JPH0274403A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce rolling resistance without impairing anti-wear and anti- fatigue properties by forming a belt layer of multiple belt plies in the outmost of which organic fiber cord is used for the belt cord. CONSTITUTION:Each belt cord forming a belt layer 7 is inclined as follows: an inner belt ply BI is inclined rightwards up at 75 to 80 deg. in relation to an equator C; a mid No.1 belt ply BM1 at 10 to 20 deg.; a mid No.2 belt ply BM2 is inclined leftwards up at 10 to 20 deg. in relation to the equator C. A ratio of a width WM1 of the mid No.1 belt ply BM1 to a tread width is set at 0.9 or more. In addition, an outer belt ply BO uses organic fiber cord for its belt cord and the inclination of it is set at less than 5 deg. in relation to the equator C of a tire. Thus a restraint of the belt plies in the belt layer is increased to restrain useless movement of the tire on the ground, resulting in reduction of rolling resistance without impairing its anti-wear property.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention increases the restraining force of the rubber layer in the tread portion by specially arranging the belts of the belt layer, without impairing the wear resistance of the tire. The present invention relates to a pneumatic tire that reduces rolling resistance and reduces vehicle fuel consumption.

[Conventional technology]

In recent years, saving fuel for power vehicles has become an issue, and there is an increasing demand for tires that can run with low fuel consumption.

Conventionally, in this type of fuel-efficient tire, rolling resistance has been reduced by using rubber with a small tangential loss, that is, a ratio of loss elastic modulus to dynamic elastic modulus, in the tread portion.

(Problems to be Solved by the Invention) However, although rolling resistance is reduced by using rubber with a small tangent loss as described above in the tread portion, the fatigue resistance of the rubber is reduced and the wear resistance is also poor.Especially A decrease in wear resistance greatly impairs commercial value, and has been a major problem in reducing rolling resistance.

In order to solve the above-mentioned problems, the inventor conducted extensive research and found that (a) a belt layer covering the entire ground contact area of the tread portion should be formed; (b) the outermost part of the belt plies forming the belt layer; The belt ply located at They discovered that by covering other belt plies with a belt ply, rolling resistance can be reduced without impairing fatigue resistance or abrasion resistance.

In the present invention, the belt layer is formed by a number of belt plies, and the outermost belt cord of Peru de Bray is formed using an organic fiber cord, thereby providing rolling resistance without impairing abrasion resistance and fatigue resistance. The purpose of this project is to provide a pneumatic tire that can reduce fuel consumption and power consumption of vehicles.

〔Example〕

In order to solve the above problem, the pneumatic tire of the present invention has a carcass that passes from the trend part through the sidewall part and folds around the bead core of the peed part, and the tread part and radially outward of the carcass. The belt cord of the belt ply BI located on the inside in the radial direction is made of steel and forms an angle of 75° or more and 80° or less with respect to the equator of the tire. The belt cord of the outer belt ply BO, which is located at the outermost side in the radial direction and is inclined at The middle belt ply (BM
) is made of steel and is inclined at an angle of 10 degrees or more and 20 degrees or less with respect to the tire equator, while the outer belt ply (BO) is wider than the other belt plies, and the inner belt ply BM includes a first inner belt ply BMI and a second inner belt ply BM2 arranged inside and outside in the radial direction of the tire, and includes the first inner belt ply BM2 adjacent to the inner belt ply BI. The ratio WM1/WT of BMI belt width WMI and trend width WT is 0.
．． 9 or more, and the belt cord of the inner belt ply Bl and the belt cord of the first inner belt ply BMI are inclined in the same direction, and radially outward of the first inner belt ply. The belt cords of the adjacent second middle belt ply BM2 are tilted oppositely to each other.

[Effect]

In this way, the inner belt ply Bl and the inner belt ply B
Since the belt cord with M is formed using steel, and each belt cord of the belt ply BM1.8M2 in No. 1.2 is tilted oppositely to each other, the belt ply BMI in No. 1.2 is , 8M2 in a triangular truss structure, the rigidity of the tread portion can be increased.

Further, since the width WMI of the first middle belt ply BMI is 90% or more of the tread width WT, substantially the entire tread is reinforced while it is in contact with the ground, and the rigidity of the end portion of the tread portion can be increased.

