JP5039326B2 - Safety tire - Google Patents

Description

  The present invention has a toroidal shape over each part of a pair of bead portions in which a bead core and a bead filler are embedded, a pair of sidewall portions extending outward from the bead portion in the tire radial direction, and a tread portion extending between both sidewall portions. The present invention relates to a safety tire including a carcass formed of at least one ply extending, and at least one belt layer that is positioned on the outer peripheral side of the crown portion of the carcass and is formed by covering a cord with rubber.

  In a pneumatic tire, for example, a passenger car tire, gas is contained in the tire under a pressure of about 150 kPa to 250 kPa as a gauge pressure, and a tension is generated in a tire skeleton such as a carcass and a belt of the tire. The tire can be deformed and restored in response to the input to the tire. That is, by maintaining the tire's internal pressure within a predetermined range, a constant tension is generated in the tire skeleton, and a load supporting function is imparted and rigidity is increased, such as driving, braking and turning performance, The basic performance necessary for running the vehicle is given.

  By the way, when a tire held at a predetermined internal pressure is damaged, a tire frame portion is formed because a high-pressure gas leaks to the outside through the injury and the internal pressure of the tire decreases to atmospheric pressure. Most of the tension generated at the time is lost, the sidewall portion bulges and the bead portion collapses and deforms. As a result of the loss of the load support function and the driving, braking and turning performance obtained by applying a predetermined internal pressure to the tire, the vehicle equipped with the tire will be unable to travel.

  Therefore, many proposals have been made on tires that can run even in a puncture state, so-called safety tires. For example, one having a double wall structure, one having a load support device such as an air bladder in the tire, a tire air chamber partitioned by the tire and the rim, and a continuous phase made of a resin capable of thermal expansion Known are those in which a large number of hollow particles composed of closed cells are arranged to recover the internal pressure of the tire chamber by increasing the volume of the hollow particles during puncture. As a safety tire for passenger cars with relatively light weight, a reinforcing rubber layer with a crescent cross section is provided on the sidewall to support the tire load with the internal pressure when the internal pressure is normal. There is a known safety tire that supports a tire load with a reinforcing rubber layer instead of a shoulder, a so-called side-reinforced safety tire (see, for example, Patent Document 1). The side-reinforced safety tire has a relatively simple structure as compared to the safety tire described above, and does not require the collection of a load support device or hollow particles disposed in the tire when repairing a puncture or discarding the tire. This is advantageous.

  However, in the conventional side-reinforced safety tire, the load is supported when the air pressure is lowered only by the compression rigidity of the rubber, so that the necessary reinforcing rubber layer is inevitably increased. There has been a problem that the mass of is greatly increased. In order to suppress such an increase in mass, for example, Patent Document 2 discloses that a rubber reinforcing layer having a crescent-shaped cross section and a rubber-filament fiber composite are arranged on the inner surface of the carcass layer in the side wall, so A tire is described that achieves weight reduction by reducing the amount of rubber reinforcing layer used without impairing various performances during running.

Japanese Patent Laid-Open No. 2005-161964 JP-A-11-129712

  However, even in the safety tire described in Patent Document 2, if the reinforcing rubber layer is made too small, deformation concentrates in the vicinity of the buttress area of the tire, resulting in compression input to the carcass, the rubber reinforcing layer, and the rubber-filament fiber composite. May become the starting point of failure occurrence. In addition, the rigidity of the sidewall portion is too low, and the steering stability during run-flat running may be impaired. As described above, the safety tire described in Patent Document 2 still requires a reinforced rubber layer of a certain size, and there has been a certain limit to its weight reduction.

  The object of the present invention is to solve such problems of the prior art, and the object is to optimize the load support structure, thereby reducing the weight and stabilizing the operation during run-flat travel. The object is to provide a safety tire that achieves a high level of improvement in safety.

In order to achieve the above object, the first aspect of the present invention spans a pair of bead portions in which a bead core and a bead filler are embedded, a pair of sidewall portions extending outward in the tire radial direction from the bead portion, and both sidewall portions. In a safety tire comprising a carcass made of at least one ply extending in a toroidal shape over each part of the extending tread part, and at least one belt layer located on the outer peripheral side of the crown part of the carcass and having a cord covered with rubber, In the cross section in the tire width direction, the outer surface of the carcass is covered with a metal cord, and at least the tire diameter passes through the buttress area from the width end of the belt layer and exceeds the outer end in the tire radial direction of the bead filler. A pair of left and right reinforcing layers extending inward in the direction, the cords constituting them intersect each other across the tire circumferential direction, One, the angle of the cords and the tire circumferential direction to constitute a reinforcing layer is arranged to be within a range of less than than 80 ° 90 °, in a state filled with the internal pressure of the mounted on a standard rim specified, the bead filler The tire radial direction distance between the tire radial direction outer end portion and the rim diameter line is 200% or less of the flange height of the standard rim.

