JP2009241720A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability, traction performance, and external appearance of a pneumatic tire 11. <P>SOLUTION: A belt reinforcing layer 42 in which a steal code 44 extending substantially parallel to a tire equator S is buried is arranged in a central portion in a width direction of a tread portion 15, and a reinforcing layer 30 in which a reinforcing code 33 made of an organic fiber is buried is arranged in each of both ends portions in the width direction. In this structure, when a diameter of a tread end portion 31 is reduced while shrinking in a circumferential direction for molding a green tire, the reinforcing code 33 with low bending rigidity in a shrinking direction becomes hardly resistance. Hence, the diameter of the tread end portion 31 can be reduced almost without becoming wavy. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to a pneumatic tire having a tread portion having a belt reinforcing layer in which a steel cord extending substantially parallel to the tire equator S is embedded.

As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.
JP-A 49-57503

  This includes a carcass layer extending in a toroidal shape between a pair of bead cores, a belt layer that is disposed radially outside the carcass layer and has a belt cord that is inclined with respect to the tire equator S embedded therein, An organic fiber cord such as nylon, which is disposed between the tread disposed radially outside the belt layer and between the belt layer and the tread and extends substantially parallel to the tire equator S, is embedded in the belt layer. A belt reinforcement layer that is wide, and the effect of the belt reinforcement layer improves traction performance and suppresses the tread diameter growth during high-speed running to improve high-speed durability. It is.

  In recent years, as the performance of passenger cars has increased, further traction performance and high-speed durability have been demanded. Therefore, the organic fiber cords embedded in the belt reinforcement layer described above are not stretchable with high tensile strength. Instead of steel cords, attempts have been made to meet the aforementioned demands by further enhancing the effect of the belt reinforcing layer.

  And such a pneumatic tire, for example, because the expansion of the tread portion during vulcanization is strongly limited by the steel cord embedded in the belt reinforcing layer, the belt layer on the cylindrical band forming drum, A belt reinforcing layer and a tread are pasted one after another to form a belt tread band having a belt reinforcing layer having a diameter substantially the same as the diameter in the center in the width direction of the belt reinforcing layer of the product tire. The green tire can be formed by being attached to the outside of a tire intermediate body made of a carcass layer or the like that is bulged and deformed in a substantially toroidal shape, and then the green tire is vulcanized.

    Here, since the crown portion of the tire intermediate body to which the belt tread band is attached has a substantially arc shape with a smaller diameter toward the both ends in the axial direction, when the belt tread band is attached to the crown portion, Both end portions in the width direction of the belt tread band are squeezed radially inward along the curvature of the crown portion. As a result, a large circumferential contraction force is applied to both end portions in the width direction of the belt reinforcing layer.

  At this time, since the steel cord embedded in the belt reinforcing layer has high rigidity in the shrinking direction, the steel cord has a large amplitude in the radial direction along the circumferential direction together with other tire constituent members. By waving at the wavelength, the aforementioned shrinkage is absorbed. When a green tire having a large undulation at the end of the tread is vulcanized as a product tire in this way, the aforementioned undulation remains in the product tire, so that a load acts on the peak of the undulation during driving. As a result, there is a problem that the strain generated at the end of the belt layer increases and the durability is lowered.

  In addition, since the amplitude and wavelength of the undulations differ from tire to tire, the product tires vary in shape and the desired tire performance cannot be obtained, or the appearance of the tires deteriorates and the work is complicated. There was also the problem of becoming. For this reason, it is conceivable to reduce the width of the belt reinforcing layer and eliminate the belt reinforcing layer from the end of the tread, thereby preventing the occurrence of the waviness. There is a problem that the diameter growth at the end cannot be sufficiently suppressed and the high-speed durability is lowered.

  An object of the present invention is to provide a pneumatic tire capable of improving the appearance while improving durability and traction performance.

