end portion 12. It is preferable to provide only one place in the part.

As another embodiment, as shown in FIG. 8, an angle β1 formed by the groove wall portions 9a and 9c of the lateral groove 3a facing the widthwise end portions 12a and 12b and the block land portion tread 10 is an obtuse angle. Or, as shown in FIG. 9, the angle γ1 formed between the groove wall portions 11a and 11c of the vertical groove 2 facing the width direction end portions 12a and 12b and the block land portion tread 10 is an obtuse angle. By doing so, it is preferable to strengthen the width direction end portions 12a and 12b in which the block rigidity is largely reduced.

Further, as shown in FIG. 10, the end portion 1 in the width direction is formed.
Groove wall portions 9a and 9 of the lateral groove 3a facing 2a and 12b
The width-direction end portions 12a and 12b having a large decrease in block rigidity can also be strengthened by projecting c from the other groove wall portions 9b and 9d by the length L. In addition,
FIG. 10 shows the case where the projected groove wall portion 9a and the groove wall portion 9c are displaced from each other.
A part of a and 9c may face each other and may be adjacently arranged (FIG. 11A). This typical cross-sectional shape is shown in FIG.
It shows in (b). This cross-sectional shape has groove wall portions 9a and 9c.
Only the upper portions 18a and 18c of both of the above are projected, and the gap formed by these protruding portions is made into a sipes. As another specific example, as shown in FIG. 11C, central portions 19a and 19 of both groove wall portions 9a and 9c are formed.
In the case where only c is projected and the gap formed by these projecting portions is set to about sipes, or as shown in FIG. 11D, only the central portion 19c of the groove wall portion 9c is projected to the vicinity of the groove wall portion 9a. However, various cross-sectional shapes are possible.

In all of the embodiments described so far, the lateral sipes 5a, 5b are one-sided open sipes, but as other embodiments, the lateral sipes 5a, 5b.
b may be an open sipe as shown in FIG. However, in this case, as shown in FIGS. 13B to 13J, the open sipes 5a and 5b are provided on the side of the other width direction ends 15a and 15b, respectively.
A means for arranging so that the depth of cut is shallower than that of a and 12b, and strengthening the lowered land rigidity on the side in the width direction ends 12a, 12b (for example, shown in FIG. 13 (a)). By providing such a groove bottom raised portion 6), there is substantially the same action as in the case of the one-end opening sipe described above.

The above description shows only a part of the embodiments of the present invention, and these inventions can be variously combined and changed within the scope of claims.

[0018]

The tire of the present invention is provided with a lateral sipe adjacent to the lateral groove (specifically, an open sipe having an opening sipe at one end or an open sipe with different sipe cut depths at both ends). Having a strengthening means for correcting the difference in land rigidity that occurs at both widthwise ends of the substantially divided block land portion, for example, the widthwise end 12b of the block land portion where the land rigidity is smaller. , 12c are provided with groove bottom ridges 6 (FIG. 2 (a)), and the groove wall portions 9a and 9c of the lateral groove 3a facing the width direction end portions 12a, 12b and the blocks. Angle β1 with land tread 10
Is the groove wall portion 9b of the lateral groove 3a facing the other end in the width direction.
And 9d and the land tread 10 of the block are made larger than the angle β2 (FIG. 8), and the width direction end portions 12a, 12b.
An angle γ1 formed by the groove wall portions 11a and 11c of the vertical groove 2 facing the groove and the block land tread 10 is defined by the groove wall portions 11b and 11d of the vertical groove 2 facing the other end in the width direction and the block land tread. It is made larger than the angle γ2 formed by 10 (FIG. 9), or the groove wall portions 9a, 9c of the lateral groove 3a facing the width direction end portions 12a, 12b are made to protrude more than the other groove wall portions 9b, 9d. As a result (FIG. 10), even if the sipe density is increased as compared with the conventional tire, it is possible to suppress the entire and local deformation of the block land portion 4.

