JP4944487B2 - Run-flat tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a run-flat tire that can continuously run for a relatively long distance even when punctured, and particularly relates to a tire that can improve run-flat durability while suppressing an increase in the mass of the tire.

  Conventionally, there has been known a run-flat tire that can continuously travel at a relatively high speed for a certain distance (hereinafter referred to as “run-flat travel”) even when the air from the tire is removed due to puncture or the like. ing. This type of run-flat tire is provided with a side reinforcement body having a substantially crescent cross section made of rubber in order to increase the bending rigidity of the sidewall portion. And when the air of a tire escapes, this side reinforcement body supports the load of a tire and the vertical deflection of a tire is suppressed. Therefore, in order to increase the run-flat travel distance, the side reinforcing body has been conventionally increased in size.

  However, the increase in the size of the side reinforcing body tends to deteriorate the fuel consumption performance because the mass of the tire is increased. Further, since the enlarged side reinforcement tends to generate heat easily, there is room for further improvement in terms of durability.

  Related technologies include the following:

JP 2002-301911 A Japanese Patent No. 2999489

  The present invention has been devised in view of the above problems, and the side reinforcing body disposed inside the carcass is composed of a rubber portion and a reinforcing cord layer covered with the rubber portion. The main object is to provide a run-flat tire that can improve the run-flat durability while suppressing an increase in the mass of the tire.

Of the present invention, the invention according to claim 1 is a toroidal carcass that extends from the tread portion through the sidewall portion to the bead core of the bead portion, and a side reinforcement body that is disposed inside the carcass and has a substantially crescent-shaped cross section. a run-flat tire equipped with the side reinforcing member comprises a rubber portion, viewed contains a reinforcing cord layer covered by said rubber portion, the rubber portion is ribbon-like rubber strip in the tire rotation axis The reinforcing cord layer is formed by winding a ribbon-like cord ply in which cords are arranged at right angles to the length direction in a spiral manner around the tire rotation axis. It is characterized by being formed .

The invention according to claim 2 is the run flat tire according to claim 1 , wherein each of the reinforcing cord layers is inclined outward in the tire axial direction toward the tread portion side in the tire cross section .

According to a third aspect of the present invention, the side reinforcement includes a first layer in which the rubber strip and the cord ply are wound from an outer end in a tire radial direction toward an inner end of the side reinforcement, The reinforcing cord layer provided on the first layer has a second layer around which the rubber strip and the cord ply are wound from the inner end to the outer end in the tire radial direction of the side reinforcing body. In addition, each cord is inclined outward in the tire axial direction toward the tread portion side in the tire cross section, and the reinforcing cord layer provided in the second layer is configured such that each cord is tire toward the tread portion side in the tire cross section. The cords of the reinforcing cord layers that are inclined inward in the axial direction and provided in the first layer and the second layer are arranged separately on the outer side and the inner side of the side reinforcing body in the tire radial direction, and the tire A run-flat tire according to claim 1 or 2 wherein is provided without intersecting the tire axial direction line passing through the substantial point.

  The invention according to claim 4 is the run flat tire according to claim 3, wherein the reinforcing cord layers are wound without overlapping each other.

  The invention according to claim 5 is the run flat tire according to any one of claims 1 to 4, wherein the reinforcing cord layer has a cord having an angle of ± 30 degrees with respect to a radial direction.

According to a sixth aspect of the present invention, in the tire meridian cross section including a tire rotation axis in a normal unloaded state in which a normal rim is assembled and a normal inner pressure is filled, the tire outer surface profile includes the tire outer surface. When the point on the outer surface of the tire separating the distance (SP) of 45% of the maximum tire width (SW) from the intersection (CP) between the tire and the tire equator (C) is (P), the point from the intersection (CP) The run-flat tire according to any one of claims 1 to 5, wherein the radius of curvature (RC) of the tire outer surface gradually decreases in a section up to (P) and satisfies the following relationship.
0.05 <Y60 / H ≦ 0.1
0.1 <Y75 / H ≦ 0.2
0.2 <Y90 / H ≦ 0.4
0.4 <Y100 / H ≦ 0.7
Here, Y60, Y75, Y90, and Y100 represent the tire axial distances of 60%, 75%, 90%, and 100% of the half width (SW / 2) of the maximum tire width in the tire axial direction from the intersection (CP). The distances in the tire radial direction between the points P60, P75, P90 and P100 on the tire outer surface which are separated from each other and the intersection (CP), and H is the tire cross-sectional height.

The invention according to claim 7 includes a toroidal carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a side reinforcing body disposed inside the carcass and having a substantially crescent-shaped cross section. A method for manufacturing a run-flat tire , comprising: forming a composite strip by overlapping a ribbon-like rubber strip and a ribbon-like cord ply in which cords are arranged at right angles to the length direction ; And a step of forming at least a part of the side reinforcing body by winding the composite strip spirally around the cylindrical body to be wound a plurality of times .

