JP4749128B2 - Pneumatic tire - Google Patents

Description

    The present invention relates to a pneumatic tire in which a belt reinforcing layer in which reinforcing elements extending substantially in the circumferential direction are embedded while being bent in a wave shape or a zigzag shape is disposed radially outward of a carcass layer.

As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.
Japanese Patent Laid-Open No. 11-123908

  In this structure, a carcass layer extending in a toroidal shape between a pair of bead cores, and a plurality of reinforcing cords which are disposed radially outside the carcass layer and are inclined with respect to the tire equator S are embedded in the carcass layer. Two belt layers each including a belt ply composed of a belt ply, and a reinforcing element which is disposed between the carcass layer and the belt layer and extends substantially in the circumferential direction while being bent in a wave shape or a zigzag shape with the same phase. The reinforcing element that is bent in a wave shape or a zigzag shape has a total amplitude of 5.0 mm, including a belt reinforcing layer made of the above reinforcing ply and a tread disposed radially outside the belt layer.

    Here, in the conventional pneumatic tire, as the total amplitude of the reinforcing element bent in a wave shape or a zigzag shape, those in the range of 3.0 mm to 5.0 mm are frequently used including the 5.0 mm mentioned above. However, such a conventional pneumatic tire has a tread portion that bulges outward in the radial direction and grows in diameter when filling with normal internal pressure or at high speed, so that the reinforcing element bent in a wavy or zigzag shape is long. It is stretched in the direction (circumferential direction) and deformed so that the total amplitude decreases.

  Then, when the reinforcing element having the same phase is stretched so as to be stretched in this way, a force in the meridian direction (width direction) that is reversed every half wavelength from the reinforcing element is applied to the carcass layer arranged on the radially inner side. As a result, the carcass layer is alternately displaced in the meridian direction, and a large number of undulations (unevenness) are generated in the carcass layer. When the carcass layer is waved in this way, the sidewall portion is affected by this, and circumferential irregularities are generated on the outer surface of the sidewall portion between the tread end and the tire maximum width position, and the pneumatic tire There was a problem that the external appearance of the film was significantly deteriorated.

  An object of this invention is to provide the pneumatic tire which can suppress the unevenness | corrugation which generate | occur | produces in a sidewall part outer surface effectively.

Such a purpose is that a carcass layer extending in a toroidal shape between a pair of bead cores, and a plurality of reinforcing cords that are disposed radially outside the carcass layer and are inclined with respect to the tire equator S are embedded therein. A belt layer comprising at least one belt ply, and at least one reinforcing element which is disposed between the carcass layer and the belt layer and extends substantially in the circumferential direction while being bent in a wavy or zigzag shape. In a pneumatic tire including a belt reinforcing layer made of a single reinforcing ply and a tread disposed radially outward of the belt layer, the total amplitude of the reinforcing element bent in a wave shape or a zigzag shape is 1.2 mm to This can be achieved by setting the reinforcing element within the range of 1.8 mm and the number of repetitions of bending of the reinforcing element within the range of 40 to 60 times per meter .

  In this invention, the total amplitude (width between the maximum value and the minimum value of the bending) of the reinforcing element embedded in the belt reinforcing layer is 1.8 mm or less. Irregularities in the direction can be effectively suppressed. The reason is that if the total amplitude of the reinforcing element is 1.8 mm or less as described above, the reinforcing element is stretched until it becomes a straight line in the middle of filling the regular internal pressure into the pneumatic tire. Although the amount of alternating displacement decreases, if it exceeds 1.8 mm, bending still remains in the reinforcing element even if the internal pressure is filled to the normal internal pressure, and as a result, the amount of alternating displacement of the carcass layer can hardly be reduced. It is thought that.

  However, if the total amplitude of the reinforcing element is less than 1.2 mm, when the pneumatic tire is filled with the normal internal pressure, a large tensile force acts on the reinforcing element that is stretched in a straight line. When running, the reinforcing element breaks (filament breakage). For this reason, the total amplitude of the reinforcing element must be in the range of 1.2mm to 1.8mm.