    The purpose is to provide a carcass layer extending in a toroidal shape between the pair of bead cores, and a belt layer in which a belt cord that is disposed radially outside the carcass layer and is inclined with respect to the tire equator S is embedded. And a tread disposed radially outward of the belt layer, a pair of reinforcements disposed so as to overlap both ends of the belt layer in the width direction and embedded with reinforcing cords made of organic fibers inside And a belt reinforcing layer disposed between the belt layer and the tread and extending from at least one reinforcing layer to the other reinforcing layer and having a steel cord embedded therein and extending substantially parallel to the tire equator S This can be achieved by a pneumatic tire provided with

  In the present invention, a reinforcing cord made of organic fibers is embedded in a pair of reinforcing layers arranged so as to overlap both end portions in the width direction of the belt layer, while being arranged between the belt layer and the tread, and at least By embedding a steel cord extending substantially parallel to the tire equator S in the belt reinforcing layer extending from one reinforcing layer to the other reinforcing layer, the shrinking direction bending rigidity of the reinforcing layer is reduced. The rubber at the tread end is a reinforcing layer (reinforcement cord) even if the tread end is reduced in diameter and a circumferential contraction force is applied as described above when molding a green tire. It is deformed so as to be compressed in the circumferential direction with almost no resistance and thicken the gauge, and absorbs the aforementioned contraction force.

  As a result, the tread end portion can be reduced in diameter with almost no undulations, so that the contact pressure at the tread end portion during running of the product tire becomes almost uniform, and the distortion at the belt layer end portion is reduced. Durability can be improved. Moreover, as described above, since there is almost no undulation, the shape of the product tire is substantially uniform and the appearance is good, and a tire having a desired performance can be easily manufactured, and the work can be simplified. it can.

  Furthermore, since the steel cord of the belt reinforcement layer extending substantially parallel to the tire equator S is embedded in the center portion in the width direction of the tread portion, the diameter growth at the time of high speed running of the portion is strongly suppressed, Traction performance is improved by the large bending rigidity. On the other hand, since the reinforcing cord of the reinforcing layer is embedded in the tread end portion, the diameter growth of the tread end portion during high-speed running can be effectively suppressed.

  Further, when configured as described in claim 2, shear deformation at both ends in the width direction of the belt layer during traveling can be suppressed, and cracks and separation at the belt end can be strongly suppressed, and reinforcement can be achieved. Since the outer end in the width direction of the layer is continuous by being folded, cracks and separation at the portion can be strongly suppressed. Furthermore, if comprised as described in Claim 3, the circumferential direction tensile rigidity of a reinforcement layer can be made high enough, and the diameter growth of the tread edge part at the time of high-speed driving | running | working can be suppressed strongly.

  According to the fourth aspect of the present invention, the reinforcing layer in the portion overlapping the belt reinforcing layer can be constrained by the belt reinforcing layer. It is possible to suppress a situation in which the portion floats outward in the radial direction. Furthermore, if comprised as described in Claim 5, the rising in the width direction inner end part of a reinforcement layer can be suppressed strongly, suppressing the wavy in a tread edge part strongly.

  According to the sixth aspect of the present invention, the belt reinforcing layer having a high circumferential rigidity can be disposed close to the outer peripheral surface (tread surface) of the tread portion having a great influence on the traction performance. The tire traction performance can be effectively improved. Furthermore, if comprised as described in Claim 7, the circumferential direction rigidity of a reinforcement layer will become high enough, and the diameter growth of this tread edge part at the time of high-speed driving | running | working can be suppressed strongly.

Embodiment 1 of the present invention will be described below with reference to the drawings.
In FIGS. 1 and 2, reference numeral 11 denotes a pneumatic radial tire for a passenger car that can run at high speed. The pneumatic tire 11 forms a pair, here, a bead portion 13 in which a pair of bead cores 12 are embedded, and these beads. Side wall portions 14 respectively extending substantially radially outward from the portion 13, and a substantially cylindrical tread portion 15 that connects the radially outer ends of the sidewall portions 14 are provided. The present invention may be applied to pneumatic tires for aircraft or trucks / buses.

  The pneumatic tire 11 has a carcass layer 18 that extends between the bead cores 12 in a toroidal shape and reinforces the side wall portions 14 and the tread portions 15. Both end portions of the carcass layer 18 in the width direction of the bead core 12 It is wrapped around. The carcass layer 18 is composed of at least one carcass ply 19 in this case, and the carcass ply 19 intersects the tire equator S at a cord angle of 70 to 90 degrees, that is, in a radial direction ( A large number of mutually parallel carcass cords 20 made of polyester, nylon, aromatic polyamide, steel, etc. (here, polyester) extending in the meridian direction are embedded.

