JPH07228106A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce rolling resistance by providing a land part which is partitioned by multiple grooves at a cylindrical tread part which extends over a pair of right and left side walls in a pneumatic tire, and providing a sipe at a part which is swerved toward the outside in a lateral direction from the ground-contact width position of the land part which is located at the shoulder of the tread part. CONSTITUTION:Right and left side walls 2 and a cylindrical tread part 3 which extends over both the side walls form such a shape as stretches in a toroid shape around an equator surface O. The tread part 3 is provided with multiple grooves 4 in a peripheral direction, with two grooves on either side, at regular intervals, and partitions independent blocks 6 with a lug groove 5 which extends across the grooves. The respective blocks 6 in a shoulder block row 72 are provided with a sipe 11 in the proximity of a padless 10 on the outside in an axial direction from the ground-contact end E of the tread part. During running, shear distortion in peripheral and axial directions which is generated on the outside in the axial direction from the ground-contact end of the shoulder block is relieved by the sipe in a ground-contact area, thereby reducing rolling resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having reduced rolling resistance, and more particularly to a tire for passenger cars.

[0002]

2. Description of the Related Art The rolling resistance of a tire affects the fuel consumption of a vehicle. With the increasing awareness of global environmental protection in recent years, it has become more necessary than ever to reduce the rolling resistance of a tire. . In order to reduce the rolling resistance of the tire, it is necessary to reduce the energy consumed by the stress / strain cycle associated with the rolling of the tire. It is known that the tread portion is the largest when comparing the energy consumption of each portion with the side portion extending to the side and the tread portion located across both side portions. Therefore, for the tread part, use rubber suitable for rolling resistance reduction within the range where other important characteristics such as wear resistance are not significantly impaired, or embed the above rubber in the base part of the tread that does not appear on the surface throughout the wear life. As a result, the rolling resistance has been reduced mainly from the viewpoint of rubber.

[0003]

According to a detailed investigation by the inventors of the behavior of the tire on the ground contact surface when the tire runs, when the tire rotates and enters the contact area, the shoulder block and the axial outside The buttress portion (the upper part of the side wall) following is subjected to elongation deformation that significantly extends in the circumferential direction and compression deformation including bending that pushes the shoulder block in the direction of the equatorial plane of the tire. If is a radial structure, close to these deformed parts,
The side end of the buried belt layer is located, and the side end of this belt layer is also deformed together. As a result, inside this portion, as shear deformation in the circumferential direction and the axial direction, the tire acts cyclically when viewed partially, and continuously when viewed as a whole, and the loss in this case causes rolling of the tire. It was found that the resistance was greatly affected. And, such shear strain is significantly reduced on the shoulder block of the tread by functionally separating the buttress portion connected to the shoulder block, and without changing the tread rubber as conventionally performed, the tire is It has been found that the rolling resistance can be effectively reduced.

An object of the present invention is to provide a tire having reduced rolling resistance based on the above findings.

[0005]

SUMMARY OF THE INVENTION The present invention provides a tire having a cylindrical tread portion extending over a pair of left and right side walls, and a land portion divided by a plurality of grooves,
The pneumatic tire is characterized in that a sipe is provided at a portion axially outside from a ground contact end position of a land portion located on a shoulder of a tread portion. Here, the ground contact end position is an arbitrary position within the range of 5 mm in and out of the axial direction with reference to the ground contact end position when the normal internal pressure is filled and the normal load is applied. The definition with such a width is considered to be that the internal pressure / load that deviates from the regular internal pressure / normal load of a certain size is applied depending on the type of vehicle to be applied (especially electric vehicles that have been attracting attention in recent years). Because it will be done.

[0006]

The tire according to the present invention has a tread shoulder.
By providing a sipe in the axially outer portion of each block in the row of blocks from the grounded end, the circumference generated by the axial extension deformation and the axial compression deformation generated from the shoulder block to the buttress portion at the time of ground contact when the tire travels The directional and axial shear strains can be effectively relaxed, thereby reducing the rolling resistance of the tire.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
4 is a partial cross-sectional view and a partial plan view of a tire showing the present invention. In the sectional view and the plan view shown in FIGS. 1 and 2,
Right half from the equatorial plane O and side wall 2 per tire
Although most of the inner side in the radial direction is omitted, the left and right sidewalls 2 centered on the equatorial plane O and the cylindrical tread portion 3 extending across both sidewalls are connected in a toroidal shape. It has a known shape. And tread part 3
Are provided with a plurality of circumferential grooves 4 on one side of the equatorial plane O in the illustrated example, at substantially equal intervals, and extend across these circumferential grooves 4 to extend substantially in the circumferential direction. The independent block 6 is divided by a large number of lug grooves 5 provided at equal intervals. In whereby example shown in FIGS. 1 and 2, center block row, shoulder - block row, middle block row _71,
7 ₂ and 7 ₃ are formed. FIG. 2 shows an example of a caramel block prototyped according to the present invention. In the implementation, a straight or curved lug groove which intersects the circumferential groove 4 with an appropriate inclination is used for the lug groove 5. It goes without saying that it will be done.