In addition, the belt cord of the outer belt ply BO is formed from an organic fiber cord, and since the belt cord is inclined at an angle of 5 degrees or less with respect to the equator, the outer belt ply BO forms a triangular truss structure. In order to do so, it is possible to eliminate the tensile phenomenon induced by the cord angle imparted to the second middle belt ply BM2, and to prevent separation from the base tread rubber at the end of the middle belt ply BM. Can be done. In such a belt layer, by increasing the mutual binding force between the belt plies inside, it is possible to suppress unnecessary movement of the rubber layer of the trend part at the ground contact part, without impairing the wear resistance of the tire. Rolling resistance can be reduced.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, the pneumatic tire l of the present invention has bead portions 3.3 on both sides through which the bead core 2 passes, a sidewall 4 extending outward in the radial direction of the tire from the bead portion 3, and a trend portion 5 connecting the upper end of the sidewall 4. It also includes a carcass 6 which passes from the tread part 5 to the sidewall 4 and folds back around the bead core 2 of the repeat part 5, and a bell I-Jif 7 arranged on the outside of the carcass 6 in the tire radial direction.

The carcass 6 is a so-called radial arrangement body in which carcass cords are arranged at an angle of 70° to 90° with respect to the equator C of the tire, and the carcass cords include steel cords, fiber cords such as nylon, polyester, and rayon. will be adopted.

In the belt layer 7, from the carcass 6 side toward the outside in the radial direction of the tire, the inner belt ply Bf, the middle belt ply BM are arranged in this order, and the outer belt ply BO is arranged at the outermost side. The belt ply BM in the text consists of a first middle belt ply BMI and a second middle belt ply BM2 arranged on the inside and outside in the radial direction of the tire. In this way, the belt layer 7 is formed by a plurality of belt plies.

The inner belt ply Bl and the first inner belt ply 48 are both made of highly elastic steel and have a belt cord arranged in a direction inclined to the tire equator C, and are made of rubberized braai. Formed by cutting out.

As shown in Figure 3, the inclination of each belt cord is as follows: the inner belt ply Br is inclined upward to the right at an angle of 75° or more and 80° or less with respect to the tire equator C; Belt ply BM1 tilts upward to the right at an angle of 10" or more and 20' or less with respect to the equator C of the tire.Furthermore, the belt ply BM2 of the second one tilts upward to the left at an angle of 10" or more and 20' or more with respect to the equator C of the tire. Tilt at an angle of less than °.

Therefore, the belt cord of the inner belt ply BT and the belt cord of the first inner belt ply BMI are arranged in the same direction, while the belt cord of the first inner belt ply BMI and the belt cord of the second inner belt ply BMI are arranged in the same direction. The belt ply BMI in the first and second belts is arranged in a different direction from BM2, and the belt ply BMI is 8M.
2 forms a triangular truss structure, and the truss structure can significantly increase the restraining force between the belt plies.

Furthermore, the ratio of the width WMI of the belt ply BMI in the first belt to the tread width WT, that is, WMI/WT is 0.9.
This is the above, and therefore, the belt ply BMI in the first belt can cover substantially the entire area in contact with the tread.

In this way, the inner belt ply Bl, the inner belt ply B
By M, the rigidity of the tread portion 5 can be improved up to the ends of the tread portion.

The outer belt ply BO has its belt cord made of nylon,
It is formed from an organic fiber cord such as polyester or rayon, and therefore has more extensibility than the steel used for the inner belt ply B and the inner belt ply BM.

Manjushri's belt ply BO is the tIJ of its belt cord.
1 is arranged at 5° or less with respect to the equator C of the tire, that is, closer to the circumferential direction of the tire.

The reason why organic fiber cords are used for the outer belt ply BO and the belt cords are arranged close to the direction of the equator C of the tire is based on the following reason.

As described above, the belt layer 7 includes the inner belt ply B I,
As mentioned above, by inclining the respective belt cords of the inner belt ply BM, the rigidity of the tread portion 5 is increased due to their mutual restraining force.Theoretically, the outer belt ply BO is It is not involved in improving rigidity.

However, the belt cord of the second belt ply BM2 has an inclination of 20 degrees or less. Therefore, as long as such a slight inclination exists in the second middle belt ply BM2, a tensile phenomenon may occur in the second middle belt ply BM2. In order to prevent this, an outer belt ply BO is provided that has almost no inclination angle and is made of an organic fiber cord with a low elastic modulus.

Manjushri's belt ply BO has a wider width WO than other belt plies.

Therefore, the outer belt ply BO is the inner belt ply BM.
By suppressing the movement of the inner belt ply Bl due to tension and forming it wide.

The inner belt ply BM can be covered, and peeling that tends to occur at the end of the inner belt ply BM can be prevented.

In this embodiment, the breaker cushion Jii 21 is located inside the belt layer 7 in the tire radial direction, and the tread layer 22 is located outside thereof, and the belt FI 7 has the breaker cushion layer 21 and the tread layer 2.
It will be buried between 2. In the vicinity of the ends of the belt ply BM and the outer belt ply BO in the text, shoulder gaskets 23 with a substantially triangular cross section and low heat generation are arranged to prevent peeling of the ends of the inner belt ply 9 and the outer belt ply 10. Helps prevent.