  In the invention according to claim 8, in the composite strip, the width of the rubber strip is larger than the width of the cord ply, and both side edges of the rubber strip protrude from both side edges of the cord ply. 7. A method for producing a run-flat tire according to item 7.

  According to a ninth aspect of the present invention, in the step of winding the composite strip, the first winding step of winding the composite strip toward one side in the axial direction of the wound body and the other in the axial direction of the wound body. The run-flat tire manufacturing method according to claim 7, further comprising a second winding step wound toward the side.

  In the run-flat tire of the present invention, the side reinforcing body that is disposed inside the carcass and has a substantially crescent-shaped cross section includes a rubber portion and a reinforcing cord layer covered with the rubber portion. The cord of the reinforcing cord layer has a specific gravity smaller than that of rubber and hardly generates heat. Therefore, such a side reinforcing body can effectively increase its bending rigidity while suppressing an increase in mass. Therefore, the run flat tire of the present invention can improve run flat durability while suppressing an increase in tire mass.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a run-flat tire 1 according to the present embodiment in a normal no-load state, FIG. 2 is an enlarged view of a main part thereof, and FIG. 1 is a cross-sectional view of a run-flat state. Unless otherwise specified, the dimensions of each part of the tire are the values in the normal no-load state.

  Here, the “regular no-load state” refers to a no-load state in which the run-flat tire 1 is assembled to the regular rim J and filled with the regular internal pressure.

  In addition, the “regular rim” is a rim determined for each tire in a standard system including a standard on which a tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, For ETRTO, use “Measuring Rim”.

  Furthermore, the “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum air pressure is JATMA and the table “TIRE LOAD” is TRA. The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 kPa for tires for passenger cars.

  Furthermore, the “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum value described in “LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” in the case of ETRTO.

  The run-flat tire 1 includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2. And a bead apex 8 extending from the outer surface of the bead core 5 in the tire radial direction to the outer side in the tire radial direction, and a substantially crescent-shaped cross section disposed on at least a part of the inside of the carcass 6 and the side wall portion 3. And an inner liner rubber 10 made of rubber having a gas barrier property disposed on the inner side in the tire axial direction of the side reinforcing body 9.

  The carcass 6 is formed of one or more carcass plies 6A in the present embodiment in which a carcass cord arranged at an angle of 70 to 90 ° with respect to the tire equator C is covered with a topping rubber. The carcass cord is preferably an organic fiber cord such as nylon, polyester, rayon or aromatic polyamide. The carcass ply 6A includes a toroidal main body portion 6a extending between the bead cores 5 and 5 and a pair of folded back portions that are provided on both sides of the bead core 5 and are folded from the inner side to the outer side in the tire axial direction. Part 6b.

  The bead apex rubber 8 is disposed between the main body portion 6a and the folded portion 6b of the carcass ply 6A. The bead apex rubber 8 is made of a relatively hard rubber, for example, having a rubber hardness of 65 to 95 degrees or more, more preferably 70 to 90 degrees, thereby increasing the bending rigidity of the bead portion 4 and thus improving the handling stability. To help.

  The height ha in the tire radial direction from the bead base line BL to the outer end 8t of the bead apex rubber 8 is not particularly limited, but if it is too small, the steering stability in the run-flat state tends to be lowered, and conversely it is too large. And there is a risk of worsening the ride comfort. From such a viewpoint, the height ha is preferably 20% or more, more preferably 25% or more of the tire cross-section height H, and the upper limit is preferably 50% or less, more preferably 45% or less. Is desirable.

  In the present embodiment, the folded portion 6b of the carcass ply 6A extends beyond the outer end 8t of the bead apex rubber 8 outward in the tire radial direction, and the outer end portion 6be is between the main body portion 6a and the belt layer 7. It is in the position between. Thereby, the side wall part 3 is effectively reinforced by the single carcass ply 6A.

  The belt layer 7 is composed of a total of two cross belt plies 7A and 7B inside and outside of the tire in which a belt cord arranged at an angle of 10 to 35 ° with respect to the tire equator C is covered with a topping rubber, for example. Is done. The width (in this example, the width between the outer ends 7e of the wide belt ply 7A) BW of the belt layer 7 is preferably 0.70 to 0.95 times the tire maximum width SW. Thereby, a tagging effect is imparted over almost the entire area of the tread portion 2, and the profile of the tire outer surface described later is maintained.

  The tire maximum width SW is a tire axial distance between the tire maximum width points M and M. Further, the tire maximum width position M is determined from the tire cross-sectional contour shape excluding characters, patterns, rim protectors and the like provided on the sidewall portion 3, and specifically, the same as the point m forming the maximum width of the carcass 6. It is at height.

