JP4650917B2 - Pneumatic tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire including a carcass layer that reinforces a pair of annular beads and changes the inclination angle of a cord for each portion of the tire.
[0002]
[Prior art]
Currently, radial tires, which are the mainstream of pneumatic tires, reinforce a space between a pair of annular beads, and a carcass layer in which a plurality of cords are arranged in the tire radial direction (meridian direction), and a carcass located below the tread. A structure including a plurality of belt layers in which the layers are reinforced by the hoop effect and the cords are inclined with respect to the tire circumferential direction is common. The carcass layer has high rigidity in the tire radial direction but low rigidity in the circumferential direction. Conversely, the belt layer has high rigidity in the tire circumferential direction but low rigidity in the radial direction.
[0003]
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, and the durability of the tire is reduced. In cornering running, it is generally known that when the slip limit is reached, the reaction force is suddenly lost and the vehicle may become inoperable.
[0004]
On the other hand, with bias tires existing before radial tires, the rigidity of the tread surface is insufficient and there is not enough cornering reaction force, so the exercise ability is inferior, and the cord crosses on the tire side where bending occurs during running As a result, shear strain was generated between the layers, fatigue fracture was likely, and the riding comfort was not sufficient.
[0005]
Therefore, in order to compensate for the drawbacks of both tires as described above, Japanese Patent Application Laid-Open No. 61-263805 discloses that the cord of the carcass layer located below the tread is greatly inclined from the meridian direction, and the cord located on the tire side is provided. There has been proposed a pneumatic tire in which two layers of carcass layers arranged in a radial direction are laminated so that inclined cords cross each other, and a reinforcing layer in which cords are arranged in the tire circumferential direction is provided on the outer circumferential surface thereof. In addition, as a method for producing a ply for forming such a carcass layer, a ply having a plurality of cords arranged in a straight line is attached to a molding drum having a plurality of cylindrical drums on the same axis, and then a cylinder is formed. A method of partially changing the cord angle of the ply by giving a predetermined declination between the drums is disclosed. The cylindrical ply obtained in this manner is inserted into a bead after a bead is driven, shaped into a donut shape by internal pressure, and then a circumferential reinforcing layer is attached.
[0006]
[Problems to be solved by the invention]
However, since the above tire is manufactured by the above manufacturing method, it is difficult to obtain a tire in which the cord angle is changed in a complicated manner for each portion of the tire. For this reason, for example, the cord angles of the carcass layer near the bead and the carcass layer near the tire maximum width are almost the same, and when the vicinity of the tire maximum width is arranged radially, the rigidity near the bead becomes insufficient, Reinforcement similar to radial tires had to be performed. Such reinforcement in the vicinity of the bead has led to an increase in tire weight and a complicated manufacturing process.
[0007]
On the other hand, the present applicant has newly developed and applied for a method for producing a carcass ply for forming a carcass layer in which the inclination angle of the cord changes for each part of the tire (not disclosed at the time of filing this application). According to this manufacturing method, the cord angle can be changed in a complicated manner for each portion of the tire as compared with the above manufacturing method.
[0008]
Therefore, the object of the present invention is to use the advantages of the radial tire and the bias tire in detail for each part of the tire, and in particular, while maintaining good riding comfort, increase the rigidity in the vicinity of the bead and the shoulder, It is an object of the present invention to provide a pneumatic tire that can eliminate or simplify the reinforcing structure.
[0009]
[Means for Solving the Problems]
The above object can be achieved by the present invention as described below.
[0010]
That is, the pneumatic tire according to the present invention is a pneumatic tire including two or more carcass layers that reinforce a space between a pair of annular beads, and an angle formed by a cord constituting the carcass layer and a tire circumferential direction is 90 ±. A region including a position near the maximum width of the tire when a region of 10 ° is a radial region, and a region where the cords of the upper and lower layers intersect at an angle of 10 to 60 ° between the cord and the tire circumferential direction is a bias region And the bias region in any region between the radial region and the bead and in any region between the radial region and the tire equator line. To do.
