WO2016024390A1 - Pneumatic tire - Google Patents

Abstract

This pneumatic tire includes a belt that comprises two inclined belt layers which comprise a cord rubber-coated layer which is inclined and extends with respect to the tire circumferential direction, and which are formed as a result of the cords mutually crossing between the two layers. In a state where the pneumatic tire is installed onto an applicable rim, filled to a stipulated internal pressure, and put into a no-load state, the width of the two inclined belt layers in the tire width direction differs, and when, from between the two inclined belt layers, the tire width-direction width of the inclined belt layer which is wide in the tire width direction is set to W1 (mm) and the tire width-direction width of the other inclined belt layer is set to W2 (mm), the ratio W2/W2 satisfies the relational expression 0.25≤(W2/W1) ≤0.8; further, in the tire width-direction cross section of the pneumatic tire which is in the aforementioned state, when the tire radial-direction distance between the tread edge of the pneumatic tire and the tread tread-surface in the tire equator surface of the pneumatic tire is set to d (mm) and the tread width of the pneumatic tire is set to TW(mm), the ratio d/TW is no more than 0.09.

Description

Pneumatic tire

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of reducing the load dependency of the cornering force while maintaining a high cornering force.

Conventionally, as a reinforcement of a pneumatic tire, there is a pneumatic tire in which an inclined belt layer having a cord extending incline with respect to the tire circumferential direction is disposed on the outer side in the tire radial direction of a crown portion of a carcass straddling between bead portions. .

That is, it is practiced to obtain a cornering force, which is one of the important indexes of steering stability, by securing rigidity in the tire width direction by the inclined belt layer.

¡When such a reinforcing structure is adopted, the cornering force increases. However, there arises a so-called load dependency problem in which a difference in the magnitude of the cornering force obtained according to the magnitude of the load applied to the tire occurs. For example, when a pneumatic tire having the above-mentioned reinforcing structure is attached to a small FF vehicle in which the load on the tire differs greatly between the front wheels and the rear wheels, the cornering force obtained at the front wheels can be obtained at the rear wheels. When it is significantly larger than the cornering force to be produced, for example, there is a tendency to oversteer, and there is a problem that steering stability during cornering is lowered.

On the other hand, in Patent Document 1, a circumferential groove is provided in the end region in the tread width direction, and an annular reinforcing material is disposed at the bottom of the circumferential groove, thereby ensuring the rigidity of the tire and the cornering force. There has been proposed a pneumatic tire that does not substantially increase load dependency.

JP 2007-62468 A

However, in the reinforcing structure shown in Patent Document 1, it is necessary to prepare a nylon cord or the like constituting the reinforcing material as a separate member from the pneumatic tire. Moreover, the process of winding a nylon cord etc. around a groove bottom and arrange | positioning is required. Therefore, there is a problem that the manufacturing cost of the pneumatic tire increases. In addition, since the reinforcing material is exposed to the outside, there is a problem in that if the external force is applied to the reinforcing material during traveling, the reinforcing material is broken and sufficient rigidity cannot be obtained. Therefore, there is a demand for a method for improving, that is, reducing, the load dependency of the cornering force without using the reinforcing material as described above.

In view of the above problems, an object of the present invention is to provide a pneumatic tire capable of reducing the load dependency of the cornering force while maintaining a high cornering force.

The gist configuration of the present invention is as follows.
The pneumatic tire of the present invention is a pneumatic tire comprising a rubberized layer of a cord extending obliquely with respect to the tire circumferential direction, and comprising a belt composed of two inclined belt layers in which the cord intersects with each other. In the state where the pneumatic tire is mounted on an applicable rim, filled with a specified internal pressure, and no load is applied, the two layers of inclined belt layers have different widths in the tire width direction, and the two layers of inclined belts Of the layers, when the width in the tire width direction of one of the wide inclined belt layers in the tire width direction is W1 (mm) and the width in the tire width direction of the other inclined belt layer is W2 (mm), the ratio W2 / W1 satisfies the relational expression, 0.25 ≦ (W2 / W1) ≦ 0.8, and in the tire width direction cross section of the pneumatic tire in the above state, the tread end of the pneumatic tire; On the tire equator The ratio d / TW is 0.09 or less, where d (mm) is the distance in the tire radial direction from the red tread surface, and TW (mm) is the tread width of the pneumatic tire. .

