JP2006192929A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve driveability on snow of a pneumatic tire without increasing negative ratio and edge components of the whole of a tread pattern. <P>SOLUTION: In this tire 10, a tread of the tire 10 is provided with an asymmetric tread pattern for designating the outside and inside at the time of mounting the tire 10. The tread pattern is provided with a plurality of sipes 22 in a rib or a block 20. The negative ratio of a rib groove 12 of the pattern is larger at the mounting outside than that at the mounting inside, and the negative ratio of a lug groove 14 of the pattern is smaller at the mounting outside than that at the mounting inside. A block length of a shoulder part of the pattern is longer at the mounting outside than that at the mounting inside. The interval of the sipe 22 of the shoulder part of the pattern is longer at the mounting outside than that at the mounting inside. The edge components of the sipe 22 per unit in the shoulder part of the pattern at the mounting inside are more than those at the mounting outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that is used in a vehicle traveling on a snowy road and has improved on-snow handling stability.

  In general, a pneumatic tire is provided with a plurality of belt layers and a tread sequentially on the circumference of the crown portion of the toroidal radial carcass, and a tread portion is provided on the circumference of the crown portion in order to improve grip performance with a road surface. The tread portion forms a plurality of rib rows by forming a plurality of rib grooves (circumferential grooves) extending in the tire circumferential direction on the tread portion contacting the road surface, and further extends in the tire width direction on the rib rows. A large number of lug grooves (lateral grooves) are formed at appropriate intervals, and a block (land portion) is formed by these rib grooves and lug grooves.

By the way, conventionally, when running on a snowy road in a pneumatic tire for winter, there is a difficulty that the tire slips on the snow surface without gripping the snowy road. Therefore, in order to improve acceleration / braking performance at the start of snowy roads and snow handling stability, a design has been made to provide sipes on the tire tread pattern block. However, there is a problem that the handling stability on the paved road cannot be secured. Even on the snow, if the sipe edge is excessively increased, the block rigidity is lowered and the snow handling stability is deteriorated. Therefore, there is a limit to the method of simply increasing the sipe to improve the performance on snow.
In particular, when turning the vehicle, the ground pressure on the outside of the wheel when turning turns increases due to load movement, so if the sipe is increased, the block rigidity is insufficient. To cope with this, the sipe is reduced to reduce the block rigidity. If the tire height is increased, there is a problem that the tire cannot grip the snow surface and sufficient acceleration / braking cannot be obtained.

  However, there is no prior art that can directly solve this problem, but the similar one is that, in terms of the negative rate, the driving performance on ice and snow, which are contradictory to each other, is compatible. In order to achieve this, there has been known an improvement in the tread groove configuration of the tire and the arrangement of sipes provided in the land (Patent Document 1). However, this tire does not consider an increase in contact pressure due to load movement at the time of turning. Therefore, this tread pattern cannot solve the problem of the pneumatic tire for snow surface.

Also, when turning the tire, the outer tread part bears a greater force than the inner tread part, so there is a zigzag circumferential groove in the outer area of the tread, and this groove There is also known a pneumatic radial tire in which the edge effect in cornering on snowy roads is remarkably enhanced by increasing the total value of the groove edge length per pitch, and the snow performance including slip resistance is improved. (Patent Document 2).
However, this tire is intended to improve the handling stability performance and snow performance at the same time, including anti-hydroplaning performance. Again, it is important to improve the block rigidity against the increase in ground pressure by load movement during turning. No particular consideration is given, and therefore the above-described problem of the pneumatic tire for snow cannot be solved.

As another example, FIG. 4 shows an example of a conventionally used pneumatic tire for a snow surface, which is not described in the patent literature.
The tread pattern shape of the tire 10 is defined by four rib grooves (circumferential grooves) 12, a plurality of lug grooves (width direction grooves) 14 intersecting with the rib grooves 12, and the grooves 12, 14. And a plurality of sipes 22 formed in the block 20. The lug grooves 14 are disposed in the center block portion 20c so as to be inclined in the width direction of the tire and from there to the outside (Out) side or the inside (In) side of the tire. The plurality of sipes 22 formed in the partitioned block 20 are arranged substantially parallel to the lug grooves 14 respectively.

In this conventional winter tire, as shown in the drawing, the groove component in the width direction and the sipe arrangement are generally symmetrical. This is because it is designed on the premise that the inside and outside of the mounting are equal inputs, and no particular consideration is given to changes in the ground pressure distribution due to weight movement during turning, which has a large impact on snow handling stability. .
Therefore, with this winter tire, it is impossible to solve the contradictory problem of securing block rigidity corresponding to the increase in the contact pressure distribution and at the same time obtaining sufficient acceleration and braking on the snow surface. .
JP 2000-229505 A JP-A-5-229310

  The present invention has been made in order to solve the above-described conventional problems. The purpose of the present invention is to devise a tread pattern and a sipe arrangement, etc., and to pay attention to the characteristics of an asymmetric pattern that can specify the inner side and the outer side. Providing tires that improve on-snow performance, particularly on-snow handling stability, without increasing the overall pattern negative ratio (ratio of groove surface area to pattern surface area) and edge components by making the components and sipes appropriate. It is.