In addition, if the number of repetitions of bending of the reinforcing element extending in a wavy or zigzag shape is less than 40 per meter, the total length (length along the bending) of the reinforcing element is short, so the pneumatic tire is filled with normal internal pressure. When this occurs, the reinforcing element is stretched in a straight line and a tensile force acts. As a result, when the vehicle runs for a long time under a load, the reinforcing element may break (filament breakage). On the other hand, if it exceeds 60 times, since the total length of the reinforcing element is long, the reinforcing element is stretched to near the normal internal pressure by the internal pressure filling, and this may reduce the amount of alternating displacement of the carcass layer only to some extent. effect but if the number of repetitions of bending of reinforcement elements in the range of 40 to 60 times per 1 m, while effectively suppressing the breakage of the reinforcing elements, the circumferential direction of the irregularities that occur in the sidewall outer surface Can be suppressed.

Further, according to the structure as described in 請 Motomeko 2,3 it can be further strongly inhibited the irregularities that occur in the sidewall outer surface.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, 11 is a flat heavy-duty pneumatic radial tire, and this pneumatic tire 11 has a pair of bead portions 12, and a pair of these bead portions 12 (here, a pair). The bead core 13 may be embedded. The pneumatic tire 11 includes a sidewall portion 14 extending from the bead portion 12 toward the outer side in the substantially radial direction, and a substantially cylindrical tread portion 15 that connects the radially outer ends of the sidewall portions 14 to each other. And further.

  The pneumatic tire 11 has a carcass layer 18 that extends between the bead cores 13 in a toroidal shape and reinforces the sidewall portions 14 and the tread portions 15. Both end portions of the carcass layer 18 surround the bead cores 13. It is folded from the inside to the outside. The carcass layer 18 is composed of at least one, in this case, one carcass ply 19, and inside the carcass ply 19 is a non-stretchable reinforcing cord 20, such as a steel cord, extending substantially in the radial direction (meridian direction). There are many buried. Further, a chafer 21 reinforced with, for example, a steel cord is disposed around the carcass layer 18 in the bead portion 12.

  24 is a belt layer disposed on the outer side in the radial direction of the carcass layer 18 and having a width equal to or slightly narrower than the tread width. The belt layer 24 includes at least one belt ply (here, two belt plies). In the belt ply 25, a large number of non-stretchable reinforcing cords 26 made of, for example, steel or aromatic polyamide are embedded. The reinforcement cord 26 embedded in each belt ply 25 is inclined at a predetermined angle A of, for example, 40 to 70 degrees with respect to the tire equator S, and at least two belt plies 25 have the tire equator S. Are inclined in opposite directions and cross each other.

  28 is a tread made of rubber disposed radially outward of the carcass layer 18 and the belt layer 24. The outer surface (tread surface) of the tread 28 is wide and continuous in the circumferential direction in order to improve drainage performance. Thus, a plurality of main grooves 29, here, five main grooves 29 are formed. In addition, a large number of lateral grooves extending in the width direction or oblique direction may be formed on the outer surface of the tread 28.

  31 is a belt reinforcing layer arranged radially outside the carcass layer 18, more specifically, between the carcass layer 18 and the belt layer 24 so as to overlap the belt layer 24. At least one belt reinforcing layer 31 is provided. Here, it is composed of two reinforced plies 32 laminated. Within each reinforced ply 32, reinforcing elements 34 bent in the same phase in a wave shape or a zigzag shape, for example, a square wave, a triangular wave, and a sine wave in the plane parallel to the front and back surfaces of the reinforced ply 32 have the same phase. The reinforcing elements 34 are substantially embedded in the circumferential direction.