“Applicable rim” is an industrial standard effective in the area where tires are produced and used, and is described in JATMA YEAR BOOK in Japan, ETRTO STANDARDDS MANUAL in Europe, TRA YEAR BOOK in the US, etc. The standard rim for the applicable size (Measuring Rim for ETRTO STANDARDDS MANUAL, Design Rim for TRA YEAR BOOK). The “specified internal pressure” refers to an internal pressure corresponding to the maximum load capacity of the tire of the above standard in a tire of an applicable size.

“Tread tread” means the entire tire surface that comes into contact with the road surface when the tire is mounted on an applicable rim and rolled while applying a specified internal pressure and applying a load corresponding to the maximum load capacity. It refers to the outer surface (circumference) surface. The “tread end” refers to the outermost position in the tire width direction of the “tread surface”. The “tread width” refers to the distance in the tire width direction between the “tread ends” when the tire is mounted on an applicable rim, filled with a specified internal pressure, and brought into a no-load state. In addition, when a groove or a recess is formed on the “tread surface on the tire equator surface”, an imaginary line in the tire width direction cross section of the tread surface when it is assumed that the groove or the recess is not formed. A tread contour line is assumed, and the intersection point between the tire equatorial plane and the tread contour line of the tread contour line is indicated.

Here, “extending along the tire circumferential direction”, which will be described later, means that the cord is parallel to the tire circumferential direction or the result of forming a belt layer by spirally winding a strip coated with rubber on the cord. Includes a case where the tire is slightly inclined with respect to the tire circumferential direction (the inclination angle with respect to the tire circumferential direction is 5 ° or less). Further, “the circumferential rigidity of the reinforcing belt” means a unit reinforcement having a unit width in the tire width direction, a unit length in the circumferential direction from the reinforcing belt, and a thickness including all the circumferential belt layers present in the radial direction. When cutting out the belt and applying tension in the extending direction of the cord to the cut out unit reinforcing belt, it is necessary to generate a certain strain in the extending direction of the cord in the cut out unit reinforcing belt. It refers to power. “The circumferential rigidity of the reinforcing belt in the tire width direction region between the end portion of the one inclined belt layer and the end portion of the other inclined belt layer is “Higher than circumferential rigidity” means that the average of “circumferential rigidity of the reinforcing belt in the tire width direction region between the end of the one inclined belt layer and the end of the other inclined belt layer”. It means that it is higher than the average of “the circumferential rigidity of the reinforcing belt inside the tire width direction from the region”.
Furthermore, “the tire width direction region between the end of one inclined belt layer and the end of the other inclined belt layer” is on one half side in the tire width direction with the tire equatorial plane as a boundary. The end of one inclined belt layer and the other inclined side of the inclined belt layer in the tire width direction region between the end of one inclined belt layer and the end of the other inclined belt layer, or the other half side in the tire width direction The tire width direction region between the end portions of the belt layer is indicated.

Here, “the number of the circumferential belt layers provided in the region is larger than the number of the circumferential belt layers provided on the inner side in the tire width direction from the region” means “provided in the region. It means that the average number of layers of the “circumferential belt layer” is larger than the average number of layers of the “circumferential belt layer provided on the inner side in the tire width direction from the region”.

The present invention can provide a pneumatic tire that can reduce the load dependency of the cornering force while maintaining a high cornering force.

1 is a schematic cross-sectional view in the tire width direction of a pneumatic tire according to a first embodiment of the present invention. It is a figure which shows roughly the belt structure of the tire of FIG. FIG. 5 is a schematic cross-sectional view in the tire width direction of a pneumatic tire according to a second embodiment of the present invention. It is a figure which shows roughly the belt structure of the tire of FIG.

