JP2003312208A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of increasing a rigidity near a bead and near a shoulder and further improving an operational stability in particular while keeping a superior riding comfortable condition by changing a chord angle at a carcass layer for every location at the tire. <P>SOLUTION: This pneumatic tire has a pair of annular beads 1a, a carcass layer 10 having both ends wound back at the beads 1a and a belt layer 6 for reinforcing the carcass layer 10 below a tread 4, wherein the extremity end PE of a wound-back segment 12 of the carcass layer 10 is arranged near the end part of the belt layer 6. The wound-back segment 12 has a first slope part 12A with a chord angle θ<SB>1</SB>being 20° or more and 85° or lower, a radial part 12B with a chord angle θ<SB>2</SB>being 85 to 90° and a second slope part 12C with a chord angle θ<SB>3</SB>being 20° or more and 85° or lower from its bead side toward its extremity end, and interface lines of each of the radial parts are arranged at one position by 20 to 40% and the other position by 60 to 80% of a tire sectional height. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire in which a tip of a winding portion of a carcass layer is arranged near an end portion of a belt layer and a cord angle of the winding portion changes in each region.

[0002]

2. Description of the Related Art Radial tires, which are currently the mainstream of pneumatic tires, have been reinforced between a pair of annular beads.
The carcass layer in which a plurality of cords are arranged in the tire radial direction (the meridian direction) and the carcass layer located below the tread are reinforced by the hoop effect, and the cords are provided with a plurality of belt layers inclined with respect to the tire circumferential direction. The structure is general. The carcass layer has a large rigidity in the tire radial direction but a small rigidity in the circumferential direction, and the belt layer has a large rigidity in the tire circumferential direction but a small rigidity in the radial direction.

For this reason, local stress concentration is likely to occur at the belt end near the boundary between the carcass layer and the belt layer,
It reduced the durability of the tire. In addition, it is generally known that in cornering traveling, when the slip limit is reached, the reaction force may suddenly be lost, resulting in an uncontrollable state.

On the other hand, in the bias tire existing before the radial tire, since the rigidity of the tread portion is insufficient and the cornering reaction force is not sufficient, the exercise ability is inferior, and the cord is bent on the tire side where bending occurs during running. Due to the crossing, shear strain occurs between the layers, which easily causes fatigue failure, and the ride comfort is not sufficient.

Therefore, in order to make up for the above-mentioned drawbacks of both tires, in JP-A-61-263805, the cord of the carcass layer located below the tread is greatly inclined from the meridian direction and located on the tire side. A pneumatic tire has been proposed in which two carcass layers having cords arranged in a radial direction are laminated so that inclined cords cross each other, and a reinforcing layer having cords arranged in the tire circumferential direction is provided on the outer peripheral surface thereof. There is. Further, as a method for producing a ply for forming such a carcass layer, a ply having a plurality of cords linearly arranged is attached to a molding drum having a plurality of cylindrical drums coaxially, and then a cylinder is formed. A method of partially changing the cord angle of the ply by providing a predetermined deflection angle between the drums is disclosed. The cylindrical ply obtained in this way, after bead driving,
The tubular airbag is inserted, shaped into a donut shape by the internal pressure, and then the circumferential reinforcing layer is attached.

[0006]

However, since the above-mentioned tire is manufactured by the above-mentioned manufacturing method, it is difficult to obtain a tire in which the cord angle is complicatedly changed for each part of the tire. Therefore, for example, the cord angle of the carcass layer near the bead and the carcass layer near the tire maximum width are almost the same, and when the tire maximum width is arranged radially, the rigidity near the bead becomes insufficient, It was necessary to carry out the same reinforcement as for radial tires. Such reinforcement around the beads has led to an increase in tire weight and a complicated manufacturing process.

On the other hand, for the purpose of improving the steering stability, the tip of the rewinding portion of the carcass layer is arranged below the belt layer to increase the lateral rigidity and improve the steering stability of the pneumatic tire (supermarket). Also known as high turn-up tires) is known. In addition, JP-A-2000-33
Japanese Patent No. 5207 discloses that the cord angle of the cord disposed in the sidewall portion of the carcass layer of the pneumatic tire and the winding portion is 65 to 85 ° and the cords of both cords intersect. Proposed. However, in a pneumatic tire with its sidewalls uniformly inclined, shear strain occurs between layers due to cord crossing at the tire side where bending occurs during running, fatigue breakdown easily occurs, and riding comfort is sufficient. I couldn't say.