In addition, the second invention includes a pair of bead portions in which a bead core and a bead filler are embedded, a pair of sidewall portions extending outward in the tire radial direction from the bead portion, and a tread portion extending between both sidewall portions. In a safety tire comprising a carcass made of at least one ply extending in a toroidal shape and at least one belt layer formed on a crown of the carcass and coated with rubber, a cross section in the tire width direction The outer surface of the carcass is covered with a metal cord with rubber, and at least a pair of left and right reinforcing layers extending beyond the buttress area from the width end of the belt layer, the cords constituting them sandwich the tire circumferential direction. Crossing each other and the angle formed by the cord constituting the reinforcing layer and the tire circumferential direction is within a range of 80 ° or more and less than 90 ° In the state where the reinforcing layer is mounted on a standard rim and filled with a specified internal pressure, the inner end portion in the tire radial direction of the reinforcing layer is positioned on the outer side in the tire radial direction from the outer end portion in the tire radial direction of the bead filler. And a tire radial distance between a tire radial inner end of the reinforcing layer and a tire radial outer end of the bead filler is 20% or less of a tire cross-section height. It is.

  In the tire adopting the configuration of the first invention or the second invention, since a wide range of the sidewall portion can be deformed, local concentration of deformation in the run flat state can be effectively prevented.

  The “width end portion of the belt layer” here refers to the outermost end of the belt layer when the belt layer is one layer, and the widest belt layer when the belt layer is a plurality of layers. Part. “Standard rim” and “specified pressure” are industrial tires that are effective in areas where tires are manufactured, sold, or used, such as JATMA, TRA, ETRTO, etc. The standard rim (or “Approved Rim”, “Recommended Rim”) at the applicable size specified in the standards, standards, etc., and the air pressure according to the maximum load capacity of the tire, "Means the position where the rim diameter is measured.

  In the safety tires of the first and second inventions, the bead filler is preferably made of rubber having a Young's modulus of less than 14.7 kPa.

  Further, it is preferable that the reinforcing layer is positioned on the inner side in the tire radial direction with respect to the rim line in a state where the reinforcing layer is mounted on the standard rim and filled with the prescribed internal pressure. The “rim line” here is 30 mm from the outermost end in the tire radial direction of the rim flange to the outer side in the tire radial direction in a no-load state in which a tire is assembled to a standard rim and air pressure corresponding to the maximum load capacity is applied. It shall refer to the separated part.

  Furthermore, the safety tire according to the present invention preferably further includes an auxiliary belt layer that is located on the outer side in the tire radial direction of the belt layer, is formed by rubber coating the metal cord, and the metal cord extends across the tire circumferential direction. The angle formed by the cord constituting the auxiliary belt layer and the tire circumferential direction is more preferably in the range of 40 ° to 90 °.

  In addition, the safety tire of the present invention preferably further includes an auxiliary rubber layer between the carcass and the reinforcing layer.

  According to this invention, instead of a reinforcing rubber layer having a crescent-shaped cross section, a relatively lightweight metal cord rubber covering is used to reinforce the buttress area that is most easily bent, and the sidewall portion is in a run-flat state. By expanding the deformable region, it is possible to provide a safety tire that achieves a high level of weight reduction and improved steering stability during run-flat travel.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view in the width direction of a typical safety tire (hereinafter simply referred to as “tire”) according to the first invention, and shows a state in which it is mounted on a standard rim R. FIG. 2 is a cross-sectional view in the width direction of a typical tire according to the second invention, and is shown in a state where it is mounted on a standard rim R as in FIG.

  1 and 2 A tire 1 includes a pair of bead portions 4 (only one bead portion is shown in the figure) in which a bead core 2 and a bead filler 3 are embedded, and a pair of bead portions 4 extending outward in the tire radial direction. A side wall portion 5 (only one side wall portion is shown in the figure) and a tread portion 6 extending between both side wall portions are formed. Further, the tire 1 includes a carcass 7 including at least one ply (in FIG. 1 and FIG. 2, one ply) extending in a toroid shape over each part of the bead part 4, the sidewall part 5, and the tread part 6. The belt layer 8 has at least one layer (two layers in FIGS. 1 and 2) which is located on the outer peripheral side of the crown portion of the carcass 7 and is formed by rubber-covering the cord.