  23 is a belt layer arranged radially outward of the carcass layer 18, and this belt layer 23 has at least two belt plies, here two belt plies 24, 25 in this order toward the radially outer side. It is configured by stacking. Here, a plurality of mutually parallel belt cords 26 and 27 are respectively embedded in the belt plies 24 and 25, and these belt cords 26 and 27 are made of steel strands or monofilaments, and at least Two adjacent belt plies 24, 25 are inclined in the opposite direction with respect to the tire equator S and intersect each other. The belt cords 26 and 27 in the belt plies 24 and 25 are inclined at the same inclination angle with respect to the tire equator S, and the inclination angle is in the range of 45 to 75 degrees.

  Reference numeral 30 denotes a pair of reinforcing layers arranged at the tread end portion 31 so as to overlap both ends in the width direction of the belt layer 23. Each reinforcing layer 30 is composed of at least one reinforcing ply 32 here. . The reinforcing layer 30 has a hold structure that wraps around both ends in the width direction of the belt layer 23 (all belt plies 24 and 25) by folding back around the center in the width direction. A large number of parallel reinforcing cords 33 are embedded.

  Here, as the reinforcing cord 33 embedded in the reinforcing layer 30, organic fibers such as polyester, nylon, and aromatic polyamide are used. Among them, if aromatic polyamide is used, the reinforcing layer 30 is pulled in the circumferential direction. This is preferable because the rigidity can be sufficiently increased and the diameter growth of the tread end portion 31 during high-speed running can be strongly suppressed.

  The reinforcing layer 30 having the above-described hold structure is formed by sticking a strip-like member in a cylindrical shape on the outer side in the radial direction of the carcass layer 18, and then in the radial direction of the inner side in the width direction of the carcass layer 18 between the strip-like members The belt layer 23 is affixed to the outer side, and the belt-like member outside the widthwise portion 36 in the widthwise direction is centered on the folded portion 36 slightly away from the widthwise outer ends of the belt layer 23. Can be formed by overlapping the belt layer 23 on the outer side in the radial direction.

  Thus, if the reinforcing layer 30 has a hold structure, the reinforcing layer 30 includes an inner portion 37 positioned radially inward from the belt layer 23, and an outer portion positioned radially outward from the inner portion 37 and the belt layer 23. The portion 38 and the inner portion 37 and the outer portion 38 in the width direction outer end are continuous with each other, and the folded portion 36 is located slightly outside the tread end 39 in the width direction. As described above, if the pair of reinforcing layers 30 with high circumferential rigidity reinforced with the organic fiber reinforcing cords 33 are disposed so as to overlap each other in the width direction both ends of the belt layer 23, the tread end portions during high-speed running The diameter growth of 31 can be effectively suppressed.

  Further, if the reinforcing layer 30 wraps both ends in the width direction of the belt layer 23, the belt cords 26 and 27 inclined in the opposite direction are deformed so that the tread portion 15 becomes flat when traveling, so that the tire equator S Even when trying to deform to the side, such deformation is strongly constrained by the reinforcing layer 30, and as a result, shear deformation occurring at both ends in the width direction of the belt layer 23 is suppressed, and cracks and separation at the belt end are strong. To be suppressed. In addition, since the outer end in the width direction (folded portion 36) of the reinforcing layer 30 is folded and continuous, it is possible to strongly suppress cracks and separation in the folded portion 36.

  Furthermore, it is preferable that the inclination angle of the reinforcing cord 33 embedded in the reinforcing layer 30 with respect to the tire equator S is 30 degrees or less. The reason is that if the inclination angle is 30 degrees or less, the circumferential rigidity of the reinforcing layer 30 is increased, and the diameter growth of the tread end 31 during high-speed running can be strongly suppressed, and high-speed durability is improved. Because. For this reason, it is more preferable that the inclination angle is 0 degree, that is, the reinforcing cord 33 extends substantially parallel to the tire equator S.

  A belt reinforcing layer 42 is narrower than the belt layer 23 (the narrowest belt ply 25). The belt reinforcing layer 42 is disposed in close contact with the outer side in the radial direction of the belt layer 23. Between the at least one reinforcing layer 30 and the other reinforcing layer 30. Here, the belt reinforcing layer 42 is composed of at least one (here, one) reinforcing ply 43, and a steel cord 44 extending substantially parallel to the tire equator S is embedded in the reinforcing ply 43. Has been.