As a result of intensive studies to solve the above problems, the inventor of the present invention has a pneumatic tire including a belt composed of two inclined belt layers, and the belt is formed from two inclined belt layers having different widths in the tire width direction. When the cross-sectional shape in the tire width direction of the tread surface is made close to a flat shape, the load dependency of the cornering force may be reduced while maintaining a high cornering force.

First, when the cross-sectional shape of the tread tread surface in the tire width direction is brought close to a flat shape, the contact area increases and the tread deformation increases, so the cornering force increases. On the other hand, when the width of one of the two inclined belt layers is narrowed, the belt rigidity is lowered and the belt is easily displaced in the tire width direction, and the resulting cornering force is reduced. Here, when the load is low, the amount of displacement of the belt during cornering is small. Therefore, at low load, the increase in cornering force due to the decrease in belt rigidity due to the reduction in the width of one belt layer in the tire width direction is due to the increase in the tread deformation due to the tread tread flattening. Small compared to the increase in force. In other words, at low loads, the cornering force contributes greatly to the cornering force as a result of an increase in the tread deformation due to flattening of the tread surface, and the cornering force reduction contributes to a reduction in belt rigidity. The cornering force as a whole is thought to increase.

On the other hand, when the load is high, both the tread deformation and the belt displacement increase. Therefore, the size of the cornering force that increases with the amount of tread deformation and the size of the cornering force that decreases with belt displacement tend to increase. Here, when the load is high, the amount of displacement of the belt during cornering is large. Therefore, the magnitude of the cornering force reduction due to the belt displacement is larger than the magnitude of the cornering force increase due to the tread deformation amount. In other words, when the load is high, the cornering force contributes less to the entire cornering force due to the increase in the tread deformation due to the flattening of the tread surface, and the cornering force due to the lower belt rigidity. The contribution of the reduction is considered to be large. Based on these findings, the inventor of the present invention has found the present invention as a result of further studies on the dimensional ratio of the two inclined belt layers.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view in the tire width direction of a pneumatic tire (hereinafter also simply referred to as “tire”) according to a first embodiment of the present invention. Further, FIG. 1 shows a cross section in the tire width direction of the tire in a state (hereinafter also referred to as “reference state”) in which the tire is mounted on an applicable rim, filled with a specified internal pressure, and is in a no-load state. .

As shown in FIG. 1, a tire (pneumatic tire) 1 according to this embodiment includes a carcass 3 straddling a bead core 2 a embedded in a pair of bead portions 2 in a toroidal shape, and a tire radial direction of a crown portion of the carcass 3. A belt 4 disposed outside and a tread 5 disposed outside the belt 4 in the tire radial direction are provided. The material of the carcass ply cord of the carcass 3 is not particularly limited, and for example, a steel cord or the like can be used.

The belt 4 of the tire 1 according to the first embodiment shown in FIG. 1 includes an inclined belt layer 4a having a width W1 in the tire width direction and an inclined belt layer having a width W2 in the tire width direction that is narrower than the inclined belt layer 4a. 4b. The two inclined belt layers 4a and 4b are belt layers in which the belt cords extend while being inclined with respect to the tire circumferential direction, and the belt cords cross each other between the layers. The material of the belt cord is not particularly limited, but a steel cord is preferably used. One inclined belt layer 4a disposed on the inner side in the tire radial direction has a width W1 in the tire width direction that is wider than a width W2 in the tire width direction of the other inclined belt layer 4b disposed on the outer side in the tire radial direction. Yes. In the present invention, the inclined belt layer 4a is set so that the ratio W2 / W1 between the width W1 of the inclined belt layer 4a and the width W2 of the inclined belt layer 4b satisfies the relational expression 0.25 ≦ (W2 / W1) ≦ 0.8. And the inclined belt layer 4b is comprised. In particular, in the present embodiment, the inclined belt layer 4a and the inclined belt layer 4b are configured so that the ratio W2 / W1 satisfies the relational expression 0.6 ≦ (W2 / W1) ≦ 0.8. Note that the inclined belt layer 4b having a narrow width in the tire width direction may be disposed on the inner side in the tire radial direction, and the inclined belt layer 4a having a large width in the tire width direction may be disposed on the outer side in the tire radial direction.