  The inner liner rubber 10 is disposed in a toroid shape so as to include the inside of the side reinforcing body 9 and substantially straddle between the bead portions 4 and 4 in order to retain air in the tire lumen i. The inner liner rubber 10 is formed of a rubber composition having gas barrier properties such as butyl rubber, halogenated butyl rubber and / or brominated butyl rubber.

  The side reinforcing body 9 has a substantially crescent-shaped cross section in which the thickness is gradually reduced from the central portion toward the inner end 9i and the outer end 9o in the tire radial direction and smoothly curved along the sidewall portion 3. It has a contour.

  Further, the inner end 9 i of the side reinforcing body 9 is preferably located on the inner side in the tire radial direction than the outer end 8 t of the bead apex 8 and on the outer side in the tire radial direction than the bead core 5. Thereby, a location with low rigidity can be eliminated between the side reinforcement body 9 and the bead apex rubber 8, and the bending rigidity from the side wall part 3 to the bead part 4 can be improved with good balance. In particular, the length Wi in the tire radial direction of the overlapping portion between the side reinforcing body 9 and the bead apex rubber 8 is preferably 5 to 50 mm.

  It is desirable that the outer end 9o of the side reinforcing body 9 reaches, for example, the inside of the tread portion 2 and terminates at a position on the inner side in the tire axial direction from the outer end 7e of the belt layer 7. This is useful for effectively increasing the rigidity of the buttress portion and the like. The length Wo in the tire axial direction of the overlapping portion between the side reinforcement 9 and the belt layer 7 is preferably larger than 0 and 50 mm or less.

  The length L in the tire radial direction between the inner end 9i and the outer end 9o of the side reinforcing body 9 is not particularly limited, but if it is too small, the reinforcing effect of the sidewall portion 3 tends to be lowered, and conversely, if it is too large, There is a tendency to deteriorate the riding comfort and rim assemblability during normal driving. From such a viewpoint, the length L of the side reinforcing body 9 is preferably set to 35 to 70%, more preferably about 40 to 65% of the tire cross-section height H.

  The maximum thickness tc of the side reinforcing body 9 can be determined as appropriate according to the load applied and the tire size. However, if it is too small, it is difficult to obtain the effect of reinforcing the sidewall portion 3, and conversely, if it is too large. There is a risk of causing an increase in tire mass and excessive heat generation. From such a viewpoint, the maximum thickness tc is preferably 5 mm or more, more preferably 8 mm or more, and the upper limit is preferably 20 mm or less, more preferably 15 mm or less.

  The side reinforcing body 9 is composed of a rubber portion 9A formed of rubber and a reinforcing cord layer 9B covered with the rubber portion 9A. The side reinforcing body 9 of the present embodiment has a ribbon-like rubber strip 11 and a ribbon-like cord ply 12 as shown in FIG. 5 spirally wound around a tire rotation axis as shown in FIG. The strip laminate 9m is used. The rubber strip 11, the cord ply 12, and the strip laminated body 9m shown in FIGS. 5 and 7 are all shown in a state before vulcanization.

  Since the cord material of the reinforcing cord layer 9B usually has a lower specific gravity than rubber, the bending rigidity of the side reinforcing body 9 can be increased with a smaller mass. Further, since the cord material is less likely to generate heat than the rubber material, the heat generation of the side reinforcing body 9 during the run flat running can be suppressed. The run-flat durability can be improved while suppressing an increase in the mass of.

  Further, the side reinforcing body 9 made of the strip laminated body 9m can be easily and freely changed in cross-sectional shape by changing the spiral winding pitch of the rubber strip 11 or the like. Therefore, the versatility is high and the productivity is excellent as compared with the conventional type in which the extruded rubber is spliced. In addition, since there is no rubber splice, the uniformity of the tire can be improved.

  Here, the rubber strip 11 preferably has a width RW of 10 to 30 mm and a thickness t1 of 0.6 to 2.0 mm. When the width RW of the rubber strip is less than 10 mm or when the thickness t1 is less than 0.6 mm, the rigidity becomes small, and the rubber strip 11 is easily broken by the tension at the time of winding. Moreover, in order to make a predetermined cross-sectional shape, the number of windings may increase remarkably, and productivity deteriorates. Conversely, when the width RW of the rubber strip 11 exceeds 30 mm or when the thickness t1 exceeds 2.0 mm, the cross-sectional shape of the strip laminate 9m tends to be rough.

  Further, the complex elastic modulus E * of the rubber strip 11 is not particularly limited, but if it is too small, the rigidity of the side reinforcing body 9 is insufficient, and there is a possibility that the vertical deflection during the run-flat running cannot be sufficiently suppressed. From such a viewpoint, the complex elastic modulus E * of the rubber strip 11 is preferably 2 MPa or more, more preferably 5 MPa or more, and further preferably 7 MPa or more. On the other hand, if the complex elastic modulus E * of the rubber strip 11 is too large, the ride comfort during normal running may be deteriorated. Therefore, the complex elastic modulus E * is preferably 150 MPa or less, more preferably 120 MPa or less, still more preferably 50 MPa or less, and particularly preferably 20 MPa or less.