[0011]
In the above, the ratio of the height from the lower end to the carcass height of the tire cross section, the region of 5-30% is mainly the bias region, and the region of 40-65% is mainly the radial region, 75-95%. It is preferable that this region is mainly used as the bias region. Here, mainly the bias region means that the bias region is 80% or more of the entire area of the designated region, and the same applies to the radial region. In addition, the carcass height of the tire cross section refers to the height at which the lower end is the minimum diameter portion of the winding portion of the carcass layer and the upper end is the maximum diameter portion near the tire equator line of the carcass layer (see Hc in FIG. 1).
[0012]
Further, the radial region reinforced with a belt layer is further provided in a region including the tire equator line, and the bias region is provided in any region between the radial region and the radial region near the maximum tire width. preferable.
[0013]
At that time, in the ratio of the height from the lower end to the carcass height of the tire cross section, a region of 5 to 30% is mainly the bias region, and a region of 40 to 65% is mainly the radial region and 75 to 95%. It is preferable that the region is mainly the bias region, and the tread portion is mainly the radial region.
[0014]
[Function and effect]
According to the pneumatic tire of the present invention, since the radial region is provided in the region including the position near the maximum width of the tire, the riding comfort can be favorably maintained, and the bias region is provided on the bead side of the region. The rigidity of the carcass layer can be increased in the vicinity of the bead, and the steering stability and driving / braking performance can be improved. In addition, since the bias region is provided on the tread side of the radial region, the rigidity of the carcass layer can be increased near the shoulder or near the tread. As a result, by using the advantages of radial tires and bias tires in detail for each part of the tire, the rigidity in the vicinity of the bead and shoulder is increased while maintaining good riding comfort, and the reinforcement structure for that part is unnecessary. A pneumatic tire that can be simplified or simplified can be provided.
[0015]
Further, in the height ratio from the lower end to the carcass height of the tire cross section, the region of 5 to 30% is mainly the bias region, the region of 40 to 65% is mainly the radial region, and is 75 to 95%. When the region is mainly used as the bias region, the bias region, the radial region, and the bias region are sequentially arranged at suitable positions, so that the above-described effect can be obtained more reliably.
[0016]
When the radial region reinforced by a belt layer is further provided in a region including the tire equator line, and the bias region is provided in any region between the radial region and the radial region near the maximum tire width, the belt layer The radial area reinforced with the tire exhibits high rigidity in the tire circumferential direction and width direction, and the bias areas on both sides exhibit moderate rigidity, thereby providing continuity of rigidity with the radial area near the maximum tire width. Can be given. As a result, it is possible to improve the predictability of the slip limit in cornering traveling.
[0017]
The ratio of the height from the lower end to the carcass height of the tire cross section, the region of 5 to 30% is mainly the bias region, the region of 40 to 65% is mainly the radial region, and the region of 75 to 95% is When the bias region is mainly used and the tread portion is mainly used as the radial region, the bias region, the radial region, the bias region, and the radial region are sequentially arranged at suitable positions, so that the above-described effects can be more reliably achieved. It will be obtained.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing an example of the pneumatic tire of the present invention, FIG. 2 (a) is a front view of the partially broken pneumatic tire, and FIG. 2 (b) is a plan view thereof.
[0019]
As shown in FIG. 1, the pneumatic tire of the present invention includes two or more carcass layers 5 that reinforce between a pair of annular beads 1 a. In the present embodiment, an example is shown in which the carcass layer 5 is composed of two layers, an upper layer 5b and a lower layer 5a. In the present invention, a region where the angle θs formed by the cord constituting the carcass layer and the tire circumferential direction PD is 90 ± 10 ° is defined as a radial region RR, and the angle θs formed by the cord and the tire circumferential direction PD (hereinafter referred to as “cord angle”). The region where the codes of the upper and lower layers intersect each other at 10 to 60 ° (absolute value) is defined as a bias region BR. The code angle θs of the upper and lower layers may be slightly different at the intersection.