The main feature of the structure of the tire of the first invention shown in FIG. 1 is that the outer surface of the carcass 7 is coated with rubber on the outer surface of the carcass 7 in the tire width direction cross section. As shown in FIG. 3, the pair of left and right reinforcing layers 12 extending from the portion 9 through the buttress area 10 and beyond the tire radial direction outer end portion 11 of the bead filler 3 to the inner side in the tire radial direction, Disposing the tire 1 so as to intersect with each other across the tire circumferential direction C and an angle formed by the cord constituting the reinforcing layer and the tire circumferential direction is in a range of 80 ° or more and less than 90 ° ; The tire radial distance h1 between the tire radial outer end 11 of the bead filler 3 and the rim diameter line RL is 200% of the height h2 of the rim flange RF. Must be It is in.

The main feature of the structure of the tire according to the second invention shown in FIG. 2 is that the outer surface of the carcass 7 is covered with a metal cord on the outer surface of the carcass 7 in the tire width direction cross section. a pair of left and right reinforcing layer 12 from the part 9 extends beyond the buttress areas 10, code that constitutes them, as shown in FIG. 3, intersect each other across the tire circumferential direction C, and, forming the reinforcing layer The tire of the reinforcing layer 12 in a state where the angle formed by the cord to be tired and the tire circumferential direction is within a range of 80 ° or more and less than 90 ° , and the tire 1 is mounted on the standard rim R and filled with the specified internal pressure The radially inner end 14 is located on the outer side in the tire radial direction of the bead filler 3 with respect to the tire radial direction outer end 11, and the tire radial direction inner end 14 of the reinforcing layer 12 and the tire radial outer end of the bead filler 3. Tire diameter between 11 The orientation distance d is 20% or less of the tire cross-section height SH.

Hereinafter, how the present invention has adopted the above configuration will be described together with the operation.
The inventors examined how the destruction of the tire proceeds when a normal radial tire is punctured, and found that the progress of cracks from the width end of the belt layer and the buttress area were large. It was found that the case destruction due to bending deformation is a major factor. Cracks from the width end of the belt layer are caused by a large difference in rigidity between the portion where the belt layer is disposed and the portion where the belt layer is not disposed. Particularly, the cord constituting the belt layer is a steel cord. Yes, it occurs remarkably when the cut end of the cord is exposed. Further, the buttress region is not provided with a reinforcing member such as a belt layer or a bead filler, and the case thickness is thin, so that the structural rigidity is significantly smaller than other portions and the substrate is easily bent. Therefore, the inventors have at least overlapped with the width end portion 9 of the belt layer 8 as shown in FIGS. 1 and 2 in a range exceeding the buttress area 10 from the width end portion 9 of the belt layer 8. By disposing the reinforcing layer 12 in the above, if the rigidity step at the width end portion 9 of the belt layer 8 is eliminated and the structural rigidity of the buttress region 10 is improved, the tire breakage as described above can be prevented. I got the idea.

  However, simply disposing the reinforcing layer in the above range could not effectively prevent tire destruction even though the occurrence of cracks from the width end portion of the belt layer could be suppressed. The inventors have further studied the tire destruction, and have found that the tire destruction occurs when the cords constituting the left and right reinforcing layers are inclined in the same direction with respect to the tire circumferential direction. This reason will be further described with reference to FIG. In FIG. 11, the cords constituting both the left and right reinforcing layers are inclined in the same direction with respect to the tire circumferential direction, that is, the second coordinate plane having the tire circumferential direction as the y axis and the tire width direction as the x axis. A cord extends into the quadrant and the fourth quadrant. When a tire having such a cord configuration is grounded in order from the lower side of FIG. 11, in the left half region, the cord of the reinforcing layer receives a load first from the end located on the tread portion side and bears this load. Since it acts as a beam, the deformation of the tire is small, on the contrary, in the right half area, the cord of the reinforcement layer receives the load from the end located on the bead part side first, so it does not bear the load, Compared to the left half, tire deformation is large. For this reason, as a result of the generation of a lateral force from the left half region to the right half region, the deformation of the buttress region in the right half region becomes increasingly larger, and the destruction of the tire is promoted. Therefore, the inventors, as shown in FIG. 3, lay the left and right reinforcing layers so that the cords constituting them are opposite to each other in the tire circumferential direction, that is, cross each other across the tire circumferential direction. By arranging and maintaining the deformations of the left and right halves of the tire at the same level, it was conceived that in addition to eliminating the rigidity step in the buttress area and improving the structural rigidity, the occurrence of such lateral force was prevented. As a result, the structure can be simplified and the weight can be significantly reduced as compared with the case of using a conventional reinforcing rubber having a crescent-shaped cross section.