  Further, the loss tangent tan δ of the rubber strip 11 is not particularly limited, but if it is too large, the rubber part 9A is likely to generate heat, which may deteriorate the durability of the side reinforcing body 9. From such a viewpoint, the loss tangent tan δ is preferably 0.3 or less, more preferably 0.1 or less, and still more preferably 0.08 or less. On the other hand, if the loss tangent tan δ of the rubber strip 11 is too small, the resilience elastic modulus increases, and the ride comfort during normal running may be deteriorated. Therefore, the loss tangent tan δ is preferably 0.02 or more. Preferably it is 0.03 or more, more preferably 0.04 or more.

  The complex elastic modulus and loss tangent of the rubber are as follows: a strip-shaped sample of 4 mm width × 30 mm length × 1.5 mm thickness and a viscoelastic spectrometer, temperature 70 ° C., frequency 10 Hz, and dynamic strain ± 2%. The value measured at.

Reinforcing cord layer 9B of the present embodiment, the cord ply 12 around the tire rotational axis, in the example of FIG. 1 (specifically 3 weeks) multiple peripheral is formed helically wound. Such a reinforcing cord layer 9B has a so-called jointless structure having no splice portion, so that the weight balance in the tire circumferential direction can be made uniform, and as a result, the uniformity of the tire can be improved.

  FIG. 5 shows the cord ply 12 before being formed into a tire. The cord ply 12 includes a plurality of cords 13 arranged in parallel, and an unvulcanized topping rubber 14 that covers the cord 13. In this example, the cord 13 is arranged substantially parallel to the width direction of the cord ply 12 (in other words, the cord 13 is arranged perpendicular to the length direction of the cord ply 12).

  As the cord 13, an organic fiber cord having a specific gravity smaller than that of the rubber composition of the rubber strip 11, such as nylon, polyester, rayon, polyethylene naphthalate (PEN), or aromatic polyamide, is preferably used. Further, the number of cords 13 to be driven can be appropriately determined as necessary, but is measured in a direction perpendicular to the longitudinal direction of the cords 13 in order to balance the reinforcing effect on the side reinforcing bodies 9 and the riding comfort. Further, 30 or more per 5 cm width, more preferably 40 or more are desirable, and the upper limit is preferably 60 or less, more preferably 55 or less.

  Such a cord ply 12 is spirally wound in the circumferential direction of the tire together with the rubber strip 11 so as to be incorporated into the side reinforcing body 9 to constitute the reinforcing cord layer 9B. Further, since the reinforcing cord layer 9B is covered with a rubber portion 9A made of the rubber strip 11, the cord 13 is prevented from coming into contact with the carcass cord or the inner liner rubber 10, and thus is prevented from being damaged. .

  Further, the cord 13 of the reinforcing cord layer 9B is desirably disposed at an angle θ of ± 30 degrees, more preferably ± 20 degrees, and further preferably ± 10 degrees with respect to the radial direction. FIG. 4 shows a partial side view of the side reinforcement 9 as seen from the outside in the tire axial direction. The “radial direction” is the direction RD of the cut surface of the tire cross section including the tire rotation axis. As shown in FIG. 3, such a reinforcing cord layer 9B can effectively hold the tire load acting on the side reinforcing body 9 by the bending rigidity or compression resistance rigidity of the cord 13 during run flat running, High load-bearing capacity can be achieved with a small mass and volume. This can reduce the amount of rubber part 9A used, and can greatly contribute to the reduction of tire mass. If the angle θ is larger than 30 degrees, the reinforcing effect on the side reinforcing bodies 9 may be reduced.

  When manufacturing such a run-flat tire 1, for example, as shown in FIGS. 5 and 6, the rubber strip 11 and the cord ply 12 are preliminarily stacked to form a composite strip 17, which is shown in FIG. As described above, it is desirable to form at least a part of the side reinforcing body 9 by spirally winding around a cylindrical body D such as a tire molding drum. By using such a composite strip 17, productivity is significantly improved as compared with the case where the rubber strip 11 and the cord ply 12 are individually wound.

  The side reinforcements 9 may all be formed from the composite strip 17. Such a side reinforcement body 9 can exhibit very high bending rigidity, and thus can run for a longer run flat. On the other hand, if the bending rigidity of the side reinforcing body 9 is excessively increased, the riding comfort during normal running tends to be deteriorated. For this reason, in order to achieve both ride comfort and run-flat performance, it is desirable to form a part of the side reinforcing body 9 with the composite strip 17 and the remainder with the rubber strip 11 alone.