Therefore, an object of the present invention is to change the cord angle of the carcass layer for each part of the tire.
It is an object of the present invention to provide a pneumatic tire capable of improving the steering stability by increasing the rigidity in the vicinity of the bead and the shoulder while maintaining a good riding comfort.

[0009]

The above object can be achieved by the present invention as described below.

That is, the pneumatic tire of the present invention comprises a pair of annular beads, a carcass layer whose both ends are rewound by the beads, and a belt layer which reinforces the carcass layer below the tread. In the pneumatic tire in which the tip of the winding portion of the carcass layer is arranged in the vicinity of the end portion of the belt layer, the winding portion has a cord angle formed by the cord and the tire circumferential direction from the bead side to the tip side.
The first inclined part of not less than 85 ° and less than 85 ° and the cord angle of 85 to 9
It has a radial portion of 0 ° and a second inclined portion having a cord angle of 20 ° or more and less than 85 °, and the first boundary line between the first inclined portion and the radial portion is 20 to 40% of the tire cross-sectional height.
The second boundary line between the radial portion and the second inclined portion is arranged at a position of 60 to 80% of the tire cross-sectional height.

In the above, the tip of the winding portion is
It is preferable that it is arranged on the tire equator line side from the end side of the maximum width layer of the belt layer and between the maximum width layer and the carcass layer.

[Advantages] According to the pneumatic tire of the present invention, since the radial portion is provided in the region near the tire maximum width, it is possible to maintain good riding comfort and the bead side of the region. Since the one inclined portion is provided, the rigidity near the bead can be increased and the steering stability can be improved. Further, since the second inclined portion is also provided on the tread side of the radial portion, rigidity near the shoulder can be increased. As a result, in particular, it is possible to provide a pneumatic tire in which the rigidity in the vicinity of the bead and in the vicinity of the shoulder is increased and the steering stability is improved, while maintaining a good riding comfort.

When the tip of the winding portion is located on the tire equator line side from the end side of the maximum width layer of the belt layer and is arranged between the maximum width layer and the carcass layer, The tip is less likely to separate, and the durability of the tire can be further improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional view showing an example of the pneumatic tire of the present invention, and FIG.
Is a side view schematically showing the carcass layer, and FIG. 2B is an explanatory view schematically showing the arrangement of the cords of the carcass layer.

As shown in FIG. 1, the pneumatic tire of the present invention comprises a pair of annular beads 1a, a carcass layer 10 having both ends rewound by the beads 1a, and the carcass layer 1 thereof.
Belt layer 6 for reinforcing 0 under the tread 4. The pneumatic tire has a cross-sectional structure that is symmetrical or substantially symmetrical with respect to the equator line CL. In this embodiment, the carcass layer 10 is composed of one layer, and the bead 1 a of the carcass layer 10 is formed.
An example in which the code of the main body 11 in between is a radial is shown.

As shown in FIG. 2, in the main body portion 11 between the beads 1a of the carcass layer 10, the cord angle formed by the cord 11a and the tire circumferential direction PD is 85 to 90 °. This point is the same as a normal radial tire, and together with the belt layer 6, the riding comfort, durability, exercise performance, and the like of the radial tire can be suitably expressed. Carcass layer 10
The cords that make up are rayon, polyester,
Examples thereof include organic fibers such as polyamide and aromatic polyamide, and steel.

The belt layer 6 is composed of an upper layer 6b and a lower layer 6a.
Although the layered structure can be exemplified, the angle of the cord forming each layer with respect to the tire equator line CL is preferably 10 to 35 °. Further, a fiber reinforcing layer having cords arranged in the circumferential direction may be provided on the upper surface of the upper layer 6b. The cord material forming the belt layer 6 may be any material conventionally used for the belt layer 6, such as steel or organic fibers such as aromatic polyamide.

In the present invention, the tip PE of the rewinding portion 12 of the carcass layer 10 is arranged near the end of the belt layer 6. In the present embodiment, the tip PE of the winding portion 12 is closer to the tire equator line CL side than the edge of the maximum width layer (lower layer 6a in the illustrated example) of the belt layer 6 and is the maximum width layer and the carcass layer 10. An example of being arranged in between is shown.