Further, since the tire of the present invention has a high sipe density and partially efficiently reinforces the width direction end portion 12 in which the rigidity of the land portion is lowered due to the disposition of the sipe, the tire of the present invention is drainable. The required groove volume of the vertical groove 2 and the horizontal groove 3 can be secured. In addition, the decrease in the rigidity of the land portion when the lateral sipe is arranged in the block land portion is remarkable when the lateral sipe is provided adjacent to the lateral groove, and the lateral sipe other than the lateral sipe adjacent to the lateral groove 3 is provided. Regarding (when three or more horizontal sipes are provided in the block land portion 4), since the local decrease in the rigidity of the land portion due to this arrangement is small, a normal open sipe with a constant cutting depth is used. It can be changed appropriately. Furthermore, when it is desired to further improve the block chip resistance in a heavy-duty tire, the one-end opening sipe 5 is a flask sipe whose land inner end 16 is spherical, as shown in FIG. 7B. Is preferred.

[0020]

EXAMPLES Specific examples of the pneumatic tire according to the present invention will be described with reference to the drawings. The invention tire 1 used in Example 1 has the tread portion 1 having the block pattern shown in FIG. 1A, and four longitudinal grooves 2 extending in parallel and linearly with the equatorial plane 8 of the tire, The tread portion 1 is provided with a rectangular block land portion 4 which is orthogonal to the equatorial plane 8 and is divided by a plurality of lateral grooves 3 which intersect the vertical groove 2.
As shown in FIG. 2A, the vertical groove 2 is formed in the block land portion 4a.
Two straight one-end open sipes 5a, 5b, which open in a and 2b and terminate in the block land portion 4a, are provided alternately. In addition, the block land portion 4a sandwiching the lateral groove 3a,
4b, the groove bottom ridge is formed in the portion of the lateral groove 3a facing the width direction end portions 12b, 12c of the block land portion portion 14 which is substantially divided by the one-end opening sipes 5b, 5c, respectively, which has a smaller land portion rigidity. 6a is provided. The block land portion 4 has a length of 23 mm and a block width of 30 mm.
Has a groove depth of 20 mm and a groove width of 10 mm,
The lateral groove 3 has a groove depth other than the groove bottom protrusion 6 of 15 mm,
The groove bottom protrusion 6 has a groove depth of 8 mm, a length of 10 mm, and a width of 7 mm, which is the same as the lateral groove 3, at that position. Further, the one-end opening sipe 5 has a depth of 10 mm, a width of 0.5 mm, and a length of 24 mm. Inventive tires 1 to 5 and comparative tires 1 and 2 are all heavy-duty pneumatic tires and have tire sizes of 11
R22.5.

In the inventive tire 2 used in Example 2, the tread portion has the block land portion 4 shown in FIG. 6, and the four longitudinal grooves 2 extending in a straight line parallel to the equatorial plane 8 of the tire.
The tread portion 1 is provided with a block land portion 4 divided by the vertical groove 2 and a plurality of lateral grooves 3 extending in a stepwise manner. Each of the block land portions 4a was provided with three linear one end opening sipes 5b, 5c, 5d alternately.
The groove bottom raised portion 6a is provided with an opening 7 of the sipe 5a, 5b which is open at one end.
It was provided in the portion of the lateral groove 3a corresponding to a and 7b. The groove bottom ridge 6 has a groove depth of 8 mm and a length of 10 m at that position.
m, and its width was the same as that of the lateral groove 3. Block land 4
The length was 30 mm at maximum and 10 mm at minimum, and the block width was 30 mm at maximum and 15 mm at minimum. The vertical groove 2 has a groove depth of 20 mm and a groove width of 10 mm, the horizontal groove 3 has a groove depth other than the groove bottom raised portion 6 of 15 mm, and the one-end opening sipe 5 has a depth of 10 mm. The width was 0.5 mm, the length was 12 mm for the one-end opening sipe 5b, 5d adjacent to the lateral grooves 3a, 3b, and 24 mm for the other one-end opening sipe 5c.

The invention tire 3 used in Example 3 has the tread portion having the block arrangement shown in FIG. The openings 7a, 7b of the one-end opening sipes 5a, 5b adjacent to the lateral groove 3a are arranged in different vertical grooves 2a, 2b, respectively, and the end portion 1 in the width direction is formed.
The angle β1 formed by the groove wall portions 9a and 9c of the lateral groove 3a facing the 2a and 12b and the block land tread 10 is 110 °,
The same structure as the tire used in Example 1 except that the angle β2 formed by the other groove wall portions 9b and 9d of the lateral groove 3a and the block landing surface 10 is 90 ° and that the groove bottom ridge is not formed. Have.