  As an example, the total mass of the cord 13 with respect to the total mass of the side reinforcing body 9 is preferably 2% or more, more preferably 3% or more, and further preferably 5% or more. When the mass of the cord 13 is less than 2% of the total mass of the side reinforcement 9, there is a tendency that a sufficient reinforcing effect cannot be obtained. On the other hand, when the mass of the cord 13 is increased, the ride comfort may be remarkably deteriorated. Therefore, the proportion is preferably 50% or less, more preferably 45% or less, and further preferably 30% of the total mass of the side reinforcing body 9. The following is desirable.

  Further, the region where the reinforcing cord layer 9B is provided is not particularly limited. However, during the run-flat running, the tire load is supported mainly in the range of 20 to 70% of the length L from the inner end 9i of the side reinforcing body 9 to the outside, so the reinforcing cord layer 9B is disposed in this range. Is effective.

  The composite strip 17 is formed by a strip supply tool 30 as shown in FIG. The supply tool 30 includes a pair of pressing rollers R1 and R2 that can integrally press the rubber strip 11 and the cord ply 12 that are continuously supplied. By allowing the rubber strip 11 and the cord ply 12 to pass through the gap between the rollers R1 and R2, the members 11 and 12 are integrally pressed together to continuously form a composite strip 17 and to the wound body D. Can be supplied with.

  As shown in FIG. 6, the composite strip 17 of this example is bonded such that the rubber strip 11 and the cord ply 12 are substantially aligned with the center CL of each width. In addition, the width RW of the rubber strip 11 is larger than the width PW of the cord ply 12, and both side edges 11e of the rubber strip 11 protrude from the side edges 12e of the cord ply in the width direction. As a result, the composite strip 17 is provided with protruding portions 20 where the rubber strip 11 protrudes from the cord ply 12 on both sides in the width direction. The composite strip 17 can prevent the cord plies 12 from directly overlapping each other when wound together. Therefore, the cords 13 of the cord ply 12 come into contact with each other, and fretting damage caused by friction can be effectively prevented. Further, as the protruding portion 20 can be deformed flexibly, it effectively absorbs a step or the like during winding and serves to finish the cross-sectional shape of the side reinforcing body 9 with high accuracy.

  The width ST of the protruding portion 20 is not particularly limited. However, if the width ST is too small, it is difficult to obtain the above effect. Conversely, if the width ST is too large, the cross-sectional shape of the side reinforcing body 9 may be restricted. From this point of view, the length ST is preferably 2 mm or more, more preferably 3 mm or more, and the upper limit is preferably 10 mm or less, more preferably 8 mm or less.

In FIG. 7, an example of the manufacturing method of the run flat tire 1 of this embodiment is shown.
A sheet-like inner liner rubber 10 </ b> P is wound around a wound body D formed of a molding drum having a substantially cylindrical shape in advance according to a custom. In this embodiment, only the rubber strip 11 is wound around the outside first. That is, the strip supply tool 30 allows the cord ply 12 to stand by on the conveyor 22, while allowing only the rubber strip 11 to pass through the gap between the pressing rollers R1 and R2 and supply it to the wound body D.

  One end of the supplied rubber strip 11 is fixed to the outer side of the inner liner rubber 10 and the wound body D is around its center line (which is coaxial with the tire rotation axis later). Rotated. As a result, the rubber strip 11 is spirally wound around the inner liner rubber 10. At this time, the feed pitch of the composite strip 17 with respect to the wound body D in the tire axial direction (in this example, the outer side in the tire axial direction) is appropriately adjusted, and a part of the strip laminate 9m having a predetermined cross-sectional shape is formed. .

  Next, after the rubber strip 11 is wound a predetermined number of times, for example, the conveyor 22 holding the cord ply 12 is driven to supply the cord ply 12 to the upstream position of the pressing rollers R1 and R2. As a result, the end portion of the cord ply 12 can contact the rubber strip 11 being fed out and pass through the gap between the pressing rollers R1 and R2 together with this. Thereby, the strip supply tool 30 can supply the composite strip 17 to the wound body D. These steps may be performed by temporarily stopping the winding of the rubber strip 11 or may be performed continuously without stopping the winding. In any case, it is desirable from the viewpoint of productivity to be performed without cutting the rubber strip 11 at least.

  When the composite strip 17 supplied to the wound body D is wound around the predetermined position of the side reinforcing body 9 for the necessary number of turns, the cord ply 12 is cut by the cutting tool 23. Thereby, the strip supply tool 30 again supplies only the rubber strip 11 to the wound body D, the rubber strip 11 is cut at a necessary position, and the end portion thereof is fixed. By performing such a process, the cord ply 12 can be disposed inside the side reinforcing body 9 and in a predetermined position in a state of being completely covered with the rubber strip 11.