[0020]
In the present invention, as shown in FIG. 2, a radial region RR is provided in a region including a position near the tire maximum width position PW, and any region between the radial region RR and the bead 1a and the radial region RR are provided. The bias region BR is provided in any region between the tire equator line CL and the tire equator line CL. In the present embodiment, a radial region RR reinforced by the belt layer 6 is further provided in a region including the tire equator line CL, and in any region between the radial region RR and the radial region RR near the tire maximum width PW. An example including a bias region BR is shown.
[0021]
Specifically, in the ratio of the height from the lower end to the carcass height Hc of the tire cross section, a region of 5 to 30% is mainly a bias region BR, and a region of 40 to 65% is mainly a radial region RR. It is preferable that the region of ˜95% is mainly the bias region BR and the tread portion Tr is mainly the radial region RR. In addition, it is preferable to provide an intermediate region that does not correspond to any of the radial region RR and the bias region BR, so that the code angle θs is gradually changed.
[0022]
At this time, the region of 75 to 95% in terms of the height ratio from the lower end to the carcass height Hc of the tire cross section corresponds to the shoulder portion Sh, and it is preferable that the bias region BR is disposed in this portion. In addition, when the edge of the layer (the lower layer 6a in the illustrated example) having the maximum width among the plurality of belt layers 6 is disposed on the bias region BR, it is compared with the case where the end side is disposed on the radial region RR. Further, stress concentration hardly occurs in the vicinity of the end portion of the belt layer 6, and the rigidity continuity with the radial region RR in the vicinity of the maximum tire width is improved.
[0023]
In this embodiment, the belt layer 6 is configured by the upper layer 6b and the lower layer 6a. However, the angle of the cords constituting each layer with respect to the tire equator line CL is preferably 10 to 35 °, and 15 to 25 °. Is more preferable. Moreover, you may provide the fiber reinforcement layer which has arrange | positioned the cord further in the circumferential direction on the upper surface of the upper layer 6b.
[0024]
As the cord material constituting the belt layer 6, any material conventionally used for the belt layer 6 such as an organic fiber such as steel or polyester can be used. Moreover, as a cord material which comprises the said fiber reinforcement layer, organic fibers, such as polyester, polyamide, and aramid, are preferable.
[0025]
The cord angle θs of the bias region BR disposed in the vicinity of the bead 1a is preferably 10 to 60 ° in order to increase the rigidity in the vicinity of the bead 1a and improve the steering stability and the driving / braking performance. Is more preferable. As a result, it is possible to reduce the amount of the bead filler and the reinforcement ply around the bead.
[0026]
Further, the cord angle θs of the bias region BR disposed in the vicinity of the shoulder portion Sh is preferably 10 to 60 °, and more preferably 20 to 50 °, in order to improve the stress dispersion and the continuity of rigidity as described above. . As a result, it is possible to reduce the reinforcement ply around the belt end.
[0027]
The lower carcass layer 5a and the upper carcass layer 5b are laminated so that the cords are arranged at substantially symmetric angles with respect to the tire equator line CL. Examples of the cord constituting the carcass layer 5 include organic fibers such as polyester, polyamide, and polyaramid, or steel.
[0028]
The pneumatic tire of the present invention has substantially the same structure as a normal radial tire except that the cord angle θs of the carcass layer 5 is partially changed as described above. That is, as shown in FIG. 1, both ends of the carcass layer 5 are folded outward by the bead 1a, and a bead filler 1b having a high rubber hardness is disposed between the folded portion of the carcass layer 5 and the main body. Part 1 is formed. Similarly to the normal tire, the side wall rubber 2a is disposed outside the carcass layer 5, the inner liner rubber 3 is disposed inside, and the tread rubber 4 is disposed outside the belt layer 6. A predetermined pattern is formed on the outer peripheral surface.