  Here, that the reinforcing elements 34 are in the same phase means that the top and bottom of the peaks of the adjacent reinforcing elements 34 are located on the same straight line extending in the width direction. These reinforcing elements 34 are made of steel, an aromatic polyamide non-extensible material, here steel cord (stranded) or monofilament. In this way, if the reinforcing element 34 extending substantially in the circumferential direction in the belt reinforcing layer 31 is made of steel which is a non-extensible material, the effect of the belt reinforcing layer 31 can be effectively increased, The belt reinforcing layer 31 can be manufactured at low cost.

  As shown in FIG. 3, the above-described reinforcing ply 32 includes, for example, a ribbon-shaped strip 35 having a certain width and covered with rubber by arranging one or a plurality of reinforcing elements 34 in a spiral manner on the outside of the carcass layer 18. It can be configured by winding. If each reinforcing ply 32 is formed in this way, the reinforcing ply 32 (belt reinforcing layer 31) in which the reinforcing element 34 having a wave shape or a zigzag shape is embedded can be manufactured with high accuracy and easily. it can.

  When the pneumatic tire 11 is filled with normal internal pressure or when high speed running is performed after the internal pressure is filled, the tread portion 15 grows in diameter and the reinforcing element 34 is stretched. A force in the meridian direction (width direction) reversing every half wavelength is applied from the reinforcing element 34 to the carcass layer 18 arranged on the radially inner side, and a large number of undulations (unevenness) are generated in the carcass layer 18. For this reason, in this embodiment, the total amplitude Z (the width between the maximum value and the minimum value of the bending) of the reinforcing element 34 is set to 1.8 mm or less.

  The reason is that when the total amplitude Z of the reinforcing element 34 exceeds 1.8 mm, the bending remains in the reinforcing element 34 even when the internal pressure is filled to the normal internal pressure, and as a result, the amount of alternating displacement of the carcass layer 18 is almost reduced. However, if the total amplitude Z is 1.8 mm or less as described above, the reinforcing element 34 is stretched until the pneumatic tire 11 is filled with the normal internal pressure until it becomes a straight line. This is because the amount of alternating displacement is reduced, and the unevenness in the circumferential direction generated on the outer surface of the sidewall portion 14 can be effectively suppressed.

  However, if the total amplitude Z of the reinforcing element 34 is less than 1.2 mm, when the pneumatic tire 11 is filled with normal internal pressure, a large tensile force acts on the reinforcing element 34 that is stretched in a straight line. If the vehicle travels for a long time below, the reinforcing element 34 will break (filament breakage). For this reason, the total amplitude Z of the reinforcing element 34 must be 1.2 mm or more. That is, if the total amplitude Z of the reinforcing element 34 embedded in the belt reinforcing layer 31 is in the range of 1.2 mm to 1.8 mm as in this embodiment, the sidewall of the reinforcing element 34 is suppressed while suppressing breakage. The unevenness in the circumferential direction generated on the outer surface of the portion 14 can be effectively suppressed, and deterioration of the appearance of the pneumatic tire 11 (defective appearance) can be prevented.

Also, number of repetitions N (the number of vibrations) of the bending of the reinforcing element 34 extending in the wavy or zigzag shape you in the range of 40 to 60 times per circumferential 1 m. The reason is that if the number of repetitions N of the bending of the reinforcing element 34 is less than 40 per meter, the total length (length along the bending) of the reinforcing element 34 is short, so the pneumatic tire 11 is filled with normal internal pressure. In this case, the reinforcing element 34 is stretched in a straight line, and a tensile force acts. As a result, if it runs for a long time under load, the reinforcing element 34 may break (filament breakage), but exceeds 60 times. This is because the reinforcing element 34 has a long overall length, and the reinforcing element 34 is stretched to near the normal internal pressure by the internal pressure filling, and this may reduce the amount of alternating displacement of the carcass layer 18 only to some extent. .

