JP3419881B2 - Pneumatic tire - Google Patents

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.

[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 consumption by the stress / strain cycle associated with the rolling of the tire, and the tire is extended to the bead portion and radially outward from the bead portion. Comparing the energy consumption by side part and tread part located across both side parts, it is found that the tread part has the largest energy consumption, so the tread part is significantly impaired in other important characteristics such as wear resistance. In order to reduce rolling resistance from the rubber surface of the tread part, use a rubber suitable for rolling resistance within the range where it does not wear, or bury the above rubber in the base part of the tread that does not appear on the surface throughout the wear life. Has been.

[0003]

According to a detailed investigation by the inventor of the behavior of the tire on the ground contact surface when the tire is running, when the tire rotates and the tread portion enters the contact area, the tire approaches the shoulder block. The buttress portion (upper side wall) that undergoes expansion deformation that significantly extends in the circumferential direction and compression deformation that includes bending that pushes the shoulder portion of the tread portion toward the equatorial plane of the tire. As a result, the heat generation temperature of this part stands out because it acts as a circumferential and axial shear strain inside this part periodically when viewed partially and continuously when viewed as a whole. It was found that the loss in this case greatly affects the rolling resistance of the tire. Therefore, it has been found that by reducing the energy consumption of the buttress portion connected to the tread, the rolling resistance of the tire can be effectively reduced without changing the tread rubber which has been conventionally used.

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

[0005]

According to the pneumatic tire of claim 1, a pair of sidewalls and a tread portion extending between the sidewalls are connected in a toroidal shape, and the periphery of each portion is formed. A rubber-covered tire, the buttress adjacent to the tread portion of the sidewall is provided with a plurality of goug portions at intervals in the circumferential direction, and the goug portion has a circumferential length y.
20 to 40 mm, radial length x is set to 10 to 30 mm
And the circumferential distance d of the above-mentioned cutout is set to 30-40 mm
It is characterized by being. Claim 2
The invention provides the pneumatic tire according to claim 1, wherein
The notched portion is recessed relatively long in the circumferential direction, and the major axis is in the circumferential direction.
It is almost oval-shaped, or rectangular with rounded four corners.
Butt from both the radial and circumferential ends of the bottom.
The depth is reduced toward the outer surface of the lobe.
It is characterized by

[0006]

According to the pneumatic tire of the present invention, the buttress portion of the sidewall adjacent to the tread is provided with a plurality of cutout portions in which the covering rubber is cut out at intervals in the circumferential direction. Therefore, as described above, the cyclic shear strain in the circumferential direction and the axial direction that occurs in the buttress when the tread portion passes through the contact area during traveling is effectively suppressed,
As a result, it is possible to achieve a reduction in rolling resistance by reducing the loss in this portion. Regarding the undercut of the buttress, it is conceivable to use a groove-shaped notch that connects endlessly in the circumferential direction.However, depending on the notch method, the rigidity of that part may decrease, and the bending strain due to the increase in bending rather increases, which is expected. Rolling resistance does not decrease so much, and problems often occur in terms of durability. As in the tire according to the present invention, the cutouts are provided at intervals, and the cutouts are circumferentially arranged.
Direction length y is 20 to 40 mm, and the length of the cutout is x in the radial direction.
Is 10 to 30 mm, and the circumferential distance d of the cutout is 30 to 40
When the thickness is set to mm, it is possible to suppress an undesired increase in bending, so that there is no problem in durability and good results are obtained for the purpose of the present invention. In addition, the engraved part is the circumference
It is a relatively elliptical hollow with a major axis facing the circumferential direction.
Shape, or a rectangle with four rounded corners, in the radial direction of the bottom, and
From both ends in the circumferential direction toward the outer surface of the buttress section.
It is possible to have a shape in which the depth is reduced to the beam.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An explanation will be given below with reference to the drawings. 1 is a partial sectional view of a tire showing an embodiment of the present invention, and FIG. 2 is a partial side view of the tire shown in FIG. Tire 1 in the figure
Has a pair of side walls 2 and a tread portion 3 extending in a cylindrical shape that straddles both side walls 2 in a toroidal shape, and the periphery thereof is covered with a covering rubber or a covering rubber 4. ing. Although the right half of the tire is omitted in the figure, it is symmetrical with respect to the equatorial plane O 2. Reference numeral 5 is a bead ring embedded in the tip of the side wall 2,
A carcass 6 with its ends wound up around it extends through the region of the side wall 2 and the tread part 3 and between the carcass 6 and the tread part 3 the width of this tread part. A belt layer 7 extending over the entire area is arranged and reinforced. The carcass 6 is composed of at least one ply in which fiber cords typified by polyester, rayon and nylon are arranged at about 90 ° (radial) with respect to the equatorial plane O. , Steel and /
Alternatively, a non-extensible code such as aramid may be used with respect to the equatorial plane O.
At least two plies that are inclinedly arranged at an angle of 0 ° to 30 ° are superposed so that the cords of the plies intersect with each other, and a heat-shrinkable cord such as nylon is wrapped around the main trunk layer 8. A structure including an auxiliary layer 9 formed by spirally winding a plurality of (rubbered ribbon-like bodies) substantially parallel to the equatorial plane O can be applied.