Further, in general tires, by increasing the bead filler or by using hard rubber, the rigidity of the bead portion and the sidewall portion is increased and the deformation of the tire is suppressed. If the configuration is used as it is for side-reinforced safety tires, the buttress area is likely to fail during run-flat driving. This is because the deformation of the sidewall portion is suppressed by the bead filler, so that the region that can be deformed when the internal pressure of the tire is reduced is reduced, and the structural rigidity is locally different, particularly as shown in FIG. This is because deformation concentrates in a lower buttress area compared to the part. Therefore, the inventors widen the deformable region of the sidewall portion 5, specifically, the tire radial direction distance h ₁ between the tire radial direction outer end portion 11 of the bead filler 3 and the rim diameter line RL. , completed a 200% or less of the rim flange RF of the height h _2, by relatively low with respect to the side wall portion 5 overall height, found to be able to avoid the concentration of the local deformation, the first invention did. In such a tire, as shown in FIG. 4, since the entire sidewall portion 5 is deformed, the occurrence of failure is reduced.

The distance h ₁ can be reduced within a range that does not impair the effect of reinforcing the bead portion 4 in the normal internal pressure state, and a more preferable range is less than 100% of the height h ₂ . The portion of the tire 1 that is in contact with the rim flange RF is prevented from being deformed by the rim flange RF, but the portion that is on the outer side in the tire radial direction can be deformed. Therefore, by setting the distance h ₁ to be less than 100% of the height h ₂ , that is, by making the height of the bead filler 3 lower than the height of the rim flange RF, the deformable region of the sidewall portion 5 is maximized. And local concentration of deformation can be effectively avoided.

Further, the inventors improve the structural rigidity of the buttress region 10 by the reinforcing layer 12 and provide the sidewall portion 5 with a portion having a low structural rigidity and easily deforming, specifically, the inner side of the reinforcing layer 12 in the tire radial direction. The end portion 14 is positioned on the outer side in the tire radial direction of the bead filler 3 in the tire radial direction so that the reinforcing layer 12 and the bead filler 3 do not overlap with each other. The idea that local concentration of deformation in the buttress area can be avoided by making it easy to deform the outer end 11 in the tire radial direction of the portion 14 and the bead filler 3 is obtained. However, if the reinforcing layer 12 and the bead filler 3 overlap as in the first invention, the rigidity step at the inner end 14 in the tire radial direction of the reinforcing layer 12 will not be a problem, but it does not overlap. Therefore, deformation concentrates on the inner end 14 of the reinforcing layer 12 in the tire radial direction, and there is a possibility that a crack may occur or the carcass ply may be cut. Therefore, the inventors have further researched on the appropriate range of the arrangement position of the inner end portion 14 in the tire radial direction of the reinforcing layer 12, and the outer end portion in the tire radial direction of the tire radial inner end portion 14 of the reinforcing layer 12 and the bead filler 3. If the distance d in the tire radial direction from the end 11 is 20% or less of the tire cross-section height SH, concentration of deformation on the inner end 14 in the tire radial direction of the reinforcing layer 12 can be prevented, and cracks and carcass plies can be prevented. As a result, the second invention was completed. Also in the second invention, it is preferable to widen the deformable region of the sidewall portion 5 as in the first invention, and specifically, between the tire radial direction outer end portion 11 of the bead filler 3 and the rim diameter line RL. It is possible to avoid local concentration of deformation by making the tire radial direction distance h ₁ relatively lower than the height h ₂ of the rim flange RF and not more than 200% of the overall height of the sidewall portion 5. To preferred.

  Even if the rubber constituting the bead filler 3 is softened, the sidewall portion 5 is easily deformed. Specifically, if a rubber having a Young's modulus of less than 14.7 kPa is used, the entire sidewall portion 5 can be deformed in a run-flat state, and local concentration of deformation can be effectively avoided. ,preferable. The Young's modulus of the rubber constituting the bead filler 3 can be appropriately reduced as long as the effect of reinforcing the bead portion 4 in a normal internal pressure state is not impaired.

  Furthermore, during run-flat running, the maximum width position 13 of the tire 1 (which is the position at which the cross-sectional width of the tire is measured) is followed by the buttress area 10 where the deformation is maximum, and the pattern, characters or rim guard on the outer surface of the tire. If there is a portion, etc., a failure is likely to occur at a position where the cross-sectional width of the tire excluding these is measured. The reason is as follows. A driving force transmitted to the bead portion 4 via the rim R and a resistance force acting in a direction opposite to the driving force of the tire wheel is generated on the traveling tire wheel due to friction between the tread portion 6 and the road surface. . As a result, a difference in rotational angular velocity occurs between the bead portion 4 fixed to the rim R and the tread portion 6 that contacts the road surface, and torsional deformation occurs in the sidewall portion 5. In side-reinforced run-flat tires, when running flat, the ply cord does not have sufficient tension, and the tire load is supported only by the inherent rigidity of the reinforced sidewall portion 5. The torsional deformation of the sidewall portion 5 is large, and this torsional deformation becomes maximum at the tire maximum width position 13. Therefore, the reinforcing layer 12 is disposed in a range beyond the tire maximum width position 13 from the width end portion 9 of the belt layer 8, thereby further increasing the rigidity of the sidewall portion 5 and torsional deformation at the tire maximum width position 13. It is preferable from the viewpoint of improving run flat durability. In this case, since sufficient tension is not applied to the ply cord, the inner end portion 14 in the tire radial direction of the reinforcing layer 12 becomes a free end, which may become a core of failure occurrence. Therefore, it is more preferable that the inner end portion 14 is disposed on the inner side in the tire radial direction with respect to the rim line with little bending deformation, and the tire radial direction inner end portion 14 is substantially fixed.