[0029]
In the present invention, the flatness ratio, which is expressed as a percentage obtained by dividing the tire cross-section height H by the tire maximum width W, is preferably 70% or less. Furthermore, as the flatness ratio becomes 65% or less and 60% or less, cornering performance and the like can be improved by flattening the tire while improving the predictability of cornering traveling and improving safety.
[0030]
The pneumatic tire of the present invention is manufactured in the same manner as a normal pneumatic tire except that carcass plies 8a and 8b in which the cord angle is partially changed depending on the position in the width direction as shown in FIG. Can be manufactured. The two carcass plies 8a and 8b are laminated in a cylindrical shape so that the cords are arranged at substantially symmetric angles with respect to the center line. For example, after the bead is arranged, a tubular airbag is inserted and the internal pressure is increased. After shaping into a donut shape, the belt layer 6 is formed by a conventional method.
[0031]
An outline of a method for manufacturing the carcass plies 8a and 8b shown in FIG. 3 is as follows. Using the apparatus as shown in FIG. 4, the cord material 10 is taken up by the roller group 13, and the cord material 10 is passed from the bobbin 11 while passing through the base portion 12a of the coated rubber extruder 12, and is unvulcanized. The cord covered with rubber is sent between the buffer rollers 14a of the buffer portion 14 and is in a loose state. The tip of the rubber-coated cord is pasted on the tray 17 in a desired path by a pasting roller 16c provided on the drive unit 16b of the drive mechanism 16, and the length of the cord corresponding to the pasting amount is the buffer unit 14 Is taken through the guide roller 15. The pasting path is controlled by position control of movement of the tray 17 in the longitudinal direction (Y direction) and position control of movement of the drive unit 16b reciprocating the support unit 16a of the drive mechanism 16 (X direction). Can do. It is easy to perform the pasting without cutting the cord. In this case, two pasting rollers 16c having parallel axes and the same height are used.
[0032]
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 the carcass plies 8a and 8b are manufactured. In the bias tire, the relationship between the cord angle in the ply state and the cord angle after the tire molding can be calculated by the following well-known relational expression (approximate expression). However, in the present invention, the relational expression can be similarly applied. A can be obtained by determining R of the corresponding part using as a variable.
[0033]
Rd cosA = R cosAd
Here, Rd is a drum radius, Ad is a cord angle with respect to the circumferential direction on the drum, R is a radius corresponding to the position of the cord after tire molding, and A is a cord angle with respect to the circumferential direction after tire molding.
[0034]
[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described.
[0035]
(1) In the above-described embodiment, an example in which the bias region, the radial region, the bias region, and the radial region are arranged in this order from the bead to the tire equator line is shown. However, the bias region, the radial region, and the bias are arranged from the bead to the shoulder. In addition to the arrangement in the order of the areas, the bias area may also be arranged in the tread portion. At that time, in the ratio of the height from the lower end to the carcass height Hc of the tire cross section, a region of 5 to 30% is mainly the bias region, a region of 40 to 65% is mainly the radial region, and 75 to 95. It is preferable that the% region is mainly used as the bias region.
[0036]
In the above case, it is preferable to provide a reinforcing layer in which cords are arranged in the tire circumferential direction without providing a belt layer on the outer peripheral surface of the bias region of the tread portion. The reinforcing layer preferably has a tensile modulus per width that is 1.2 times or more that of the carcass layer. In addition, the reinforcing layer includes a central portion arranged in a range of 45 to 80% of the total width of the tread portion at a lower center position of the tread portion, and side portions on both sides having a low tensile modulus per width with respect to the central portion. It is preferable that the tensile modulus per width of the central portion is 1.2 times or more than the tensile modulus per width of the side portion.
[0037]
Here, the tread surface portion refers to a range inside the ground contact ends on both sides of the tire. Further, the tensile modulus per width of the reinforcing layer is based on the entire width of the reinforcing layer, and the tensile modulus per width of the carcass layer is based on the tread portion, and the initial tensile resistance of the JIS L-1017 chemical fiber tire cord test method. The apparent Young's modulus of the cord was measured according to the degree, and the value obtained by multiplying the number of cords driven per width, the cord cross-sectional area and the number of layers was taken as the tensile modulus. The number of shots is based on the tire after vulcanization, but the number of shots at the material preparation stage can be set from the inflation rate at the time of molding.