FIG. 2 is a diagram schematically showing the structure of the belt 4 of the tire of FIG. In the present embodiment, the inclined belt layer 4a is provided such that the inclination angle θ1 of the cord of the inclined belt layer 4a having a wide width in the tire width direction with respect to the tire circumferential direction is 10 ° ≦ θ1 ≦ 30 °. In the present embodiment, the inclined belt layer 4b is provided so that the inclination angle θ2 of the cord of the inclined belt layer 4b having a narrow width in the tire width direction is 10 ° ≦ θ2 ≦ 30 ° with respect to the tire circumferential direction. Note that the inclined belt layer 4a and the inclined belt layer 4b of the present embodiment are provided such that the centers of the inclined belt layer 4a and the inclined belt layer 4b in the tire width direction coincide with the tire equatorial plane CL.

Furthermore, in the tire 1 of the present embodiment, as shown in FIG. 1, the tread 5 sets the distance in the tire radial direction between the tread end TE of the tire 1 and the tread tread surface 5a on the tire equatorial plane CL as d ( mm), and the tread width of the tire 1 is TW (mm), and the ratio d / TW is 0.09 or less. Although not shown in FIG. 1, the tread 5 is formed with a tread pattern having an arbitrary pattern shape including grooves, sipes, and the like.

The tire 1 of the present embodiment further includes a reinforcing belt 6 on the outer side in the tire radial direction of the belt 4 as shown in FIG. The reinforcing belt 6 of this embodiment is composed of two circumferential belt layers 6a and 6b. The circumferential belt layer 6a is configured to cover the entire width of the belt 4 in the tire width direction. The circumferential belt layer 6b is provided separately only in the tire width direction region between the end of the inclined belt layer 4a and the end of the inclined belt layer 4b, of the outer side in the tire radial direction of the circumferential belt layer 6a. It has been. For the circumferential belt layers 6a and 6b, cords made of organic fibers are preferably used. Although not particularly limited, cords made of organic fibers such as aramid, hybrid cords of aramid and nylon, and the like can be used. In the present embodiment, the circumferential belt layer 6b is provided on the outer side in the tire radial direction of the circumferential belt layer 6a. However, the circumferential belt layer 6b may be provided on the inner side in the tire radial direction of the circumferential belt layer 6a.

Hereinafter, the function and effect of the tire of this embodiment will be described.
According to the tire of the present embodiment, first, in the reference state described above, of the two inclined belt layers constituting the belt 4, the width of the inclined belt layer 4a having the wide width in the tire width direction is W1. When the width of the inclined belt layer 4b in the tire width direction is W2, the ratio W2 / W1 satisfies the relational expression, 0.25 ≦ (W2 / W1) ≦ 0.8. In the tire 1 of the present embodiment, the distance in the tire radial direction between the tread end TE of the pneumatic tire 1 and the tread tread surface 5a on the tire equatorial plane CL in the tire width direction cross section of the pneumatic tire 1 in the reference state. When d (mm) and the tread width of the pneumatic tire are TW (mm), the ratio d / TW is 0.09 or less.

As described above, when the load is low, an increase in cornering force due to an increase in the tread deformation caused by the flattening of the tread surface greatly contributes to the entire cornering force, and a decrease in cornering force due to a decrease in belt rigidity results in a decrease in cornering force. The contribution to the entire force is small. In addition, when the load is high, the increase in cornering force due to the increase in tread deformation caused by flattening of the tread surface is less than the contribution to the entire cornering force, and the decrease in cornering force due to a decrease in belt rigidity is reduced. The contribution to the entire cornering force is greater than when the load is low. Therefore, according to the above-described configuration of the present embodiment, the cornering force can be effectively increased by increasing the tread deformation due to the flattening of the tread surface at low loads, and the belt at high loads. The cornering force can be effectively reduced by lowering the rigidity.