In the present invention, the winding portion 12 of the carcass layer 10 has a first inclined portion 12A, a radial portion 12B, and a second inclined portion 12C from the bead side toward the tip side, as shown in FIG. Have. The first inclined portion 12A has a cord angle θ ₁ between the tire circumferential direction PD and the cord 12a of 20.
The angle is at least ° and less than 85 °, but is preferably at least 45 ° and less than 85 °. The radial portion 12B has a cord angle θ ₂ between the tire circumferential direction PD and the cord 12b of 85 to 90 °.
The second inclined portion 12C includes the tire circumferential direction PD and the cord 12c.
The cord angle θ _{3 of} is between 20 ° and less than 85 °,
It is preferably 45 ° or more and less than 85 °. The first inclined portion 1
The cords 12a to 12c of the 2A, the radial portion 12B, and the second inclined portion 12C may be constant or change in angle within the above cord angle range.

A first boundary line between the first inclined portion 12A and the radial portion 12B is arranged at a position of 20 to 40% of the tire section height H, and a second boundary between the radial portion 12B and the second inclined portion 12C. The line is arranged at a position of 60 to 80% of the tire cross-section height H.

In the present embodiment, an example is shown in which the first inclined portion 12A and the portion arranged along the bead filler 1b (area portion having the height H1) coincide with each other. The height H1 of the bead filler 1b is preferably 20 to 50% of the tire cross-section height H in order to enhance the effect of improving steering stability by improving lateral rigidity. The hardness (after vulcanization) of the bead filler 1b is preferably 80 to 98 ° in JISA hardness.

Further, in this embodiment, as shown in FIG. 1, a chafer 21 for reinforcing the outside of the carcass layer 10 around the bead is provided. These may be rubbers with increased hardness or those reinforced with long fibers or short fibers.

Except for the above points, the radial tire has substantially the same structure. That is, as shown in FIG. 1, both ends of the carcass layer 10 are folded back by a bead 1a, and a bead filler 1b having a high rubber hardness is arranged between the rewinding part 12 of the carcass layer 10 and the main body part 11. The part 1 is formed. Further, similar to a normal tire, a sidewall rubber 2a is arranged on the outer side of the carcass layer 10, an inner liner rubber 3 is arranged on the inner side, and a tread 4 made of a tread rubber is arranged on the outer side of the belt layer 6, A predetermined pattern is formed on the outer peripheral surface of 4.

Examples of the raw material rubber for the rubber layer and the like include natural rubber, styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR) and the like. These rubbers are reinforced with a filler such as carbon black or silica, and are appropriately blended with a vulcanizing agent, a vulcanization accelerator, a plasticizer, an antioxidant and the like. Steel wire is used as the bead wire,
In order to improve the adhesiveness with rubber, surface treatment or adhesion treatment is usually performed.

The pneumatic tire of the present invention is manufactured in the same manner as a normal pneumatic tire except that a ply for a carcass in which the cord angle of the winding portion of the carcass layer is partially changed from the tire radial direction is used. Can be manufactured. The above-mentioned carcass ply is formed into a cylindrical shape. For example, after a bead is arranged, a tubular airbag is inserted and shaped into a donut shape by the internal pressure, and then the belt layer 6 is formed by a conventional method.

In the carcass ply, for example, while supplying a rubber-coated cord, a device for attaching the tip of the cord to a tray with a desired path by a driving attachment roller is used. 8-24413
In the manufacturing method described in Japanese Patent Publication No. 5, the carcass ply can be manufactured by making both ends (carcass tip end portions) of the cord angles radial.

The method of forming the carcass ply using the former device will be further described as follows. That is, by using the device as shown in FIG. 4, the cord material 40 is pulled by the roller group 43, so that the cord material 40 is fed from the bobbin 41 while passing through the mouthpiece portion 42a of the extruder 42 for covering rubber. The cord covered with the vulcanized rubber and coated with the rubber is fed between the cushioning rollers 44a of the cushioning section 44 and becomes loose. The tip of the rubber-covered cord is attached to the tray 47 in a desired path by the attaching roller 46c provided in the drive unit 46b of the drive mechanism 46, and the length of the cord according to the attached amount is the buffer unit 4.
4 through the guide roller 45. The attachment path is controlled by the position control of the movement of the tray 47 in the longitudinal direction (Y direction) and the position control of the movement of the drive unit 46b that reciprocates the support unit 46a of the drive mechanism 46 (X direction). You can This allows the carcass ply 48
Can be produced on the tray 47. It is convenient to attach the cords without cutting the cords. In this case, two attaching rollers 46c having the same axis and the same height are used.