  Moreover, you may provide the rim guard part 15 which protrudes on the outer surface of the tire 1 and the tire width direction outer side rather than the flange RF of the standard rim R to which the tire is mounted. When such a rim guard part 15 is provided, the bending rigidity of the bead part 4 is remarkably increased, the deflection and deformation amount of the sidewall part 5 during the run-flat running are effectively suppressed, and tire failure is less likely to occur. In this case, since there is little bending deformation in the range where the rim guard part 15 is provided, the inner end 14 in the tire radial direction of the reinforcing layer 12 passes through the outer end 16 in the tire radial direction of the rim guard 15 and is orthogonal to the inner surface of the tire. If it is on the inner side in the tire radial direction than the straight line N, the inner end portion 14 in the tire radial direction of the reinforcing layer 11 can be substantially fixed, and the occurrence of failure from here can be suppressed.

  In particular, when the load applied to the tire is large, when the tire rolls, the reinforcing layer 12 is arranged so that the cords constituting the left and right reinforcing layers 12 receive the load first from the end located on the tread portion 6 side. It is preferable to arrange the reinforcing layer 12 so that the cords constituting both the reinforcing layers are formed in a C shape when viewed from the tire rotation direction. With such an arrangement, as described above, the reinforcing layer 12 acts as a beam, so that the deformation of the tire can be further suppressed, and it contributes further to the improvement of the run-flat durability.

  Further, when the metal cords constituting the reinforcing layer 12 are arranged close to the tire circumferential direction C, that is, when the angle α formed by the metal cords constituting the reinforcing layer 12 and the tire circumferential direction C is reduced, the reinforcing layer 12 is arranged. As a result, the occurrence of flexural deformation in the buttress area 10 can be suppressed, and the load applied to the cord can be reduced. However, as the angle α decreases, the reinforcement layer 12 is deformed in the direction of twisting the cord constituting the buttress area 10 when it is bent, so that the possibility of the cord being cut increases. And if the former is compared with the latter, the influence of the latter is very large. Based on these findings, the inventors have intensively studied the appropriate range of the angle α formed by the metal cord constituting the reinforcing layer 12 and the tire circumferential direction C, and found that it is advantageous to increase the angle α. Specifically, if the angle α is in the range of 80 ° or more and less than 90 °, the occurrence of bending deformation of the buttress region 10 can be suppressed without worrying about the cord being cut, and the run-flat durability can be improved. It was found that it is advantageous for improvement. A more preferable range of the angle α is 85 ° or more and less than 90 °. The configuration of the metal cord is not particularly limited, but a filament with a relatively small diameter is used from the viewpoint of reducing deformation strain and improving run-flat durability even when a large bending input occurs during run-flat running. In particular, it is preferable to use fine filaments having a diameter of 0.3 mm or less.

  Furthermore, it is known that when the air pressure decreases, the tread portion 6 deforms in a concave shape with respect to the road surface, so-called buckling deformation occurs. Even when buckling deformation is large, the amount of bending of the buttress area 10 increases, so the number of layers of the belt layer 8 is increased, or a cap layer 17 made of organic fiber cord or the like is disposed on the outer peripheral side of the belt layer 8. In view of maintaining run-flat durability, it is preferable to reinforce the rigidity of the tread portion 6 and suppress buckling deformation. In particular, the auxiliary belt layer 18 formed by rubber-coating a metal cord having high compression rigidity and having an angle β between the metal cord and the tire circumferential direction C in the range of 40 ° or more and 90 ° or less is used for the tire of the belt layer 8. It is advantageous to arrange them radially outward. A more preferable range of the angle β is 80 ° or more and 90 ° or less, and the effect of suppressing buckling deformation is highest when the angle β is 90 °.

  The cords constituting the reinforcing layer 12 and the auxiliary belt layer 18 are made of metal cords, because these layers act as a beam to suppress deformation of the tire when the tire internal pressure is reduced, so that the compression resistance is low. Because it is required. A preferred metal cord is a steel cord from the viewpoint of cost and resistance to fretting.