As described above, according to the tire of the present embodiment, the load dependency of the cornering force can be reduced while maintaining a high cornering force.

Note that if 0.25> (W2 / W1), the belt rigidity may be too small to obtain a sufficient cornering force. Further, if (W2 / W1)> 0.8, the belt rigidity is not sufficiently lowered, and the load dependency of the cornering force cannot be reduced. Furthermore, if d / TW is larger than 0.09, a sufficient cornering force cannot be obtained at a low load, and the load dependency of the cornering force cannot be reduced.

Here, in the present invention, it is preferable that the ratio W2 / W1 satisfies the relational expression 0.6 ≦ (W2 / W1) ≦ 0.8. When the belt layers 4a and 4b have such a configuration, it is possible to suppress an excessive increase in tire rigidity while maintaining high tire rigidity. Therefore, it is possible to suppress an increase in cornering force at a high load while obtaining a sufficient cornering force.

As shown in the embodiment of FIG. 1, the pneumatic tire of the present invention further includes a reinforcing belt 6 composed of circumferential belt layers 6a and 6b, and the circumferential rigidity of the reinforcing belt 6 is the end of the inclined belt layer 4a. The region in the tire width direction between the belt and the end of the inclined belt layer 4b is preferably higher than the inner side in the tire width direction than this region. Providing such a reinforcing belt 6 can suppress the tire diameter growth in the region between the end portion of the inclined belt layer 4a and the end portion of the inclined belt layer 4b, thereby improving the durability of the tire. it can.
In particular, with respect to the circumferential rigidity defined above, the circumferential rigidity of the reinforcing belt 6 in the region between the end portion of the inclined belt layer 4a and the end portion of the inclined belt layer 4b is reinforced on the inner side in the tire width direction from that region. It is preferable that the circumferential rigidity of the belt 6 is 1.5 to 2.5 times.

As shown in the embodiment of FIG. 1, in the pneumatic tire of the present invention, the number of circumferential belt layers provided in the region between the end of the inclined belt layer 4a and the end of the inclined belt layer 4b is different. It is preferable that the number of the circumferential belt layers provided on the inner side in the tire width direction than this region is larger. If the number of circumferential belt layers is such a relationship, the rigidity in the tire width direction region between the end of the inclined belt layer 4a and the end of the inclined belt layer 4b can be increased with a simple configuration. The rigidity in the region is increased by a method other than increasing the number of circumferential belt layers provided in this region than the number of circumferential belt layers provided on the inner side in the tire width direction from this region. May be raised. For example, by using a cord having a higher Young's modulus than a cord used for a circumferential belt layer in the tire width direction from the region, a cord used for the circumferential belt layer in the region can be used. You may improve the rigidity of the area | region between an edge part and the edge part of the inclination belt layer 4b. The “Young's modulus” is determined in accordance with JIS L1017 8.8 (2002) after testing according to JIS L1017 8.5 a) (2002). Further, the number of strands per unit length in the tire width direction in the tire width direction cross section may be changed, and the number of strands in the tire width direction region is more than the number of strands inside the tire width direction region. You can do more.
In particular, the Young's modulus in the region between the end of the belt layer 4a and the end of the belt layer 4b has the same configuration other than the Young's modulus of the cord, such as the number of layers and the number of strands per unit length. The Young's modulus of the cord inside the tire width direction region is preferably 1.5 to 2.5 times. Similarly, the number of strands per unit length in the tire width direction in the region between the end of the belt layer 4a and the end of the belt layer 4b is the unit length in the tire width direction such as the number of layers and Young's modulus. When the configuration other than the number of hit wires is the same, the number of wires per unit length in the tire width direction inside the tire width direction region is preferably 1.5 to 2.5 times.