Inventive tire 4 used in Example 4 has a tread portion having a block arrangement shown in FIG. The angle γ1 formed between the groove wall portions 11a and 11c of the vertical groove 2 which the one-end opening sipe 5 opens and the block land portion tread 10 is set to 110 °, and the other groove wall portions 11b and 11d and the block land portion tread 10 are formed. The tire has the same structure as the tire used in Example 3 except that the angle γ2 is 90 ° and the angles β1 and β2 are both 90 °.

Inventive tire 5 used in Example 5 has a tread portion having a block arrangement shown in FIG. Groove wall portions 9a, 9 of the lateral groove 3a facing the width direction end portions 12a, 12b.
The tire has the same structure as that of the tire used in Example 3 except that the length c of the c is projected from the other groove wall portions 9b and 9d by 2 mm and the angles β1 and β2 are both 90 °.

In the inventive tire 6 used in Example 6, the tread portion 1 has a block pattern shown in FIG. 14 (block land portions 4a and 4b forming this block pattern).
FIG. 15 is an enlarged view of FIG. ), Tire equatorial plane 8
4 longitudinal grooves 2 extending in parallel and linearly with respect to each other, and a large number of transverse grooves 3 orthogonal to the equatorial plane 8 and intersecting the longitudinal grooves 2.
A rectangular block land portion 4 divided by and was provided on the tread portion 1. In the block land portion 4b, two linear one-end opening sipes 5a, 5b which respectively open in the vertical grooves 2a, 2b and terminate in the block land portion 4b are alternately provided, and the lateral groove 3a is provided.
In the block land portions 4a and 4b sandwiching the two, the width direction end portions 12c and 12 of the block land portion portion 14 which are substantially divided by the one-end opening sipes 5c and 5a, respectively, have smaller land portion rigidity.
A groove bottom ridge 6a (hatched portion in the figure) is provided in the portion of the lateral groove 3a facing a, and the cut depth is constant in the block land portion sandwiched by the one-end opening sipes 5a, 5b.
A book of open sipes 13 was placed. Block land 4
Has a length of 20 mm and a block width of 20 mm, and the vertical groove 2 has a groove depth of 10 mm and a groove width of 7 m.
The lateral groove 3 has a groove depth of 10 mm, the groove width thereof is 5 mm, and the groove bottom ridge 6 has a groove depth of 5 m at that position.
m, its length was 7 mm, and its width was 5 mm, which is the same as that of the lateral groove 3. Further, both the one-end open sipe and the open sipe had a depth of 7 mm and a width of 0.5 mm, and the one-end open sipe 5a, 5b had a length of 12 mm. The invention tire 6 and the comparative tires 3 to 4 are all passenger car tires and have a tire size of 185 / 70R1.
It was set to 3.

The comparative tire 1 used in Comparative Example 1 has a tread portion having a block land portion 4 shown in FIG. 12 (a), and the block land portion 4 is provided with one open sipe 13. No. 13 is a tire having a conventional block pattern having a depth of 7 mm and a width of 0.5 mm.

In the comparative tire 2 used in Comparative Example 2, the tread portion has the block land portion 4 shown in FIG. 12 (b), and the block land portion 4 has two linear shapes instead of the open sipe. The tire has substantially the same structure as the tire used in Comparative Example 1 except that the one-end opening sipes 5a and 5b are alternately provided.

The comparative tire 3 used in Comparative Example 3 has a tread portion having a block land portion 4 shown in FIG. 16 (a), and the block land portion 4 has three open sipes with a constant cutting depth. 13 with these open sipes 13
Is a tire having a conventional block pattern having a depth of 7 mm and a width of 0.5 mm.

A comparative tire 4 used in Comparative Example 4 has a tread portion having a block land portion 4 shown in FIG. 16 (b), and the block land portion 4 has four open sipes with a constant cutting depth. The tire has substantially the same structure as that of the tire used in Comparative Example 3 except that No. 13 is included.

The above-mentioned test tires are divided into heavy-duty tires (invention tires 1 to 5 and comparative tires 1 to 2) and passenger car tires (invention tire 6 and comparative tires 3 to 4), respectively, on an ice brake. The performance and wet performance were evaluated. In addition, the former evaluated the block missing, and the latter evaluated the steering stability on the dry road surface.