  Although not shown, in a tire in which a tread portion is provided with a circumferential groove extending in the tire circumferential direction, local deformation occurs around the circumferential groove, and the entire tread portion 6 may be buckled greatly. Are known. In order to suppress such buckling, the width end portion of the auxiliary belt layer 18 is arranged on the outer side in the tire width direction of the circumferential groove, that is, the auxiliary belt layer 18 passes from the tire equatorial plane directly under the circumferential groove, Furthermore, it is preferable to extend the tire width direction outside. As a result, the rigidity of the portion where the circumferential groove is disposed can be reinforced, and local deformation of the tread portion 6 around the circumferential groove, and hence buckling can be effectively suppressed.

  When buckling occurs, a compressive force acts on the auxiliary belt layer 18 in the tire width direction. Therefore, in order to more effectively suppress buckling, it is preferable to increase the compressive force in the tire width direction of the auxiliary belt layer 18. Specifically, the angle β formed by the cord constituting the auxiliary belt layer 18 and the tire circumferential direction is preferably relatively large, more preferably 40 ° or more and 90 ° or less, and 60 ° or more and 90 ° or less. More preferably, it is 90 °. Alternatively, if the cord constituting the auxiliary belt layer 18 is a filament having a relatively large diameter, preferably a filament having a diameter of 0.6 mm or more, even if the same amount of material is used, the filament is relatively thick. Therefore, the buckling can be effectively suppressed while suppressing an increase in mass. Of course, if the cord using the filament having a relatively large diameter is arranged so that the angle formed with the tire circumferential direction is relatively large, the compression rigidity of the auxiliary belt layer in the tire width direction is further improved.

  From the viewpoint of reducing the rigidity step at the width end of the belt layer 8, the belt layer 8 and the reinforcing layer 12 are preferably disposed so as to overlap each other by 3 mm or more, and disposed so as to overlap each other by 5 mm or more. More preferably. However, when the overlap amount exceeds 20 mm, there is almost no change in the effect of reducing the rigidity step, but since the mass of the tire 1 increases as the reinforcing layer 12 increases, the overlap amount is set to 20 mm or less. It is preferable to do.

  Further, as shown in FIG. 5, an auxiliary rubber layer 19 may be provided between the carcass 7 and the reinforcing layer 12. When such a configuration is adopted, since rubber is generally resistant to compression, the auxiliary rubber layer 19 also applies a load, and the load applied to the reinforcing layer 12 is reduced. Therefore, the life of the metal cord of the reinforcing layer 12 is extended, the number of cords of the reinforcing layer 12 driven in can be reduced, and the weight of the reinforcing layer 12 can be reduced. In addition, when the auxiliary rubber layer 19 is provided in this way, the reinforcing layer 12 can be arranged on the tire outer surface side more than when the auxiliary rubber layer 19 is not provided. When the tire is bent and deformed, a tensile force acts on the outer surface side of the tire. However, since the metal cord is excellent in tensile resistance, the buttress of the tire 1 can be more effectively disposed by arranging it on the outer surface side. The deformation of the area 10 can be suppressed. In particular, when at least a part of the reinforcing layer 12 is located on the outer surface side of the thickness center line TC of the tire 1 in the region where the auxiliary rubber layer 19 is disposed, the effect of suppressing deformation becomes large.

  Note that the above description shows only a part of the embodiment of the present invention, and these configurations can be combined with each other or various modifications can be made without departing from the gist of the present invention. . For example, FIG. 1 shows a mode in which the end of the reinforcement layer 12 on the bead side is sandwiched between the main body portion and the folded portion of the carcass 7, but as shown in FIG. It is good also as arrangement | positioning which covers an outer surface. Further, as shown in FIGS. 7 to 9, the auxiliary reinforcing layer 20 can be disposed on the inner surface or the outer surface of the reinforcing layer 12 in a portion where the tire 1 is particularly likely to bend and deform. This is because the auxiliary reinforcing layer 20 can more effectively suppress the bending deformation of the tire 1. The auxiliary reinforcing layer 20 is preferably configured similarly to the reinforcing layer 12. Further, the angle β formed by the metal cord constituting the reinforcing layer 12 and the tire circumferential direction C may be the same in the left and right half regions as shown in FIG. 2, but as shown in FIG. May be different.

  Next, tires according to the present invention were prototyped and performance evaluations were performed, which will be described below.