  Thereafter, the carcass ply 6A, the bead core 5, the bead apex 8 and the like are set outside the side reinforcing body 9, and the carcass ply 6A is turned back. Further, the sidewall rubber 3G and the clinch rubber 4G are further arranged on the outer side. Thereafter, the tread region is projected outward in the tire radial direction while the interval between the bead cores 5 and 5 is reduced, so that the ring-shaped belt layer 7 and the tread rubber 2G waiting in advance are combined. Thereby, the raw cover 1L as shown in FIG. 8 is obtained. And the run-flat tire 1 of this embodiment is manufactured by vulcanization-molding this raw cover 1L.

  In the raw cover molding method as described above, when the position and shape of the side reinforcing body 9 cannot be stably molded, for example, a core molding method can be used. The core molding method is, for example, attaching a necessary rubber material and ply around an assembly core (not shown, but this is a wound body), vulcanizing as it is, and then disassembling the core. This is done by taking it out. In this molding method, the side reinforcement body 9 can be molded with high accuracy, and a carcass shaping step is not required. Therefore, the cord 13 of the reinforcement cord layer 9B can be inclined at an angle close to the tire circumferential direction.

Moreover, in the said embodiment, although the aspect which winds the rubber strip 11 and the composite strip 17 toward the outer side of the axial direction of the to-be-wrapped body D was shown, it can also wind toward the inner side. Further, for example, as schematically shown in FIG. 9, the composite strip 17 is wound around the first side S <b> 1 in the axial direction of the molding drum D and the shaft of the wound body D. And a second winding stage wound toward the other side S2 of the direction. During this time, the rubber strip 11 or the composite strip 17 is folded back and wound continuously at an arbitrary position (in this embodiment, one end portion of the side reinforcing body 9). It should be noted that during the first and second winding stages, the composite strip 17 may be continuous or fed separately (the latter in the present embodiment). Thus, the side reinforcing member 9, whereas a first layer 9a of the rubber strip 11 and the composite strip 17 is wound toward the side S1, a second layer 9b wound toward the other side S2 is superimposed To be formed.

  In FIG. 10, the fragmentary sectional view of the run flat tire using such a side reinforcement body 9 is shown. As is apparent from FIG. 10, in the side reinforcing body 9 of this embodiment, the rubber strips 11 are connected to each other in the first layer 9 i and the second layer 9 o. Thereby, the interface E of the rubber strip 11 extends in a substantially V shape that is convex toward the tread portion 2 side in this figure.

  A run-flat tire having a side reinforcing body 9 formed using a rubber strip is subjected to a durability test until the tire breaks. As a result, the side reinforcing body 9 is cracked along the interface E of the rubber strip 11. It turns out that there are many cases. Therefore, as in this embodiment, the rubber strips 11 of the first layer 9a and the second layer 9b are connected in a substantially V shape, so that the length of the interface E is longer than that in the embodiment of FIG. Can be increased. Thereby, the crack along the interface E needs to grow a longer distance in order to divide the side reinforcing body 9. That is, the durability of the side reinforcing body 9 is improved.

  The reinforcing cord layer 9Bi provided on the first layer 9a is provided with the reinforcing cord provided on the second layer 9b while each cord 13 is inclined outward in the tire axial direction toward the tread portion 2 side in the tire cross section. The cord layer 9Bo is arranged such that each cord 13 is inclined inward in the tire axial direction toward the tread portion 2 side. Since the inclination of the cord 13 follows the shape of the side reinforcing body 9 having a substantially crescent-shaped cross section, the rubber portion 9A is not unduly deformed during the run-flat travel. Therefore, looseness with the rubber portion 9A, rubber chipping, and the like can be effectively prevented.

  Further, the cords 13 are arranged separately on the outer side and the inner side in the tire radial direction of the side reinforcing body 9 and are provided without intersecting the tire axial line MP passing through the tire maximum width point M. For this reason, it is possible to prevent a significant deterioration in riding comfort during normal driving.

  In the above-described embodiment, the side reinforcement body 9 is formed by one turn, but the side reinforcement body 9 can also be formed by overlapping two or more turns. Such a side reinforcement body 9 can have a longer interface E length by connecting the rubber strips 11 of each layer in a zigzag shape. Therefore, since it takes time to grow the crack, the durability can be further improved.

  The side reinforcing body 9 can be molded by various methods other than the method using the rubber strip 11. For example, the rubber part 9A may be a molded product extruded from an extruder or the like. In this case, the rubber part 9A is, for example, divided into an inner part and an outer part in the tire axial direction, respectively, and extruded. The side reinforcement body 9 can be molded by sandwiching the cord ply 12 between them.