  In this way, the reinforcing cords 33 made of organic fibers are embedded inside the pair of reinforcing layers 30 arranged so as to overlap the both ends in the width direction of the belt layer 23, while being arranged between the belt layer 23 and a tread 46 described later. By embedding a steel cord 44 extending substantially parallel to the tire equator S in a belt reinforcing layer 42 extending from at least one reinforcing layer 30 to the other reinforcing layer 30, the bending rigidity in the shrinking direction of the reinforcing layer 30 is increased. Since the bending strength in the shrinkage direction of the belt reinforcing layer 42 is significantly reduced, the tread edge 31 is not affected even when the tread edge 31 is reduced in diameter and a circumferential shrinkage force is applied as described above. The rubber located at the position is compressed in the circumferential direction with almost no resistance from the reinforcing layer 30 (reinforcing cord 33) and deforms so that the gauge becomes thick, and absorbs the aforementioned contracting force.

  As a result, the tread end portion 31 can be reduced in diameter with almost no undulation, whereby the contact pressure of the tread end portion 31 during running of the pneumatic tire 11 becomes substantially uniform and at the end portion of the belt layer 23. Distortion is reduced and belt durability can be improved. Moreover, as described above, since there is almost no undulation, the shape of the product tire is substantially uniform and the appearance is good, and a tire having a desired performance can be easily manufactured, and the work can be simplified. it can.

  Further, since the steel cord 44 of the belt reinforcing layer 42 which is substantially parallel to the tire equator S and has a high effect is disposed in the center portion in the width direction of the tread portion 15, the radius of the portion during high-speed running is arranged. Diameter growth outward in the direction is strongly suppressed, and traction performance is improved by a large bending rigidity.

  In this embodiment, by making the width of the belt reinforcing layer 42 larger than the distance between the two reinforcing layers 30, both the outer ends in the width direction of the belt reinforcing layer 42 and the reinforcing layer 30 (the outer portion 38). ) In the radial direction in close contact with the inner end in the width direction, but in this way, it is possible to restrain the reinforcing layer 30 where the belt reinforcing layer 42 overlaps, It is possible to suppress a situation in which the inner end in the width direction of the reinforcing layer 30 is lifted outward in the radial direction during high-speed traveling.

  Here, the distance L in the width direction in the overlapping region between the reinforcing layer 30 and the belt reinforcing layer 42 described above is preferably in the range of 3 to 30 mm. The reason is that if the distance L in the width direction is less than 3 mm, the inner end in the width direction of the reinforcing layer 30 may be lifted during high speed running, while if the distance L exceeds 30 mm, the end of the tread Although there is a risk of undulations at 31, if the distance L is in the range of 3 to 30 mm, the undulation at the tread end 31 is strongly suppressed and the lifting of the inner end of the reinforcing layer 30 in the width direction is suppressed. Because it can be done.

  In this embodiment, the belt reinforcing layer 42 is disposed on the radially outer side of the reinforcing layer 30 (the inner end in the width direction of the outer portion 38) in the overlapping region where the reinforcing layer 30 and the belt reinforcing layer 42 overlap each other. However, in this way, the belt reinforcing layer 42 having a high circumferential rigidity can be disposed close to the outer peripheral surface (tread surface) of the tread portion 15 having a large influence on the traction performance. As a result, the air The traction performance of the entering tire 11 can be effectively improved.

  Here, the above-described belt reinforcing layer 42 is formed by, for example, winding a strip of a certain width in which one or several steel cords 44 are lined up and covered with rubber, and spirally wound around the belt layer 23 and the reinforcing layer 30. Can do. If the belt reinforcing layer 42 is formed in this way, the belt reinforcing layer 42 can be formed with high efficiency and high accuracy. 46 is a tread made of rubber disposed radially outside the belt layer 23, the reinforcing layer 30, and the belt reinforcing layer 42. The outer surface (tread surface) of the tread 46 has a wide width to improve drainage performance. A plurality of main grooves 47 extending in the circumferential direction, here, four main grooves 47 are formed. In addition, a large number of lateral grooves extending in the width direction or the oblique direction may be formed on the outer surface of the tread 46.

    In the above-described embodiment, only the width direction both ends of the belt layer 23 are wrapped by the reinforcing layer 30, but in the present invention, both width direction both ends of the belt layer and the belt reinforcing layer are wrapped by the reinforcing layer. In this case, the reinforcing layer overlaps the outside of the belt reinforcing layer in the radial direction. Moreover, in this invention, you may comprise a reinforcement layer from the normal ply which a meridian cross section does not fold and extends in a substantially axial direction.