Further, as shown in the embodiment of FIG. 1, the pneumatic tire of the present invention has two layers around the tire width direction region between the end of the inclined belt layer 4a and the end of the inclined belt layer 4b. Directional belt layers 6a and 6b are provided, and one circumferential belt layer 6a is preferably provided on the inner side in the tire width direction from this region. With such a configuration, the rigidity of the region between the end portion of the inclined belt layer 4a and the end portion of the inclined belt layer 4b can be increased with a small number of members. The numbers of circumferential belt layers in the region and on the inner side in the tire width direction are not limited to two and one, respectively. For example, the circumferential belt layer may be provided only in the region without providing the circumferential belt layer on the inner side in the tire width direction from the region. Further, for example, three or more circumferential belt layers may be provided in the region. In this case, the difference in the number of circumferential belt layers in the tire width direction from the region and the region may be one layer, It is good also as two or more layers.

Furthermore, in the pneumatic tire of the present invention, as shown in FIG. 2, the inclination angle θ1 of the cord of the inclined belt layer 4a with respect to the tire circumferential direction is 10 ° ≦ θ1 ≦ 30 °, and the cord of the inclined belt layer 4b The inclination angle θ2 with respect to the tire circumferential direction is preferably 10 ° ≦ θ2 ≦ 30 °. If it does in this way, it can control that width direction rigidity becomes low too much, and can control that cornering force at the time of high load becomes too low.

Next, a pneumatic tire according to a second embodiment of the present invention will be described. FIG. 3 is a schematic cross-sectional view in the tire width direction of the pneumatic tire 1 according to the second embodiment of the present invention, and FIG. 4 is a diagram schematically showing the structure of the belt 4 of the tire of FIG. It is. In the description of the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted. Moreover, in FIG.3 and FIG.4, in order to understand easily, each structural member is shown typically. As shown in FIG. 3, the pneumatic tire of the second embodiment does not include a reinforcing belt. Further, the width W2 of the inclined belt layer 4b is further reduced with respect to the width W1 of the inclined belt layer 4a as compared with the embodiment of FIG. The ratio W2 / W1 with the width W2 in the tire width direction of the belt layer 4b satisfies the relational expression, 0.25 ≦ (W2 / W1) ≦ 0.6. Also in the tire of the second embodiment configured as described above, the load dependency of the cornering force can be reduced by the same effect as the effect of the first embodiment.

In the pneumatic tire of the present invention, as shown in FIG. 3, the ratio W2 / W1 of the width W2 of the inclined belt layer 4b to the width W2 of the inclined belt layer 4b with respect to the width W1 of the inclined belt layer 4a is 0. .25 ≦ (W2 / W1) ≦ 0.6 is preferably satisfied. If the inclined belt layers 4a and 4b are configured in this way, the rigidity of the shoulder area of the tread can be lowered, so that the cornering force can be prevented from being reduced due to the tread treading when the load is low, and the load dependency of the cornering force is further reduced. can do.

FIG. 4 is a diagram schematically showing an example of the structure of the belt 4 of the tire of FIG. In the present embodiment, the inclined belt layer 4a is provided so that the inclination angle θ1 of the inclined belt layer 4a with respect to the tire circumferential direction of the cord is 30 ° ≦ θ1 ≦ 85 °. In the present embodiment, the inclined belt layer 4b is provided so that the inclination angle θ2 of the cord of the inclined belt layer 4b with respect to the tire circumferential direction is 10 ° ≦ θ2 ≦ 30 ° and θ1> θ2. .

If the inclination angle θ1 of the cord in the inclined belt layer 4a with respect to the tire circumferential direction is set to 30 ° or more, the elongation of the rubber in the tire circumferential direction when the tread tread surface 5a is deformed increases. As a result, the cornering force is further increased. Note that the upper limit of the inclination angle θ1 is 85 ° from the viewpoint of securing the bending rigidity in the tire circumferential direction.

However, when the inclination angle θ1 of the cord of the inclined belt layer 4a is increased, the noise performance outside the vehicle tends to deteriorate due to the change in the vibration mode of the tire. More specifically, many of the tires in which the cords of the inclined belt layer are inclined at an angle of 30 ° to 85 ° with respect to the tire circumferential direction, the primary, secondary, and In the vibration mode such as the third order, the tread surface has a shape that vibrates uniformly uniformly, so that a large radiation sound is generated. Such a radiated sound can be a problem particularly in a tire for a passenger car that is expected to be used at a high speed of 60 km or more and has a high demand for noise performance from customers.