  However, if the number N of repetitions of bending of the reinforcing element 34 is within the range of the above-described value, the side wall can be improved while effectively suppressing the breakage of the reinforcing element 34 and improving the durability of the belt reinforcing layer 31. The unevenness in the circumferential direction generated on the outer surface of the portion 14 can be effectively suppressed. Here, the normal internal pressure is the air pressure corresponding to the maximum load (maximum load capacity) in the applicable size / ply rating described in the following standards.

  The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “The Tire and Rim Association Inc. Year Book” in the United States and “The European Tire and Rim Technical Organization's Standards Manual ”corresponds to“ JATMA Year Book of Japan Automobile Tire Association ”in Japan. Note that the total amplitude Z and the number of repetitions N of the reinforcement element 34 described above are measured by peeling off the tread 28 and the belt layer 24 before mounting the pneumatic tire 11 on the rim.

FIG. 4 is a diagram showing Embodiment 2 of the present invention. In this embodiment, a plurality of reinforcing elements 34 bent in a sinusoidal shape are embedded in the ribbon-shaped strip 35, while the reinforcing elements 34 are formed into a plurality of bundles (here, two bundles T1 and T2). At the same time, the phase difference between the reinforcing elements 34 in the adjacent bundles T1 and T2 is 90 degrees or more, here 180 degrees. As a result, when the reinforcing element 34 is deformed to be stretched, the force in the meridian direction (width direction) that is reversed for each half wavelength generated from the reinforcing element 34 causes a mutual force between the bundles T1 and T2 in the ribbon-shaped strip 35. As a result, the unevenness generated on the outer surface of the side wall portion 14 can be more strongly suppressed.

FIG. 5 is a diagram showing Embodiment 3 of the present invention. In this embodiment, a plurality of reinforcing elements 34 that are bent in a sinusoidal shape are embedded in the ribbon-shaped strip 35, and among these reinforcing elements 34, the phase difference between adjacent reinforcing elements 34 is 90 degrees. Above (here, 180 degrees). As a result, when the reinforcing element 34 is deformed to be stretched, a force in the meridian direction (width direction) that reverses every half wavelength generated from the reinforcing element 34 is caused between the adjacent reinforcing elements 34 in the ribbon-shaped strip 35. Therefore, it is possible to cancel the force more finely than the force canceling between the bundles T1 and T2. As a result, the unevenness generated on the outer surface of the side wall portion 14 is further reduced. It can be strongly suppressed. Such a pneumatic tire 11 is suitably used as a pneumatic tire for trucks and buses.

Next, the first test example will be described. In this test, the conventional tire 1 having a structure as shown in FIGS. 1 and 2 having a belt reinforcing layer in which a reinforcing element having a total amplitude Z of 3.0 mm and a repetition number N of 30 is embedded, and the total amplitude Z is The tires 1 to 9 having a structure as shown in FIGS. 1 and 2 each having a belt reinforcing layer in which a reinforcing element in which the number of repetitions N is in the range of 40 to 60 times is embedded in the range of 1.2 mm to 1.8 mm. And a structure as shown in FIGS. 1 and 2 having a belt reinforcing layer in which a reinforcing element having a total amplitude Z outside the range of 1.2 mm to 1.8 mm and a repetition count N of 30 to 70 is embedded. Comparative tires 1 to 7 were prepared.

  Here, the size of each tire is 435 / 50R19.5, and the width of the belt reinforcing layer is 300 mm in all tires, and the diameter of the reinforcing element made of steel embedded in the belt reinforcing layer is 1.8 mm. The width of the inner and outer belt plies constituting the belt layer is 360 mm and 120 mm, the diameter of the reinforcing cord made of steel embedded in the inner and outer belt plies is 1.5 mm, and the inclination angle of the reinforcing cord with respect to the tire equator S is They were 39 degrees to the right and 39 degrees to the left. Further, the remaining specifications of each tire, that is, the total amplitude Z (mm) of the corrugated reinforcing element embedded in the belt reinforcing layer is defined as the amplitude Z, and the number of times of bending (times) per 1 m is repeated. N is shown in Table 1 below.