The tires of Examples 1 to 9 and Comparative Examples 3 and 4 are radial tires for passenger cars having a tire size of 205 / 55R16, have a reinforcing layer formed by rubber-coating a steel cord, and have the specifications shown in Table 1. Have. The angle formed by the cord constituting the reinforcing layer and the tire circumferential direction is the same in each of the left and right half regions, 85 ° in Examples 1 to 7 and 9 , 80 ° in Example 8, 75 ° in Comparative Example 3 , and comparison. In Example 4 , it is 70 °. The tires of Examples 1, 2, 4 to 6 , 8 and Comparative Examples 3 and 4 have the structure shown in FIG. 1, and the tire of Example 3 does not have an auxiliary belt layer. The tire of Example 7 has a structure as shown in FIG. 5, and the tire of Example 9 has a structure as shown in FIG. ing. Further, in the tires of Examples 1 , 2 , 4 to 9, and Comparative Examples 3 and 4 , the cords constituting the auxiliary belt layer are steel cords. Moreover, the tire of Example 7 has an auxiliary rubber layer, and in the arrangement region, a part of the reinforcing layer is located on the outer surface side of the tire thickness center line.

For comparison, the tire size is the same as the tires of Examples 1 to 9 , the tire of Conventional Example 1 having a crescent-shaped reinforcing rubber layer, and the tire size is the same as the tires of Examples 1 to 9 , and the reinforcement The tire of Conventional Example 2 having no structure, the tire size is the same as the tires of Examples 1 to 9 and has the structure shown in FIG. 1, but the cord constituting the reinforcing layer is an organic fiber cord The tire formed in Comparative Example 1 has an angle between the cord and the tire circumferential direction of 85 °, the tire size is the same as that of the tires of Examples 1 to 9 , and the cord constituting the reinforcing layer is a steel cord. The tire of Comparative Example 2 in which the angle formed by the tire circumferential direction is 85 °, but the reinforcing layer does not form an overlap with the bead filler, was also prototyped.

  The mass of each test tire was measured. The measurement results are shown in Table 1. Further, each test tire is mounted on a rim of size 7J × 16 to be a tire wheel, is attached to a test vehicle, is applied with a tire load of 3.92 kN, and has an internal pressure of 0 kPa (relative pressure) and 80 km. The test course was run at a speed of / h, the running time until the tire was destroyed was measured, and the run-flat durability was evaluated based on the running time. The evaluation results are shown in Table 1.

  Each of the test tires was mounted on a rim of size 7J × 16 to form a tire wheel, and the internal pressure was 230 kPa (relative pressure). Then, a tire load of 3.92 kN was applied, the force when the tire rim center was moved 1 mm in the front-rear direction and the lateral direction was measured, and the longitudinal rigidity and lateral rigidity were evaluated from these values, respectively. The evaluation results are shown in Table 1.

  The height of the bead filler in Table 1 is an index ratio when the rim flange height of the standard rim is 100%. Moreover, the evaluation result of mass is shown by the index ratio when the mass of the tire of Conventional Example 1 is 100, and the smaller the value, the lighter the weight. The run-flat durability evaluation results are A for running time of 60 minutes or more, B for 45 minutes to less than 60 minutes, C for 30 minutes to less than 45 minutes, and 15 minutes to less than 30 minutes. , D and less than 15 minutes are shown as E, with A being the best and E being the worst. The longitudinal rigidity and lateral rigidity are shown as index ratios when the rigidity of the tire of Conventional Example 2 is set to 100, and the larger the numerical value, the higher the rigidity.

From the results shown in Table 1, the tires of Examples 1 to 9 are slightly inferior in run-flat durability, front-rear rigidity and lateral rigidity as compared with the tire of Conventional Example 1, but are sufficiently within the practical range. It can be seen that significant weight reduction has been achieved. Moreover, although the tires of Conventional Example 2 and Comparative Example 1 are extremely lightweight, run flat running is impossible, and compared with these tires, although the tires of Examples 1 to 9 are slightly larger in mass, While it is sufficiently lightweight as a safety tire, it has excellent run-flat durability, longitudinal rigidity and lateral rigidity. Moreover, compared with the tire of Comparative Example 2, the tires of Examples 1 to 9 have improved front and rear rigidity and lateral rigidity while maintaining the same mass and run-flat durability, and are excellent in handling stability. It can be said that. Therefore, it can be seen that the tires of Examples 1 to 9 are superior in overall performance as compared with the tires of Conventional Examples 1 and 2 and the tires of Comparative Examples 1 and 2.

  According to the present invention, by optimizing the load support structure, it has become possible to provide a safety tire that achieves both a reduction in weight and an improvement in steering stability during run-flat travel at a high level.