[0038]
(2) In the above-described embodiment, the example in which the cords constituting the carcass layer are arranged as shown in FIG. 3 is shown, but various arrangements may be adopted as shown in FIG. FIG. 5 shows only one unit C of the cord of the upper or lower carcass ply.
[0039]
FIGS. 5A to 5B are arranged in line symmetry with respect to the tire equator line CL, and FIGS. 5C to 5D are intersections of the cord and the tire equator line CL. This is a point-symmetric array. In another embodiment (1) described above, for example, a carcass ply having a coding sequence shown in FIG. 5D can be used.
[0040]
(3) In the above-described embodiment, an example in which two carcass layers are provided is shown, but an even number of layers such as four layers may be used. In this case as well, the pair of carcass layers are laminated so that the cords are arranged at substantially symmetric angles with respect to the tire equator line, and the cords of each carcass layer laminated in the same direction are in the same direction at each part. Preferably it is arranged.
[0041]
(4) In the above-described embodiment, the arrangement of the radial region and the bias region for the main body portion of the carcass layer has been described. However, the folded portion of the carcass layer is an intermediate region that does not correspond to the radial region, the bias region, or any of them. Any of these may be arranged. However, in the present invention, from the viewpoint of further increasing the rigidity of the carcass layer in the vicinity of the bead, it is preferable to arrange a bias region also at the folded portion of the carcass layer.
[0042]
At that time, the folded portion may be formed without changing the cord angle of the main body portion of the carcass layer disposed in the vicinity of the bead (see FIG. 5), and is disposed around the bead (the portion circumscribing the bead). Only the carcass layer may be a radial region. Note that the preferred cord angle of the bias region of the folded portion is the same as the cord angle of the main body portion.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an example of a pneumatic tire of the present invention. FIG. 2 is a view showing a main part of the pneumatic tire of the present invention, (a) is a front view of a partially broken pneumatic tire, (B) is a plan view thereof FIG. 3 is a view showing an example of a carcass ply used in the present invention, (a) is a plan view of a ply for a lower layer, and (b) is a plan view of a ply for an upper layer. FIG. 4 is a schematic perspective view of an apparatus used for manufacturing a carcass ply. FIG. 5 is a plan view showing a cord arrangement of another example of a carcass ply used in the present invention.
1a Bead 5 Carcass layer 5a Lower carcass layer 5b Upper carcass layer 6 Belt layer 8a Lower carcass ply 8b Upper carcass ply PW Tire maximum width position RR Radial area BR Bias area H Tire cross section height Hc Tire cross section Carcass height PD Tire circumferential direction CL Tire equator line θs The angle formed by the cord and the tire circumferential direction

Claims (2)

In a pneumatic tire including two or more carcass layers that reinforce a gap between a pair of annular beads, a region where an angle formed by a cord constituting the carcass layer and a tire circumferential direction is 90 ± 10 ° is a radial region, When the angle formed by the cord and the tire circumferential direction is 10 to 60 ° and the region where the cords of the upper and lower layers intersect each other is defined as a bias region,
In the same carcass layer provided with a said radial region in a region including a position near the tire maximum width, to one of the area between the said bead and the radial region comprising the bias region,
A pneumatic tire further comprising the radial region reinforced with a belt layer in a region including a tire equator line, and the bias region in any region between the radial region and the radial region near the maximum tire width . The ratio of the height from the lower end to the carcass height of the tire cross section, the region of 5 to 30% is mainly the bias region, the region of 40 to 65% is mainly the radial region, and the region of 75 to 95% is and primarily the bias region, the pneumatic tire according to claim 1, wherein the tread portion is located mainly as the radial region.

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