    Next, test examples will be described. In this test, a pair of reinforcing layers in which both ends in the width direction of the belt layer are wrapped in a tread portion and a reinforcing cord made of polyester is embedded inside, and both ends in the width direction are distance L (15 mm) between both reinforcing layers. 1 and 2 with a belt reinforcing layer that overlaps only, and a tire that is the same as the tire 1 except that the reinforcing cord in the reinforcing layer is made of aromatic polyamide. 2 and a conventional tire 1 similar to the embodiment tire 1 except that the reinforcing layer described above was omitted and the width of the belt reinforcing layer was the same as the distance between the outer ends of the reinforcing layer in the width direction.

  Here, each of the tires described above was a tire for a high-performance passenger car, and the size was 225 / 45R16. The tire skeleton structure is arranged on the outer side in the radial direction of the carcass layer, the carcass layer including two carcass plies embedded with a polyester cord that intersects the tire equator S at 90 degrees. A belt layer composed of an inner belt ply in which a steel cord of 50 degrees rising to the left is embedded, and an outer belt ply in which a steel cord of 50 degrees rising to the right is embedded, Both the reinforcing cord and the steel cord embedded in the reinforcing layer and the belt reinforcing layer extend substantially parallel to the tire equator S.

  Next, each of the tires described above was manufactured by vulcanizing a green tire formed by the method described in the prior art, and the occurrence of undulations at the tread edge was confirmed. As a result, in the conventional tire 1, a wave with an arithmetic average of 3 mm of the total amplitude occurred, but in the tires 1 and 2, the occurrence of the wave was not confirmed.

  Next, after filling each tire with an internal pressure of 200 kPa, a high-speed durability test was performed by pressing the drum against a drum with a camber angle of 1.5 degrees and a slip angle of 0 degrees while applying a load of 6 kN. Here, this high-speed durability test is a test to start the running of each tire from a speed of 100 km / h, and increase the speed one after another in steps of 10 km / h every 5 minutes to obtain the speed at the time of failure occurrence. is there. As a result, the conventional tire 1 failed at 280 km / h, but the actual tire 1 failed at 290 km / h and the actual tire 2 up to 330 km / h, and high-speed durability was proved.

  The present invention can be applied to the industrial field of pneumatic tires.

It is meridian sectional drawing which shows Embodiment 1 of this invention. It is a partially broken plan view of the tread portion.

Explanation of symbols

11 ... Pneumatic tire 12 ... Bead core
18 ... Carcass layer 23 ... Belt layer
24, 25 ... Belt ply 26, 27 ... Belt cord
30 ... Reinforcing layer 33 ... Reinforcing cord
42 ... Belt reinforcement layer 44 ... Steel cord
46 ... Tread L ... Distance S ... Tire equator

Claims (7)

    A carcass layer extending in a toroidal manner between the pair of bead cores, a belt layer disposed outside the carcass layer in a radial direction and inclined with respect to the tire equator S, and a radius of the belt layer In a pneumatic tire provided with a tread disposed on the outer side in the direction, a pair of reinforcing layers disposed so as to overlap both ends in the width direction of the belt layer, and a reinforcing cord made of organic fiber embedded therein, a belt layer, A belt reinforcing layer provided between the tread and extending from at least one reinforcing layer to the other reinforcing layer and having a steel cord embedded therein and extending substantially parallel to the tire equator S is provided. And pneumatic tires.     The pneumatic tire according to claim 1, wherein the reinforcing layer is folded to form a hold structure that wraps both ends of the belt layer in the width direction by the reinforcing layer.     The pneumatic tire according to claim 1 or 2, wherein the reinforcing cord is made of an aromatic polyamide.     The pneumatic tire according to claim 2, wherein the reinforcing layer and both end portions in the width direction of the belt reinforcing layer are overlapped in the radial direction.     The pneumatic tire according to claim 4, wherein a distance L in a width direction in an overlapping region between the reinforcing layer and the belt reinforcing layer is in a range of 3 to 30 mm.     The pneumatic tire according to claim 4 or 5, wherein a belt reinforcing layer is disposed radially outside the reinforcing layer in an overlapping region between the reinforcing layer and the belt reinforcing layer.     The pneumatic tire according to any one of claims 1 to 6, wherein an inclination angle of the reinforcing cord embedded in the reinforcing layer with respect to the tire equator S is 30 degrees or less.

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