In FIG. 1, reference numeral 8 is both side walls.
2 is a carcass that extends between bead rings (not shown) embedded in the radially inner ends of the polyester and the laser.
Fiber cords such as Yeon and Nylon are approximately 9 with respect to the equatorial plane O
It consists of one or two sheets arranged at an angle of 0 °.
The belt layer 9 is arranged between the carcass 8 and the tread portion 3 to strengthen the area corresponding to the tread portion. The belt layer is made by stacking layers 9 ₁ and 9 _{2 in} which steel cords are inclined and arranged at an angle of 10 to 30 ° with respect to the equatorial plane so that the cords intersect in different directions, and further on top of that. the Naironko - an auxiliary layer 9 ₃ formed by a circumferential spiral winding of de. The effect of the present invention is enhanced in the tire in which the auxiliary layer is arranged in this manner. This is because the belt layer and the reinforcing layer are less likely to be stretched, so that the rolling resistance is further reduced.

In the present invention, the shoulder block row 7 ₂
Each block 6 has a sipe 11 in the vicinity of the buttress 10 axially outside from the grounding end E of the tread portion. FIG. 2 shows the first embodiment of the present invention, in which the plane F including the ground end E is shown.
Block starting from a position separated by a distance d from
A plurality of sideways sipes 11 ₁ of 0.8mm width on the 6 (three in the example of FIG. 2) the distance e, is located away f. Here, the ground contact end E is the ground contact end when the tire is assembled on the rim, the regular internal pressure is filled, and the regular load (JATMA standard) is applied to the flat plate. Distance d from the ground end of the lateral sipe
Is at least 1 mm for the purposes of the present invention,
A range of 1-5 mm is preferred. Next, the distance e from the sipes and the distance f from the block end are preferably in the range of 3 to 10 mm, depending on the depth of the sipes and the block length, and in the case of applying to blocks of passenger car tires, the range is 2 to
Three can be provided. For sipe depth g,
30-60% of the total thickness of the portion where the sipe is provided is preferable. The reason is that if it is less than 30%, the rolling resistance cannot be reduced sufficiently, while if it exceeds 60%, the durability of that portion is adversely affected. If the belt layer is present on the extension line of the sipe (Fig. 1), it is necessary to separate the bottom of the sipe by about 1 mm from the belt layer.

A second embodiment of the present invention is shown in FIG.
The feature of this embodiment is that the blocks of the shoulder-block sequence are
6 at a distance d from the face F of the ground contact end lies in providing the vertical sipe 11 ₂ extending parallel to the plane F. When one vertical sipe is provided as shown in FIG. 3, it is preferable to provide a width that is wider than that of the horizontal sipe (0.8 to 3 mm). It is also possible to provide a plurality of narrower vertical sipes parallel to each other.

A third embodiment of the present invention is shown in FIG.
The feature of this embodiment is that the lateral sipe 11 ₁ shown in FIGS.
A combination of vertical sipe 11 ₂ lies in providing a. The extension of both types of sipes in the depth direction is the same at the deepest portion, as indicated by the symbol g in FIG. The lateral sipe 11 ₁ and the vertical sipe coupling portion 12 can be provided independently of each other, for example, by making the lateral sipe shallow, or by arranging some distance between the sipe.

[0012]

[Effects] In order to confirm the effect of the tire of the present invention thus constituted, the size of 185 / 65R14 is used for the tires of Example 1 shown in FIG. 2, Example 2 shown in FIG. 3 and Example 3 shown in FIG. In addition, a comparative tire without a sipe was prototyped, and rolling resistance was measured and evaluated. In making a tire, the carcass was a ply consisting of a 1500d / 2 polyester cord radial array (90 °), and the belt layer was a 1 × 5 × 0.22 steel cord inclined at an angle of 20 °. A three-layer structure in which the arranged layers are cross-laminated and an auxiliary layer forming a 0 ° arrangement of 1260d / 2 nylon code is arranged thereon, and the tread of the caramel block (circumferential block length 24 mm) shown in FIG. Was commonly used.

Regarding the sipes applied to the tire of the embodiment, the sipes width is 0.8 mm, the distance d from the ground contact end is 3 mm,
The ratio of the sipe depth g to the total thickness was 54% and was applied in common. The ground contact end E was determined by mounting the tire on a rim of 5J × 14 size, filling the inner pressure with 2.0 Kgf / Cm ² , and then applying a load (normal inner pressure, load) of 440 Kg on a flat plate. The distances e and f between the lateral sipes in Examples 1 and 3 were both set to 5.4 mm. As a matter of course, the sipes 11 shown in FIGS. 2, 3 and 4 are provided uniformly for all the blocks on both shoulder-block rows.

The test tire was subjected to the above-mentioned internal pressure and load conditions indoors, and the rolling resistance was measured by the coasting method at a speed of 200 Km / H. When the result is shown as a value at a speed of 80 km / H, the comparative tire was 2.80 (100), while Examples 1, 2, and 3 were 2.69 (96) and 2.
The values 66 (95) and 2.63 (94) were obtained.
In this way, rolling resistance is effectively reduced by using a sipe to alleviate circumferential shear strain and / or axial shear strain that occurs axially outside the ground contact end of the shoulder block in the contact area during running. Can
When both strains are alleviated simultaneously more positively, a more remarkable effect can be obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a tire according to the present invention.

FIG. 2 is a partial plan view of a tire according to the present invention.

FIG. 3 is a partial plan view of another embodiment of the present invention.

FIG. 4 is a partial plan view of another embodiment of the present invention.

[Explanation of symbols]

 1 Tire 2 Sidewall 3 Tread 4 Circumferential groove 5 Lug groove 6 Block 7 Block row 11 Sipe

Claims (1)

[Claims] 1. A tire having a land portion divided into a plurality of grooves in a cylindrical tread portion extending over a pair of left and right side walls, and a land portion located on a shoulder of the tread portion. A pneumatic tire having a sipe provided in a portion axially outward from a ground contact end position.