Therefore, if the inclination angle θ2 of the cord of the inclined belt layer 4b with respect to the tire circumferential direction is set to be smaller than the inclination angle θ1 of the cord of the inclined belt layer 4a and is in the range of 10 ° to 30 °, the tire equator Since the out-of-plane bending rigidity in the tire circumferential direction in the vicinity of the surface CL is appropriately maintained, it is possible to improve the change in the vibration mode and suppress the deterioration of the outside noise performance. That is, as a result of suppressing the spread of the tread 5 in the tire circumferential direction in the vicinity of the tire equatorial plane CL, such radiated sound can be reduced. Therefore, in addition to improving the load dependency of the cornering force, the noise performance outside the vehicle can be improved.

In addition, by setting the inclination angle θ2 to 10 ° or more, the out-of-plane bending rigidity in the tire circumferential direction can be maintained without hindering the effect of ensuring the contact length in the inclined belt layer 4a. Further, by setting the inclination angle θ2 to 30 ° or less, it is possible to reliably suppress the above-described deterioration of the outside noise performance.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

In order to confirm the effect of the present invention, tires according to Invention Examples 1 to 5 and tires according to Comparative Examples 1 to 3 were made as trial products. The specifications of each tire are shown in Table 1 below. The tire sizes are all 225 / 50R17. Each tire was subjected to a test for evaluating the load dependency of the cornering force, noise outside the vehicle, and tire durability.
As shown in FIGS. 1 and 3, each tire includes a carcass locked to a bead core embedded in a pair of bead portions, and two layers provided on the outer side in the tire radial direction of the crown portion of the carcass. A tire including an inclined belt made of an inclined belt layer and a tread.

<Cornering Force>
The tires of the above invention examples and comparative examples were assembled on a rim (size: 7.5J-17), applied with an internal pressure of 220 kPa, mounted on the vehicle, and measured with a flat belt cornering tester. In addition, the cornering force obtained under two different load conditions, that is, the load conditions corresponding to 80 and 30% of the load conditions corresponding to the maximum load capacity in the application size / ply rating was measured with the belt speed of 100 km / h. .

<Reinforcing belt rigidity>
The rigidity of the reinforcing belt was evaluated as a × E1, where the Young's modulus of the reinforcing belt fiber was E1 and the number of drivings per belt unit width was a.

<External vehicle noise test>
The tires of Invention Example 4, Invention Example 5 and Comparative Example 2 are mounted on a vehicle under the same conditions as described above, and the drum is rotated at a speed of 100 km / h on the running test drum, and the microphone is moved. The noise level was measured using the formula. The results are shown in Table 1. The results are evaluated based on the difference in noise level from that of Comparative Example Tire 2 (± 0). A larger number of “↓” means better noise reduction effect. Inventive Example 1-3, Comparative Example 1 and Comparative Example 3 were not subjected to an outside noise test.

<Tire durability>
The amount of damage generated inside and outside the tire after running a fixed distance on a drum tester with the tires of the above invention examples and comparative examples assembled on a rim (size: 7.5J-17) and an internal pressure of 220 kPa. The durability is evaluated by comparing the size of the crack size.

The results are shown in Table 1. The value of the cornering force is an index evaluation with the tire cornering force being 100 when the load of the comparative example tire 2 is 30%. In addition, it has shown that a cornering force is so large that an index | exponent is large. In addition, by referring to α / β (%) in the table, it can be seen that the load dependency of the cornering force is high or low. A smaller value indicates a lower load dependency.