In the on-ice braking performance test, tires are mounted on a vehicle, sudden braking is applied while running at a speed of 20 km / h, and the braking distance from the point where the braking is applied to the point where the braking is stopped is measured. The braking performance on ice was evaluated from the index value of. In the wet performance test, a tire worn by 50% was mounted on a vehicle, the tire was run on a wet road surface, and the driver evaluated the feeling. In the block chipping test (executed only for heavy-duty tires), after running an actual vehicle for 20,000 km, the presence or absence of block chips in the tire was examined and evaluated. Steering stability on dry roads (carrying out passenger car tires only) is as follows:
The driver evaluated the feeling.

These test results are shown in Table 1 and Table 2, respectively.
Shown in The values in Table 1 are 100 for the comparative tire 1.
And the numerical values in Table 2 are shown with the comparative tire 3 being 100, and the larger the numerical value, the better.

[0033]

[Table 1]

[0034]

[Table 2]

From the results of Table 1, invention tire 1 for heavy load
Nos. 5 to 5 are superior to the comparative tires 1 and 2 in terms of braking performance on ice. Regarding the wet performance, each of the invention tires 1 to 5 has the same level of performance as the comparative tire 1. In addition, although the tires worn by 50% were mounted on a vehicle and the passing noise during running was also measured, the invention tires 1 to 5 which do not form a bag groove
All of the tires had almost the same level as the comparative tires 1 and 2.

Further, from the results of Table 2, the invention tire 6 for passenger cars has the same braking performance on ice as the comparison tire 3
And 4 are superior. Regarding the wet performance, the inventive tire 6 has the same level of performance as the comparative tire 3.

[0037]

As compared with the conventional tire, the tire of the present invention can suppress the entire and local deformation of the block land portion even if the sipe density is increased. Further, since the tire of the present invention has a high sipe density and partially efficiently reinforces the widthwise end portion 12, it is possible to secure the groove volumes of the vertical groove 2 and the horizontal groove 3 necessary for drainage. it can. In particular, in the case of heavy-duty tires, block breakage due to braking / driving can be suppressed, and in the case of passenger car tires, steering stability can be ensured. In addition, in the tire of the present invention, since the sipe density is increased and the widthwise end portion 12 is strengthened partially efficiently, good drainage can be ensured.

[Brief description of drawings]

FIG. 1 (a) is a diagram showing a typical tread pattern of a pneumatic tire according to the present invention, and FIG. 1 (b) is
It is a figure which shows the typical cross-sectional shape when cutting the block land part shown to (a) by the HH line, (c) and (d).
[Fig. 6] is a diagram showing a specific example of another cross-sectional shape.

FIG. 2A is a plan view in which a part of a tread portion of the tire shown in FIG. 1A is extracted and enlarged, and FIGS.
(F) is a plan view showing a part of another tread portion according to the present invention.

3 (a) and 3 (b) are plan views showing a part of another tread portion according to the present invention.

FIG. 4 (a) is a plan view showing a part of another tread portion according to the present invention, and FIG. 4 (b) is a block land portion shown in (a) taken along line XX. FIG. 7C is a cross-sectional view of the block land portion shown in FIG. 9A taken along line YY.

FIG. 5 (a) is a plan view showing a part of another tread portion according to the present invention, and FIG. 5 (b) is a sectional view of the block land portion shown in (a) taken along line Z1-Z1. FIG. 6C is a cross-sectional view of the block land portion shown in FIG.
It is sectional drawing when it cut | disconnects by the Z2 line.

FIG. 6 is a plan view in which a part of another tread portion according to the present invention is extracted.

FIG. 7 (a) is a diagram in the case where a groove bottom protrusion is provided in a part of the groove width, and FIG. 7 (b) is a diagram in the case where the one-end opening sipe of (a) is a flask sipe. , (C) is (b)
It is sectional drawing when it cut | disconnects by the CC line.

FIG. 8 is a plan view in which a part of another tread portion according to the present invention is extracted, and a cross-sectional view taken along the line AA and the line BB.

FIG. 9 is a plan view in which a part of another tread portion according to the present invention is extracted, and a cross-sectional view taken along line D-D and line E-E.