In order to achieve this object, the invention of claim 1 includes a plurality of rib grooves provided in a circumferential direction of a tire, a plurality of lug grooves provided in a tire width direction and intersecting the plurality of rib grooves, In a pneumatic tire having a tread pattern composed of ribs or blocks partitioned by rib grooves and lug grooves, the rib or block has a plurality of sipes, and the negative rate related to the rib grooves of the pattern is on the outer side of the mounting side The negative rate regarding the lug groove of the pattern is smaller on the outer side than the inner side, the shoulder block length of the pattern is larger on the outer side than the inner side, and the shoulder sipe interval of the pattern is The outer side of the mounting is larger than the inner side of the mounting.
According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the sipe edge component per unit width in the shoulder portion of the pattern is larger on the inner side than on the outer side.
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the sipe edge component per unit width in the center portion of the pattern is in the shoulder portion of the pattern on both the outer side and the inner side of the mounting. It is characterized by being larger than the sipe edge component per unit width.

  According to the present invention, the groove arrangement and the sipe arrangement of the asymmetric pattern are defined, the block outer rigidity is secured at the mounting outer shoulder portion with a high contact pressure, and the edge according to the sipe density and the lug groove component at the mounting inner shoulder portion with a low contact pressure. By ensuring the effect and the snow column shearing force, it is possible to ensure on-snow maneuvering stability especially during turning and to obtain good on-snow running performance.

  The present invention changes the characteristics of the pneumatic tire to the edge effect, snow column shear force, and block rigidity on the inner side and the outer side, respectively, with an asymmetric pattern that can specify the inner side and the outer side. In other words, block rigidity is secured at the outer shoulder part where the contact pressure is high, and edge effect and snow column shear force are secured by the sipe density and lug groove component at the inner shoulder part where the contact pressure is low. It is intended to ensure the handling stability on snow.

Next, one embodiment of a pneumatic tire of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view of a developed tread pattern shape of the pneumatic tire 10 of the present embodiment.
The tread pattern shape of the tire 10 is defined by four rib grooves 12, a plurality of lug grooves 14 that intersect the rib grooves, and the grooves 12, 14 as in the conventional pneumatic tire. Block 20 and sipe 22 formed in each block 20, and the lug groove 14 extends in the width direction of the tire 10 in the center block 20 c portion, and from there to the outside (Out) side or inside (In) side The plurality of sipes 22 formed in the block 20 defined by the grooves 12 and 14 are disposed substantially parallel to the lug grooves 14.

  Here, in the pneumatic tire 10 of the present embodiment, in the mounting outer shoulder block 20a in which the ground pressure distribution becomes high when turning, in order to ensure block rigidity, the interval between the sipes 22 is widened and the width of the lug groove 14 is narrowed. The lug groove component is lowered, and conversely, in the mounting side inner shoulder block 20b, the sipe is increased and the width of the lug groove 14 is increased and the groove width component is increased to increase the sipe and widen the lug groove ( Block length is reduced), and snow column shear force is secured while ensuring the edge effect. Also, by adopting such a tread pattern shape, the negative rate decreases at the outer portion of the mounting and the wet performance deteriorates as it is, so the rib groove 12 component is made larger than the inner side of the mounting to prevent this. ing.

FIG. 2A is a plan view for explaining a state in which a pneumatic tire provided with a tread pattern according to an embodiment of the present invention is mounted on a vehicle, and FIG. 2B is when the vehicle turns (left turn here) The direction of load movement at.
As shown in FIG. 2B, when the vehicle turns, as shown in FIG. 2A, the load of the tire (outer ring) 10 located on the outer side of the turn increases due to the load movement by the roll, and on the ground contact surface of the tire 10 by lateral input The contact pressure of the outer shoulder block 20a is increased. That is, in the outer shoulder block 20a (a part of which is enlarged by a circle Y in FIG. 2A), the contact pressure becomes large, so that the block rigidity in that region is increased to withstand this. On the other hand, in the mounting inner shoulder block 20b (a part thereof is enlarged by a circle X in FIG. 2A), the contact pressure is small, and in this part, the edge effect and the snow column are used for acceleration / braking on the snow surface. The sipe density is increased so that the shearing force is increased, and the width of the lug groove 14 is increased to increase the groove width component.
Since the shoulder portion contributes greatly to the snow handling stability when turning the vehicle, the snow handling stability can be maintained even when turning the vehicle by using the tread pattern shape as described above.