As shown in Table 1, the tires according to Invention Examples 1 to 6 are improved in the load dependency of the cornering force while maintaining a higher cornering force than the tires according to Comparative Examples 1 to 3. I understand. On the other hand, in Comparative Example 1, although the load dependency of the cornering force is improved, the cornering force obtained at the time of high load is remarkably lowered, and the high cornering force cannot be maintained. In Comparative Example 2 and Comparative Example 3, the cornering force can be maintained high, but the load dependency of the cornering force is not improved sufficiently. Comparing Invention Example 1 and Invention Example 2, the load dependency of the cornering force is reduced in Invention Example 1 in which θ1 and θ2 are 10 ° or more and 30 ° or less. Although not shown in Table 1, due to the difference in the number of circumferential belt layers, the rigidity of the reinforcing belt in the region of the end of the inclined belt layer 4a and the end of the inclined belt layer 4b is increased from the inside of this region. Inventive Example 1 and Inventive Example 2 which were also increased, good tire durability was obtained as compared with Inventive Example 3. Comparing Invention Example 4 and Invention Example 5, it can be seen that Invention Example 4 with 30 ° ≦ θ1 ≦ 85 °, 10 ° ≦ θ2 ≦ 30 °, and θ1> θ2 is superior in outside noise performance.

1: tire (pneumatic tire), 2: bead part, 3: carcass, 4: belt, 4a, 4b: inclined belt layer, 5: tread, 5a: tread surface, 6: reinforcement belt, 6a, 6b: circumferential direction Belt layer, TE: Tread edge, CL: Tire equator, TW: Tread width

Claims (8)

A pneumatic tire comprising a rubberized layer of a cord extending obliquely with respect to the tire circumferential direction, and comprising a belt comprising two inclined belt layers in which the cord intersects with each other;
Attach the pneumatic tire to the applicable rim, fill the specified internal pressure,
The two inclined belt layers have different widths in the tire width direction,
Of the two inclined belt layers, the width in the tire width direction of one of the wide inclined belt layers in the tire width direction is W1 (mm), and the width in the tire width direction of the other inclined belt layer is W2 (mm). ), The ratio W2 / W1 is the relational expression 0.25 ≦ (W2 / W1) ≦ 0.8.
And
In the tire width direction cross section of the pneumatic tire in the above state, the distance in the tire radial direction between the tread end of the pneumatic tire and the tread surface on the tire equator surface is d (mm), and the tread width of the pneumatic tire is A pneumatic tire characterized by having a ratio d / TW of 0.09 or less, where TW (mm). The pneumatic tire according to claim 1, wherein the ratio W2 / W1 satisfies the relational expression 0.6 ≦ (W2 / W1) ≦ 0.8. The belt further includes a reinforcing belt composed of one or more circumferential belt layers composed of a rubberized layer of a cord extending along a tire circumferential direction on the tire radial direction outside of the belt,
The circumferential rigidity of the reinforcing belt in the tire width direction region between the end portion of the one inclined belt layer and the end portion of the other inclined belt layer is the circumference of the reinforcing belt on the inner side in the tire width direction from the region. The pneumatic tire according to claim 1, wherein the pneumatic tire is higher than directional rigidity. The pneumatic tire according to claim 3, wherein the number of circumferential belt layers provided in the region is greater than the number of circumferential belt layers provided on the inner side in the tire width direction from the region. The pneumatic tire according to claim 4, wherein two circumferential belt layers are provided in the region, and one circumferential belt layer is provided on the inner side in the tire width direction from the region. 2. The pneumatic tire according to claim 1, wherein an inclination angle θ of the inclined belt layer with respect to a tire circumferential direction of the cord is 10 ° ≦ θ ≦ 30 °. The pneumatic tire according to claim 1, wherein the ratio W2 / W1 satisfies the relational expression 0.25 ≦ (W2 / W1) ≦ 0.6. The inclination angle θ1 of the cord of the one inclined belt layer with respect to the tire circumferential direction and the inclination angle θ2 of the cord of the other inclined belt layer with respect to the tire circumferential direction are:
30 ° ≦ θ1 ≦ 85 °,
10 ° ≦ θ2 ≦ 30 °, and
θ1> θ2
The pneumatic tire according to claim 7, wherein

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