In order to obtain a desired tire shape and a desired cord angle at each part, it is preferable to appropriately adjust the cord angle when producing the carcass ply. In a bias tire, the relation between the cord angle in the ply state and the cord angle after tire molding can be calculated by the following well-known relational expression (approximate equation), but the relational expression can be similarly applied to the present invention. A can be obtained by determining R of the corresponding portion using as a variable.

Rd cosA = R cosAd Here, Rd is the drum radius, Ad is the cord angle with respect to the circumferential direction on the drum, R is the radius corresponding to the position of the cord after tire molding, and A is the circumferential direction after tire molding. It is a code angle.

[Other Embodiments] Other embodiments of the present invention will be described below.

(1) In the above-described embodiment, an example in which the cords of the first inclined portion and the second inclined portion of the winding portion of the carcass layer are inclined in the same direction with respect to the tire radial direction RD is shown. In the invention, as shown in FIG. 3, the first inclined portion 12A and the second inclined portion 12C of the rewinding portion 12 of the carcass layer 10 are provided.
The cords 12a and 12c may be inclined in the opposite direction to the tire radial direction RD.

(2) In the above-described embodiment, an example is shown in which the winding portion of the carcass layer has a constant cord angle, but in the present invention, even if the cord angle of the winding portion 12 of the carcass layer 10 changes. Good. In that case, the position where the code angle is 85 ° becomes the first boundary line and the second boundary line. The cord angle when the cord angle changes in this way is determined by the cord angle formed by the tangent line of the cord and the tire circumferential direction PD.

(3) In the above-described embodiment, an example in which the cord is also inclined in the outer portion around the bead is shown, but the cord in the portion around the bead may be arranged radially.

(4) In the above-described embodiment, the carcass layer is composed of one layer, and the cord of the main body portion between the beads of the carcass layer has a radial arrangement. However, the cord of the main body portion is partially It may be inclined to, or may be inclined to the whole. However, the cord angle of the portion adjacent to the radial portion of the winding portion of the carcass layer is preferably 85 to 90 °. The other portion may be inclined in the same direction as or opposite to the first inclined portion and the second inclined portion. The cord angle at that time is preferably 45 or more and less than 85 °.

(5) In the above-described embodiment, an example in which the carcass layer is composed of one layer is shown, but in the present invention, the carcass layer may have a two-layer structure. In that case, the carcass layer arranged on the outer side of the winding portion may have a lower tip than the carcass layer arranged on the inner side. Further, in the rewinding portion, the cords of the first inclined portion and the second inclined portion may be inclined in the same direction or the opposite direction, respectively. Further, the plurality of carcass layers may all have the same code angle, or may partially differ.

(6) In the above-described embodiment, the tip of the winding portion is located on the tire equator line side from the edge of the maximum width layer of the belt layer and between the maximum width layer and the carcass layer. Although an example is shown, the tip of the winding portion may be arranged near the end of the belt layer.

[0037]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. In addition, measurement of physical properties and performance evaluation in Examples and the like were performed as follows.

(1) The air pressure of the longitudinally rigid tire is 210 KPa and the load is 510 Kg.
From the state, the force in the vertical direction was applied by the compression test air to measure the bending of the tire when + 10% and −10% of the load was loaded, and the load was divided by the amount of bending to calculate.

(2) The air pressure of the laterally rigid tire is 210 KPa and the load is 510 Kg.
In this state, a lateral force is applied to measure the lateral force-lateral deflection based on the graph, and the load load (51
It was calculated by dividing the lateral force corresponding to 0.3 times 0 kg) by the lateral deflection when the force acts.

(3) Front and rear rigid tires have an air pressure of 210 KPa and a load of 510 Kg.
In the state, the force in the front-rear direction is applied, and the force in the front-rear direction −
Based on the graph of the measured front-back deflection, the front-back deflection force equivalent to 0.3 times the load (510 Kg) was divided by the front-back deflection when the force was applied.

(4) Steering stability Pneumatic tires of size 215 / 45ZR17 obtained in the examples and the like were assembled with a rim at a pneumatic pressure of 220 kPa (rim:
7.0J) and then a real car (2000cc class domestic FR
I attached it to the car. With this actual vehicle, an actual vehicle feeling test (straight running, lane change, handling stability) was carried out by a paneler on a dry test course, and the result was evaluated with an index of 100 as the conventional product. The larger this value, the better the maneuverability.

(5) Similar to the riding comfort and steering stability, an actual vehicle feeling test (running on a good road, running on an irregular road surface, harshness) was carried out by a paneler on a test course in a dry condition. The conventional product was evaluated with an index of 100. The larger this value, the better the riding comfort.