  For each component on the outer side and inner side, the negative rate on the outer side is preferably 105-140% compared to the inner side, and the rib groove component on the outer side is preferably 102-400% relative to the inner side. The lug groove component is preferably 25 to 95% of the inner side of the wearing, the shoulder block length on the outer side of the wearing is preferably 105 to 200% of the inner side of the wearing, and the shoulder sipe interval on the outer side of the wearing is 120 to 180% of the inner side of the wearing. Is desirable.

  Here, the generation mechanism of μ on the snow (traction / brake) is as shown in FIG. 3, the compression resistance Fa as the running resistance of the entire surface of the tire, the surface frictional force Fc of the block surface as the driving force, and the snow column shearing force at the groove. Fb and the edge effect of sipe edge / block edge. In the present invention, the block rigidity is secured on the outside of the mounting, and the edge effect by the sipe edge and the snow column shear force Fc by the lug groove 14 can be secured on the inside of the mounting. Without increasing the edge component and the negative rate of the entire pattern, block rigidity, edge effect, and snow column shear force can be effectively obtained particularly in the shoulder portion that is important for snow handling stability.

For each component on the outer side and inner side, the sipe edge component per unit width on the inner side is preferably 105 to 180% in comparison with the outer side of the mounting. By making the sipe edge component per unit width in the shoulder portion of the pattern significantly larger on the inner side than on the outer side, the edge effect on the inner side can be further enhanced.
In addition, if the sipe edge component per unit width in the center portion (or center block) of the pattern is larger than the sipe edge component per unit width in the shoulder portion of the pattern in both the outer side and the inner side, the load during turning The edge effect can be further enhanced in the center portion where it is difficult to change the contact pressure distribution due to movement, and stable snow traction / snow brake performance can be exhibited.

  In this case, it is desirable that the sipe edge component per unit width in the center portion is 102 to 200% with respect to the wearing inner shoulder portion and 107 to 350% with respect to the wearing outer shoulder portion.

Example The rim and the internal pressure are based on the applicable rim and air pressure-load capacity correspondence table defined in JATMA YEAR BOOK (2004, Japan Automobile Tire Association Standard), and the tire size of the tire manufactured as an example is 195 / 65R15. The groove depth of the block is 9 mm, the sipe depth is all 7.5 mm, and the pattern shape is the device outer shoulder and inner shoulder as shown in FIG. The rib groove distribution, lug groove distribution, shoulder block length, shoulder sipe interval, and shoulder edge component per unit width are made the same. On the other hand, as shown in FIG. The block length is larger than the shoulder, the sipe interval and rib groove width are increased, and the inner In Ruda portion was sipe density than the installation-outer side shoulder large, the setting of the wide width of the lug grooves in the large. Note that the overall negative rate is 35%, and the overall edge components are the same.

In the test, each of the above tires was assembled to a rim of 6J-15 at an internal pressure of 200 kPa, mounted on a passenger car, and a steering stability test on snow was performed. The snow maneuvering stability test was conducted using a feeling evaluation by a test driver.
The results are shown in Table 1. The result of feeling evaluation is expressed by an index of feeling score, and the index is good.

  As is apparent from Table 1, the on-snow handling stability is 117 when the conventional product is set to 100, and the on-snow running performance is clearly improved.

It is a development top view showing the tread pattern of the pneumatic tire of the present invention. It is a top view for demonstrating arrangement | positioning structure when the pneumatic tire of this invention is mounted | worn with the vehicle. FIG. 3 is a side view schematically showing a part of a tire for explaining a mechanism for generating traction and braking on snow. It is an expansion | deployment top view which shows the tread pattern of the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... Rib groove, 14 ... Lug groove, 20 ... Block, 22 ... Sipe.

Claims (3)

A plurality of rib grooves provided in the circumferential direction of the tire, a plurality of lug grooves provided in the tire width direction and intersecting with the plurality of rib grooves, and ribs or blocks defined by the rib grooves and the lug grooves. In pneumatic tires with tread pattern,
The rib or block has a plurality of sipes, and the negative rate related to the rib groove of the pattern is larger on the outer side than on the inner side,
The negative rate related to the lug groove of the pattern is smaller on the outer side than the inner side, the shoulder block length of the pattern is larger on the outer side than the inner side, and the shoulder sipe interval of the pattern is the inner side on the outer side Pneumatic tire characterized by being larger. In the pneumatic tire according to claim 1,
The pneumatic tire according to claim 1, wherein the sipe edge component per unit width in the shoulder portion of the pattern is larger on the inner side than on the outer side. In the pneumatic tire according to claim 1 or 2,
The pneumatic tire according to claim 1, wherein a sipe edge component per unit width in the center portion of the pattern is larger than both a sipe edge component per unit width on the outer side and inner side of the shoulder portion of the pattern.

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