In the present invention, the tire sidewall 2
The buttress 10 adjacent to the tread portion 3 is provided with a plurality of cutout portions 11 in the tire circumferential direction at circumferential intervals d. The cut-out portion 11 is a substantially elliptical shape with the major axis y facing the circumferential direction, a rectangular shape with four corners rounded, and a recess which is relatively elongated and recessed in the circumferential direction. The bottom B, which corresponds to the deepest part of the cutout 11, corresponds to the part where the shear strain generated in the coating rubber of the buttress 10 during running is the largest, and the buttress from both the radial and circumferential ends of the bottom B. It has a shape in which the depth is gradually reduced toward the outer surface of 10.

In the normal running, the cutout 11 must be provided away from the grounding end E of the tread, and the distance f between the upper end P of the cutout and the grounding end E is 5 to 15 mm for this purpose.
The range is appropriate. Here, the ground contact edge refers to the tire
This is the grounding end when the normal internal pressure and load specified by the JATMA standard are applied on a flat plate. Width or minor diameter x
The length or major axis y depends on the tire size, but is preferably 10 to 30 mm and 20 to 40 mm, respectively. The reason is that the width x of the cutout portion is within the numerical range corresponding to the shear strain generation area in the covering rubber of the buttress portion, and the length y is related to the circumferential distance d of the cutout portion 11 and is 20 mm. If it does not satisfy the above condition, the engraved area is too narrow to effectively block the deformation, and the expected reduction in rolling resistance cannot be obtained. On the other hand, if it exceeds 40 mm, the range becomes too wide and durability becomes a problem as in the case of continuous scooping, which is also not preferable. Therefore, the distance d is 30 ~
40 mm is preferable, and in this range, it is more preferable to make the cutout length y and the cutout mutual interval d substantially equal to each other, or to set the distance d to be slightly larger. The maximum depth of the engraved part is preferably 30% or more of the maximum thickness of the part. However, for the bottom B, the carcass 6 located near this
It is necessary to separate at least 1 mm from the reinforcing layers such as the belt layer 7 and so the upper limit of the depth is determined by itself.

[0010]

[Effect] To confirm the effect of the tire according to the present invention 185 /
Using a 65R14 size passenger car tire, a comparative product 1 in which an endless groove is provided at the same position as the invention product of the left and right buttresses with a width x in the present invention product in which the cutout portions shown in FIGS. The rolling resistance and the durability test were conducted together with the comparative product 2 having no cutout portion or groove in the buttress portion and evaluated. In preparing a test tire, the carcass has a radial structure with two polyester cord plies, and the belt layer has a steel cord ply with two trunk layers and one nylon cord auxiliary layer added to the trunk layer. Was commonly used. Table 1 shows the details of the above-mentioned cutouts and grooves and the test results. In the test, as the rolling resistance measurement condition, an internal pressure of 2.0 Kgf / Cm ² ,
A load of 440 kgf was applied, and an elliptical method was performed on a steel drum having a smooth surface having a diameter of 1707 mm. In the endurance test, after running for 2 hours at a speed of 100 Km / H at room temperature of 35 ° C, the speed was increased by 10 Km / H for 30 minutes, and the speed at breakage and the running time were compared. Then, the invention product was set to 100, and when the value was larger than this value, the durability was good, and when the value was small, the durability was bad.

[0011]

[Table 1]

As described above, by arranging a plurality of goug portions in the circumferential direction at intervals in the buttress of the tire, which undergoes a great amount of internal shear strain during running, rolling resistance is advantageous without sacrificing durability. Can be reduced to.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a partial side view of the tire shown in FIG.

[Explanation of symbols]

1 tire 2 side wall 3 Tread section 4 Coated rubber 10 buttress 11 Egg section

Claims (2)

(57) [Claims] 1. A tire in which a pair of sidewalls and a tread portion extending across both sidewalls are continuous in a toroidal shape, and the periphery of each of these portions is covered with rubber, and the tread portion in the sidewall is formed. A plurality of cutout portions are provided at intervals in the circumferential direction on the buttress close to, and the cutout portion has a circumferential length y of 20 to 40 mm and a radial direction.
The length x in the direction is set to 10 to 30 mm, and the circumferential distance d of the cutout is set to 30 to 40 mm.
And it is, the pneumatic tire, characterized in that. 2. The cutout portion is a recess relatively long in the circumferential direction.
The major axis is an elliptical shape with the major axis facing in the circumferential direction, or the four corners are rounded.
Is a rectangular shape, and the radial and circumferential directions at the bottom
From both ends to the outer surface of the buttress section
2. The sky according to claim 1, wherein the height is reduced.
Favorite tire.