Example 1 A carcass ply having a cord of polyester (1670 dtex / 2) and a driving number of 9 fibers / cm, and a bead filler forming member (JISA hardness after vulcanization 94 °, bottom of triangular section 8 mm, height 35 mm), the main body portion has a cord angle of 90 °, and the first inclined portion of the rewind portion has a cord angle of 6
A carcass layer was formed by winding the bead outward so that the cord angle was 90 ° in the radial portion and the cord angle was 60 ° in the second inclined portion. At this time, the boundary height between the first inclined portion and the radial portion is 30% of the tire sectional height H, and the boundary height between the second inclined portion and the radial portion is 70% of the tire sectional height H.
%Met. Other parts are the same as a normal radial tire, and tire size 215/45 as shown in FIG.
A pneumatic tire of ZR17 was manufactured as a prototype.

Example 2 Using the same carcass ply as in Example 1, the first inclined portion of the rewinding portion has a cord angle of 75 °, the radial portion has a cord angle of 90 °, and the second inclined portion has a cord angle of 75 °. To form a carcass layer that is wound back to the outside with beads, and other parts are the same as a normal radial tire.
A pneumatic tire of 5 / 45ZR17 was prototyped.

Comparative Example 1 (Conventional Product) In Example 1, all the rewound portions of the carcass layer were formed with a cord angle of 90 ° (the cord was radial at all positions), and the other portions were the same as those of a normal radial tire. hand,
A pneumatic tire with the same tire size was prototyped.

Comparative Example 2 In Example 1, the boundary height between the first inclined portion and the radial portion was 15% of the tire section height H, and the boundary height between the second inclined portion and the radial portion was the tire section height. A pneumatic tire having the same tire size was manufactured in the same manner as in Example 1 except that the content of H was 85%.

Comparative Example 3 In Example 1, the boundary height between the first inclined portion and the radial portion was 45% of the tire section height H, and the boundary height between the second inclined portion and the radial portion was the tire section height. A pneumatic tire having the same tire size was manufactured in the same manner as in Example 1 except that the content was 55% of H.

Table 1 shows the results of the above evaluations using the above pneumatic tires.

[0049]

[Table 1] As shown by the results in Table 1, according to the present invention, steering stability can be improved by improving lateral rigidity and longitudinal rigidity while maintaining the riding comfort of the radial tire. On the other hand, in Comparative Example 2 in which the area of the inclined portion was too small, the effect of improving the steering stability was small, and in Comparative Example 3 in which the area of the inclined portion was too large, the riding comfort was poor.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an example of a pneumatic tire of the present invention.

FIG. 2 is a diagram showing a main part of the pneumatic tire of FIG.
(A) is a side view which shows typically a carcass layer, (b) is explanatory drawing which shows the arrangement | positioning of the code | cord typically.

FIG. 3 is a view showing a main part of another example of the pneumatic tire of the present invention, (a) is a side view schematically showing a carcass layer,
(B) is an explanatory view schematically showing the arrangement of the codes

FIG. 4 is a schematic perspective view of an apparatus used for producing a carcass ply.

[Explanation of symbols]

1a bead 1b bead filler 10 carcass layer 11 carcass layer main body part 12 carcass layer rewinding part 12A first inclined part 12B radial part 12C second inclined part 12a first inclined part cord 12b radial part cord 12c second inclined part Code PE Nose H of the rewound portion Tire cross-sectional height PD Tire circumferential direction RD Tire radial direction θ _{1 to} θ ₃ Code angle

Claims (2)

[Claims] 1. A pair of annular beads, a carcass layer whose both ends are rewound by the bead, and a belt layer which reinforces the carcass layer below a tread. In the pneumatic tire arranged in the vicinity of the end of the belt layer, the rewind part has a cord angle formed by a cord and a tire circumferential direction from a bead side to a tip side that is 20 ° or more and less than 85 °. It has an inclined portion, a radial portion having a cord angle of 85 to 90 °, and a second inclined portion having a cord angle of 20 ° or more and less than 85 °, and a first of the first inclined portion and the radial portion.
The boundary line is arranged at a position of 20 to 40% of the tire section height, and the second boundary line between the radial portion and the second inclined part is arranged at a position of 60 to 80% of the tire section height. Pneumatic tire characterized by. 2. The front end of the winding portion is located on the tire equator line side from the end side of the maximum width layer of the belt layer, and is arranged between the maximum width layer and the carcass layer. Pneumatic tire described.