FIG. 10 is a plan view in which a part of another tread portion according to the present invention is extracted.

FIG. 11 (a) is a plan view showing a part of another tread portion according to the present invention, and FIG. 11 (b) is a block land portion shown in FIG. 11 (a) cut along line JJ. FIG. 4C is a cross-sectional view of FIG. 4C, and FIGS. 7C and 7D are diagrams showing specific examples of other cross-sectional shapes.

12 (a) is a plan view showing a part of a tread portion of a comparative tire used in Comparative Example 1, and FIG.
4 is a plan view showing a part of a tread portion of a comparative tire used in Comparative Example 2. FIG.

FIG. 13 (a) is a plan view of a horizontal land sipe adjacent to the horizontal groove, in which two open sipes having different cutting depths at both ends in the width direction of the block land portion are arranged. (B)-(j) is the figure which showed the Example of various depth shape of the open sipe when it cut | disconnects on the FF line of (a), (k) is G of (a). It is the figure which showed the Example when it cut | disconnects on the -G line.

FIG. 14 is a diagram showing a part of a tread pattern of an inventive tire 6 used in Example 6;

FIG. 15 is an enlarged view in which one block land portion is extracted from the block pattern shown in FIG.

FIG. 16 (a) is an enlarged view of one block land portion extracted from the block pattern of the comparative tire 3,
(B) is an enlarged view in which one block land portion is extracted from the block pattern of the comparative tire 4.

[Explanation of symbols]

 1 Tread portion 2 Vertical groove 3 Horizontal groove 4 Block land portion 5 Horizontal sipe adjacent to the horizontal groove 6 Groove bottom ridge 7 Side sipe 5 opening 8 Tire equatorial plane 9 Horizontal groove groove wall 9a, 9c Groove wall portion 9b, 9d Other Groove wall portion 10 Block land tread 11 Vertical groove groove wall 11a, 11c Groove wall portion 11b, 11d Other groove wall portion 12, 12a, 12b, 12c End in width direction of land portion 13 Open sipe 14 Block land part 15a, 15b which is substantially divided by lateral sipe 5 Width end of the larger land part 16 Flask part 17 Flange part 17 Cut sipe 18 Upper part of groove wall 9 of lateral groove 19 Groove wall 9 of lateral groove Central part

Claims (7)

[Claims] 1. A tread portion has a block land portion divided by a plurality of vertical grooves extending around a tread portion and a plurality of lateral grooves intersecting with the vertical groove, and the block land portion has a plurality of block land portions. In a pneumatic tire with a horizontal sipe, the rigidity of the land portion that occurs at both widthwise ends of the block land portion that is substantially divided by the horizontal sipe adjacent to the lateral groove. A pneumatic tire having reinforcing means for correcting the difference between 2. The pneumatic tire according to claim 1, wherein the lateral sipe adjacent to the lateral groove is a one-end open sipe which has one end opening to the longitudinal groove or the lateral groove and the other end substantially terminating in the block land portion. 3. The air according to claim 1, wherein the lateral sipe adjacent to the lateral groove is an open sipe whose both ends are open to the longitudinal groove or the lateral groove and whose one end has a smaller sipe depth of cut than the other end. Included tires. 4. The reinforcing means, wherein a groove bottom ridge is provided in a lateral groove portion facing the widthwise end of the block land portion where the land portion rigidity is smaller. Pneumatic tire. 5. As a reinforcing means, an angle formed between a groove wall portion of a lateral groove facing the block land portion and a block land tread at a widthwise end of the block land portion where the rigidity of the land portion is small. The pneumatic tire according to claim 1, 2 or 3, wherein the width is larger than the widthwise end of the other side. 6. The reinforcing means comprises a groove wall portion of a vertical groove facing the block land portion and a block land tread at the widthwise end of the block land portion where the land rigidity is smaller. The pneumatic tire according to claim 1, 2 or 3, wherein the corner is made larger than the other end in the width direction. 7. The strengthening means according to claim 1, wherein the groove wall portion of the lateral groove facing the widthwise end portion of the block land portion portion, which has a smaller land rigidity, is projected more than the other groove wall portions. 2,
Or the pneumatic tire according to item 3.