Next, a profile (contour line) of a preferred embodiment of a tire outer surface that may come into contact with the road surface including the tread portion 2 will be described. FIG. 11 shows a profile TL of the tire outer surface in a normal no-load state. The profile TL is specified excluding the groove of the tread portion 2. When the point on the tire outer surface that separates the distance SP of 45% of the maximum tire width SW from the intersection CP of the tire outer surface and the tire equator C in the normal no-load state is P, the distance from the intersection CP to the point P It is desirable to gradually decrease the radius of curvature RC of the tire outer surface in the section and satisfy the following relationship.
0.05 <Y60 / H ≦ 0.1
0.1 <Y75 / H ≦ 0.2
0.2 <Y90 / H ≦ 0.4
0.4 <Y100 / H ≦ 0.7
Here, Y60, Y75, Y90, and Y100 separate the tire axial distances of 60%, 75%, 90%, and 100% of the half width (SW / 2) of the maximum tire width in the tire axial direction from the tire equator C, respectively. The distances in the tire radial direction between the points P60, P75, P90 and P100 on the tire outer surface and the intersection point CP. The “H” is a tire cross-sectional height.

RY60 = Y60 / H
RY75 = Y75 / H
RY90 = Y90 / H
RY100 = Y100 / H
Then, the range satisfying the relationship is shown as a graph in FIG. As is apparent from FIGS. 11 and 12, the profile TL of the tire outer surface that satisfies the above relationship is very round. For this reason, the contact shape of a tire having such a profile TL has a small contact width and a large contact length. This helps to improve noise performance and hydroplaning performance.

  Moreover, such a profile increases the area of the tread that is easily bent, but has a feature that the area of the sidewall portion 3 is shortened. For this reason, the run-flat tire 1 having the profile has a reduced longitudinal spring and excellent ride comfort, and the length and rubber volume of the side reinforcing body 9 can be reduced, and a mass reduction in the run-flat tire is achieved. Is particularly preferable. The curvature radius RC may be reduced stepwise, but it is preferable that the curvature radius RC is continuously reduced as in the present embodiment.

  The present invention is particularly suitable for a passenger car, but it is needless to say that the present invention is not limited to the illustrated embodiment and can be implemented in various forms.

In order to confirm the effect of the present invention, the following performance was tested for a run-flat tire having a tire size “245 / 40R18” based on the specifications in Table 1. In each of the run flat tires of the examples, the side reinforcing body is composed of a rubber portion and a reinforcing cord layer, and Reference Example 1, Examples 2, and 3 have the basic structure shown in FIG. In addition, as shown in FIG. 10, the reference example 2 has a side reinforcing body formed by folding the strip around one end of the side reinforcing body and winding it (the position of the reinforcing cord layer is also shown in FIG. 10). Street.) Moreover, the total mass of the cord with respect to the total mass of the side reinforcement body was changed by changing the number of turns of the cord ply in any of the examples.

The specifications of the rubber strip and the reinforcing cord layer are as follows.
<Rubber strip>
Width RW: 20mm
Thickness t1: 1mm
Complex elastic modulus E *: 11 MPa
Loss tangent tan δ: 0.05
<Reinforcement cord layer>
Width PW: 15mm
Thickness t2: 1mm
End of cord ply: 45 / 5cm

Moreover, Comparative Examples 1 and 2 were prepared as run flat tires outside the present invention. In Comparative Example 1, the portion of the reinforcing cord layer of the side reinforcing body of Reference Example 1 is replaced with rubber so that the tire mass does not change. In Comparative Example 2, a single reinforcing cord layer made of nylon cord is disposed between the side reinforcing body and the carcass ply of the run-flat tire of Comparative Example 1. The examples and comparative examples have a common structure except for the side reinforcement.
The test method is as follows.

<Runflat durability>
Each test tire was assembled on the rim described below, filled with an internal pressure of 230 kPa, and allowed to stand at a temperature of 38 ° C. for 34 hours, and then the valve core of the rim was removed to allow the tire lumen to communicate freely with the atmosphere. And in this state, it was made to run on the drum test machine which has a drum with a radius of 1.7 m on the following conditions, and the running distance until a tire broke was measured. The results were expressed as an index with Comparative Example 1 as 100. The larger the value, the better.
Rims: 18 x 8.5 JJ
Speed: 80km / h
Longitudinal load: 4.14kN

<Tire mass>
The mass of each test tire was measured. The results are shown as an index with Comparative Example 1 as 100. A smaller number indicates a lighter weight.

<Uniformity>
In accordance with JASOc607, the primary radial force variation (RFV) of each test tire was measured and displayed as an index with Comparative Example 1 as 100. The smaller the value, the better the uniformity.

<Ride comfort (actual vehicle evaluation)>
4300cm ^{3 Japanese} FR car fitted with 4 test tires, stepped on dry asphalt road, Belgian road (cobblestone road), Bitzmann road (road surface covered with pebbles) under the above rim and internal pressure of 230kPa ), Etc., sensory evaluation was performed with respect to ruggedness, push-up, and damping, and evaluation was performed with a score of Comparative Example 1 being 100 points. The larger the value, the better.
Table 1 shows the test results.