  Next, in a no-load state in which each of the tires described above is mounted on a rim having a size of 14.00 × 19.5 and filled with a normal internal pressure of 900 kPa, laser light is applied to the tread edge and the tire at the tire end while rotating each tire around the rotation axis. Irradiation was performed on the sidewall portion between the large positions, and the unevenness on the outer surface of the sidewall portion of each tire was measured based on the reflected light. The result is shown as an index with the conventional tire 1 as index 100. In addition, while applying a load of 29.1kN (110% of the maximum load) to each of the tires mentioned above, after running 10,000km on the drum at a speed of 57km / h, each tire was inspected with X-rays and a reinforcing element (filament) The number of ruptures was measured, and the results are shown in Table 1 with the conventional tire 1 as index 100.

  In Table 1, the side unevenness is the former index value, and the element breakage is the latter index value. In addition, the larger the number of side irregularities, the smaller the irregularities on the outer surface of the sidewall portion, while the larger the number of element breakage, the smaller the number of broken steel cords, and the higher the durability. It shows that it is good. As is apparent from Table 1, the unevenness on the outer surface of the sidewall portion of each of the tires is markedly reduced as compared with the conventional tire 1 and the comparative tires 3, 4, and 6.

Further, in all the tires, the number of fractures of the reinforcing elements is hardly decreased as compared with the conventional tire 1, but is significantly decreased in the comparative tires 1, 2, 5, and 7. In the tires 1 to 9 , the rupture indices of the reinforcing elements are 98 and 99. However, this difference does not cause any problem in actual use .

  The present invention can be applied to the industrial field of a pneumatic tire having a belt reinforcing layer in which reinforcing elements extending in the circumferential direction while being bent in a wave shape or a zigzag shape are embedded.

1 is a meridian cross-sectional view of a tire showing Embodiment 1 of the present invention. It is the partially broken top view. It is a partially broken top view of ribbon-shaped strip vicinity. It is a partially broken top view similar to FIG. 3 which shows Embodiment 2 of this invention. It is a partially broken top view similar to FIG. 3 which shows Embodiment 3 of this invention.

11 ... Pneumatic tire 13 ... Bead core
18 ... Carcass layer 24 ... Belt layer
25 ... Belt ply 26 ... Reinforcement cord
28 ... Tread 31 ... Belt reinforcement layer
32 ... Reinforced ply 34 ... Reinforcing element
35 ... Ribbon strip S ... Tire equator T1, T2 ... Bundle Z ... Full amplitude

Claims (3)

A carcass layer extending in a toroidal shape between a pair of bead cores, and at least one belt disposed radially outside the carcass layer and embedded with a plurality of reinforcing cords inclined with respect to the tire equator S A belt layer composed of a ply, and at least one reinforcing ply which is disposed between the carcass layer and the belt layer and in which a reinforcing element extending in a substantially circumferential direction while being bent in a wave shape or a zigzag shape is embedded. In a pneumatic tire including a belt reinforcing layer and a tread disposed radially outward of the belt layer, the total amplitude of the reinforcing elements bent in a wave shape or a zigzag shape is in a range of 1.2 mm to 1.8 mm. In addition, the pneumatic tire is characterized in that the number of repetitions of bending of the reinforcing element is within a range of 40 to 60 times per meter . When the reinforcing ply is configured by winding a rubber-coated ribbon-like strip of a plurality of reinforcing elements bent in a sinusoidal shape, the reinforcing elements are divided into a plurality of bundles, and the pneumatic tire of claim 1, wherein the phase difference was 90 degrees or more beams having adjacent. When the reinforcing ply is formed by spirally winding a ribbon-like strip in which a plurality of reinforcing elements bent sinusoidally are covered with rubber, of these reinforcing elements, adjacent reinforcing elements the pneumatic tire of claim 1, wherein the phase difference was 90 degrees or more.

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