[Specific Example 1] As shown in Table 1, a plurality of samples with different belt cord inclinations for the inner belt ply Bl, the first inner belt ply BM1, and the second inner belt ply BM2 were prototyped. , we conducted a test to compare the binding force of each.

In addition, during the test, belt plies of the same to medium size were overlapped, and belt plies of conventional specifications were also tested as comparative samples for comparison. The binding force is an index with the conventional specification as 100, and the larger the value, the greater the binding force.

[Specific Example 2] Tires with tire size lO, 00R2014PR with the structure shown in Table 1 were prototyped according to the specifications shown in Table 2, and rolling resistance tests, presence or absence of pull phenomenon, and durability tests were conducted. A model with conventional specifications was also tested.

The test specifications are shown below.

(1) Rolling resistance test Rolling resistance was measured using an indoor drum tester according to the specifications below.

Mounted rim: 7.00Tx20 Tire internal pressure i 7.25KSC Load: 2.425kgf Speed: 80km/Hr The value of the comparative example is set as 100 and is expressed as an index, and the smaller the value, the better.

(2) Investigation of the pull phenomenon A rear-wheel drive truck was equipped with two tires with the same specifications on the left and right sides on the front side, and the truck was driven straight on a test course and evaluated by the driver's feeling.

(3) Durability test A tire with the above specifications was subjected to a load of 140% of the JIS standard value, and the initial speed of 80 km/Hr was increased to 10 km/Hr every 2 hours under the internal pressure of the standard value, and the tire was destroyed. The time up to the final step was expressed as an index. The larger the value, the better. The test was conducted using an indoor drum testing machine.

The results of each test are shown in Table 2. It is shown that all of the examples are better than the comparative examples.

〔Effect of the invention〕

As described above, in the pneumatic tire of the present invention, the inner belt ply is formed by the first and second inner belt plies having belt cords in different directions, and furthermore, the first inner belt ply is relative to the tread width. Since it is 0.9 or more, substantially the entire trend width is reinforced and the rigidity of the end portion of the tread portion can be increased.

The outer belt ply located at the outermost side of the belt layer is
Made of organic fiber cord and with a diameter of 5 to the equator of the tire.
Since the belt is formed to have an inclination of less than 100 degrees and to be the widest, it is possible to prevent HIM between the outer belt ply and the base tread rubber of the inner belt ply. Therefore, the restraining force of the belt ply inside the belt layer increases, suppressing unnecessary movement of the tire at the ground contact area, and reducing rolling resistance without impairing wear resistance, which helps reduce vehicle fuel consumption. Can contribute.

[Brief explanation of the drawing]

Fig. 1 is a right half sectional view showing an embodiment of the present invention, Fig. 2 is a plan view showing the structure of the belt cord developed, and Fig. 3 is a plan view showing the belt structure of a conventional tire. . 2-bead core, 3-bead part, 4-side wall, 5-) red part, 6-...carcass, 7-belt layer, BL-inner belt ply, BO-outer belt ply, BM-inside Belt ply, BM 1-first inner belt ply, BM 2--
1. Belt ply width in 2nd, WT- Trend width, WMI- 1. Belt ply width in 1st.

Claims (1)

[Scope of Claims] 1. A carcass that passes from the tread portion through the sidewall portions and folds around the bead core of the bead portion, and a belt layer disposed in the tread portion and radially outward of the carcass and consisting of a plurality of belt plastics. and the belt cord of the inner belt ply (BI) located radially inside is made of steel and is oriented at 75° to the equator of the tire.
The belt cord of the outer belt ply (BO), which is inclined at an angle of more than 80 degrees and less than 80 degrees and located at the outermost radial direction, is made of organic fiber cord and is 5 degrees
The belt cord of the inner belt ply (BM), which is inclined at an angle of less than As described above, while the belt ply (BO) is tilted at an angle of 20 degrees or less, the outer belt ply (BO) is wider than the other belt plies, and the inner belt ply (BM) is arranged inside and outside in the radial direction of the tire. The tread width (WT) of the first inner belt ply (BM1), which includes a first inner belt ply (BM1) and a second inner belt ply (BM2), is adjacent to the inner belt ply (BI). ) has a ratio WM1/WT of 0.9 or more, and the belt cord of the inner belt ply (BI) and the belt cord of the first inner belt ply (BM1) are inclined in the same direction, and , a pneumatic tire in which belt cords of a second middle belt ply (BM2) adjacent to the radially outer side of the first middle belt ply are inclined oppositely to each other. 2. The pneumatic tire according to claim 1, wherein the belt layer consists of four belt plies.