FIG. 2 is a left half sectional view in the width direction of a typical safety tire according to the first invention, and schematically shows a state where it is mounted on a standard rim. It is the left half sectional view of the width direction of the typical safety tire according to the 2nd invention, and shows the state where it was equipped with the standard rim. 1 is a schematic development view showing a cord arrangement of a belt layer, a reinforcing layer, and a carcass of a typical safety tire according to the present invention. FIG. 3 is a cross-sectional view in the width direction schematically showing a state in which the internal pressure of a typical safety tire according to the present invention is reduced. FIG. 6 is a left half sectional view in the width direction of another safety tire according to the present invention, schematically showing a state in which the safety tire is mounted on a standard rim. FIG. 6 is a left half sectional view in the width direction of another safety tire according to the present invention, schematically showing a state in which the safety tire is mounted on a standard rim. FIG. 6 is a left half sectional view in the width direction of another safety tire according to the present invention, schematically showing a state in which the safety tire is mounted on a standard rim. FIG. 6 is a left half sectional view in the width direction of another safety tire according to the present invention, schematically showing a state in which the safety tire is mounted on a standard rim. FIG. 6 is a left half sectional view in the width direction of another safety tire according to the present invention, schematically showing a state in which the safety tire is mounted on a standard rim. It is an expanded view which shows the cord arrangement | sequence of the belt layer of another safety tire according to this invention, a reinforcement layer, and a carcass. It is an expanded view which shows the cord arrangement | sequence of the belt layer of a conventional safety tire, a reinforcement layer, and a carcass. FIG. 3 is a cross-sectional view in the width direction schematically showing a state in which the internal pressure of the safety tire is reduced, where the height of the bead filler is outside the scope of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 2 Bead core 3 Bead filler 4 Bead part 5 Side wall part 6 Tread part 7 Carcass 8 Belt layer 9 Width edge part of belt layer 10 Buttress area 11 Tire radial direction outer edge part 12 Reinforcement layer 13 Tire maximum width position 14 Reinforcement layer inner end portion in tire radial direction 15 Rim guard portion 16 Outer end portion in tire radial direction of rim guard portion 17 Cap layer 18 Auxiliary belt layer 19 Auxiliary rubber layer 20 Auxiliary reinforcement layer R rim RF rim flange RL Rim diameter line C Tire circumference direction

Claims (7)

At least one sheet extending in a toroidal shape across a pair of bead portions in which a bead core and a bead filler are embedded, a pair of sidewall portions extending outward in the tire radial direction from the bead portion, and a tread portion extending between both sidewall portions. In a safety tire comprising a carcass made of a ply of the above and at least one belt layer formed on the outer periphery of the crown portion of the carcass and covered with a rubber cord,
In the cross section in the tire width direction, the outer surface of the carcass is covered with a metal cord, and at least the tire diameter passes through the buttress area from the width end of the belt layer and exceeds the outer end in the tire radial direction of the bead filler. A pair of left and right reinforcing layers extending inward in the direction, and cords constituting them intersect each other across the tire circumferential direction, and an angle formed by the cord constituting the reinforcing layer and the tire circumferential direction is 80 ° or more and less than 90 ° To be within the range of
When mounted on a standard rim and filled with a specified internal pressure, the tire radial distance between the outer end of the bead filler in the tire radial direction and the rim diameter line is 200% or less of the flange height of the standard rim. A safety tire characterized by being. At least one sheet extending in a toroidal shape across a pair of bead portions in which a bead core and a bead filler are embedded, a pair of sidewall portions extending outward in the tire radial direction from the bead portion, and a tread portion extending between both sidewall portions. In a safety tire comprising a carcass made of a ply of the above and at least one belt layer formed on the outer periphery of the crown portion of the carcass and covered with a rubber cord,
In the tire width direction cross-section, a metal cord is covered with rubber on the outer surface of the carcass, and at least a pair of left and right reinforcing layers extending beyond the buttress area from the width end portion of the belt layer are cords constituting them. Crossing each other across the tire circumferential direction, and arranged so that the angle formed by the cord constituting the reinforcing layer and the tire circumferential direction is in the range of 80 ° or more and less than 90 ° ,
In a state where the tire is mounted on a standard rim and filled with a specified internal pressure, the inner end portion in the tire radial direction of the reinforcing layer is positioned on the outer side in the tire radial direction with respect to the outer end portion in the tire radial direction of the bead filler, A safety tire, wherein a tire radial distance between a tire radial inner end and a tire radial outer end of the bead filler is 20% or less of a tire cross-section height.   The safety tire according to claim 1 or 2, wherein the bead filler is made of rubber having a Young's modulus of less than 14.7 kPa.   The tire radial direction inner side edge part of the said reinforcement layer is located in a tire radial direction inner side rather than a rim line in the state which was mounted | worn with the standard rim | limb and was filled with the predetermined | prescribed internal pressure. Safety tires. Located in the tire radial direction outside of the belt layer, a metal cord made with rubberized, further comprising an auxiliary belt layer in which the metal cord extending across the tire circumferential direction, any one of claims 1-4 Safety tires as described in The safety tire according to claim 5 , wherein an angle formed by a cord constituting the auxiliary belt layer and a tire circumferential direction is in a range of 40 ° to 90 °. The safety tire according to any one of claims 1 to 6 , further comprising an auxiliary rubber layer between the carcass and the reinforcing layer.

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