  As a result of the test, it was confirmed that the tires of the examples improved the run-flat durability without increasing the tire mass as compared with the comparative examples. It was also confirmed that Examples 1 to 3 and Comparative Example 1 had no substantial difference in ride comfort.

It is sectional drawing of the run flat tire which shows embodiment of this invention. It is the principal part enlarged view. It is sectional drawing of the tire which shows the run flat state. It is a side view of a side reinforcement body. It is a perspective view which shows an example of the process of manufacturing a composite strip. It is sectional drawing of the composite strip. It is sectional drawing explaining the manufacturing method of a run flat tire. It is sectional drawing of the raw cover shape | molded by it. It is a diagram which shows the winding method of the rubber strip which shows other embodiment of this invention. It is sectional drawing of the run flat tire which shows other embodiment of this invention. It is a diagram which shows the profile of a tire outer surface. It is a diagram which shows the range of RYi in each position of a tire outer surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Run flat tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 9 Side reinforcement 9A Rubber part 9B Reinforcement cord layer 11 Rubber strip 12 Cord ply 13 Cord 14 Topping rubber 17 Composite strip E Rubber strip interface

Claims (9)

A run-flat tire comprising a toroidal carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a side reinforcing body disposed inside the carcass and having a substantially crescent-shaped cross section,
The side reinforcing member is seen containing a rubber portion and a reinforcing cord layer covered by said rubber portion,
The rubber part is formed by winding a ribbon-shaped rubber strip spirally around the tire rotation axis,
The reinforcing cord layer is formed by winding a ribbon-like cord ply in which cords are arranged at right angles to the length direction and wound around the tire rotation axis in a spiral manner. tire.
The run-flat tire according to claim 1 , wherein each of the reinforcing cord layers is inclined outward in the tire axial direction toward the tread portion side in a tire cross section .
The side reinforcement includes a first layer in which the rubber strip and the cord ply are wound from an outer end in the tire radial direction toward an inner end of the side reinforcement, and an inner end in the tire radial direction of the side reinforcement. And a second layer around which the rubber strip and the cord ply are wound toward the outer end,
The reinforcing cord layer provided in the first layer, each cord is inclined in the tire axial direction outward toward the tread portion side in the tire cross section,
The reinforcing cord layer provided in the second layer, each cord is inclined inward in the tire axial direction toward the tread portion side in the tire cross section,
Each cord of the reinforcing cord layer provided in the first layer and the second layer is arranged separately on the outer side and the inner side in the tire radial direction of the side reinforcing body, and passes through the tire maximum width point. The run-flat tire according to claim 1 or 2, provided without intersecting the direction line .
  The run-flat tire according to claim 3, wherein the reinforcing cord layers are wound without overlapping each other.   The run-flat tire according to any one of claims 1 to 4, wherein the reinforcing cord layer has a cord having an angle of ± 30 degrees with respect to a radial direction. In the tire meridian cross section including the tire rotation shaft in the normal unloaded state in which the rim is assembled to the regular rim and filled with the regular internal pressure,
The profile of the tire outer surface is defined as a point on the tire outer surface (P) that is separated from the intersection (CP) of the tire outer surface and the tire equator (C) by a distance (SP) of 45% of the maximum tire width (SW). In the section from the intersection (CP) to the point (P), the radius of curvature (RC) of the tire outer surface gradually decreases,
The run-flat tire according to any one of claims 1 to 5, which satisfies the following relationship.
0.05 <Y60 / H ≦ 0.1
0.1 <Y75 / H ≦ 0.2
0.2 <Y90 / H ≦ 0.4
0.4 <Y100 / H ≦ 0.7
(Where Y60, Y75, Y90 and Y100 are the tire axial distances of 60%, 75%, 90% and 100% of the half width (SW / 2) of the maximum tire width in the tire axial direction from the intersection (CP). (The distances in the tire radial direction between the points P60, P75, P90 and P100 on the outer surface of the tire and the intersections (CP), and H is the tire cross-section height.) A method for producing a run-flat tire comprising a toroid-like carcass extending from a tread portion through a sidewall portion to a bead core of the bead portion, and a side reinforcing body disposed inside the carcass and having a substantially crescent-shaped cross section. Because
Forming a composite strip by overlapping a ribbon-like rubber strip and a ribbon-like cord ply in which cords are arranged perpendicular to the length direction ;
And a step of forming at least a part of the side reinforcing body by winding the composite strip spirally around the cylindrical body to be wound a plurality of times .
  The method of manufacturing a run-flat tire according to claim 7, wherein the composite strip has a width of the rubber strip larger than a width of the cord ply, and both side edges of the rubber strip protrude from both side edges of the cord ply. .   The step of winding the composite strip includes a first winding step of winding toward one side of the wound body in the axial direction and a second winding of winding toward the other side of the wound body in the axial direction. A method for manufacturing a run-flat tire according to claim 7 or 8, comprising a winding step.

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