JP2017124752A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire achieving weight saving thereof without lowering a rim assemblability nor generating a step on the tire surface.SOLUTION: In a pneumatic tire, when defining: a tire sectional height which is a tire radial distance between a portion located in an outermost side in a tire radial direction in a tread part 2, and a rim base line BL as HS; a bead filler height which is the tire radial distance between the bead filler end 25 of a bead filler 24, and the rim base line BL as HB; and a carcass end height which is the tire radial distance between the carcass end 36 and the rim base line BL as HC, the HS, HB and HC have the relations satisfying (HB/HS)<0.25 and 0.25<(HC/HS)<0.5. Besides, a reinforcement layer 40 which includes a rubber in which a modulus at 100% elongation is 120% or more but 250% or less of a side rubber 11 and is disposed along a carcass layer 30 and apart from the carcass end 36 is provided outside the carcass end 36 in the tire radial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire.

  In general, many pneumatic tires are configured such that a carcass is disposed between bead portions disposed on both sides in the tire width direction, and the carcass is folded at the bead portion so as to wind a bead core. In addition, various performances are required for pneumatic tires, but in some conventional pneumatic tires, a reinforcing layer is provided in the vicinity of the folded portion of the carcass in order to improve multiple performances. There is something that is.

  For example, in the pneumatic tire described in Patent Document 1, in order to reduce rolling resistance without sacrificing steering stability and riding comfort performance, a belt end disposed on the tread portion side and a carcass turn-back are provided. A short fiber reinforcing layer is disposed in the sidewall region between the ends. Moreover, in the pneumatic tire described in Patent Document 2, a fiber reinforcement layer is laminated on a bead filler in order to obtain a light weight and excellent steering stability. Further, the pneumatic tire described in Patent Document 3 is arranged from the outer end of the bead filler in the tire radial direction to the maximum width end of the belt portion in order to improve the handling stability without impairing the riding comfort performance and durability. The reinforcing layer is disposed over 35% of the total.

JP-A-8-175119 JP 2007-176215 A JP-A-10-53010

  Here, as one of the performance required for pneumatic tires, weight reduction is also an important performance, but when the thickness of the rubber of the sidewall portion is reduced for the purpose of weight reduction, when inflating, There may be a step on the tire surface at the end of the carcass. In particular, when a tire such as a puncture occurs in a vehicle, a so-called temporary tire is a tire that is used for temporary use by replacing it with a defective tire. Therefore, a step on the tire surface at the end of the carcass is more likely to appear than a normal pneumatic tire.

  Further, since the carcass is folded at the bead portion, the rigidity difference between the inner region and the outer region in the tire radial direction starting from the folded end is large in the sidewall portion. When the thickness is reduced, this difference in rigidity is more likely to appear.

  The step appearing on the tire surface can be eliminated by providing a reinforcing layer that covers the end of the carcass, but if the end of the carcass is covered with a reinforcing layer, the rigidity is improved even when the reinforcing layer is not provided. The rigidity of the region on the bead portion side that is higher is further increased. In this case, since the rigidity of the bead portion becomes too high, there is a possibility that the rim assembling property is lowered. In addition, the step appearing on the tire surface can be eliminated by increasing the thickness of the rubber on the sidewall, but if the thickness of the rubber on the sidewall is increased, It becomes impossible to reduce the weight of the tire.

  The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can be reduced in weight without deteriorating the rim assembly property and without generating a step on the tire surface. To do.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is provided with a tread portion having a tread surface and an inner side in the tire radial direction from both ends of the tread portion in the tire width direction. A sidewall portion provided; a bead portion disposed on a tire radial direction side of the sidewall portion; a bead core disposed on the bead portion; and a bead filler disposed on the outer side of the bead core in the tire radial direction. The carcass cords are arranged at an angle of 20 ° to 50 ° with respect to the tire circumferential direction and the carcass cords are arranged to intersect with each other, A carcass layer disposed between the bead portions and folded around the bead core, wherein the carcass layer is a folded portion. A carcass end that is an end on the outer side in the tire radial direction in a certain turn-up portion is in contact with a portion located on the inner side in the tire width direction with respect to the turn-up portion in the carcass layer, and in the tread portion The tire cross-section height HS, which is the distance in the tire radial direction between the portion positioned on the outermost side in the tire radial direction and the rim base line, the end on the outer side in the tire radial direction in the bead filler, and the rim base The relationship between the bead filler height HB that is the distance in the tire radial direction from the line and the carcass end height HC that is the distance in the tire radial direction between the carcass end and the rim base line is {(HB /HS)<0.25} and {0.25 <(HC / HS) <0.5}, and the carcass end has a 100% elongation on the outer side in the tire radial direction. A reinforcing layer is provided that includes a rubber whose modulus of time is 120% or more and 250% or less of the rubber constituting the sidewall portion, and that is disposed along the carcass layer and spaced from the end portion of the carcass. It is characterized by.

  In the pneumatic tire, the reinforcing layer has a distance between a lower end in the tire radial direction and the carcass end of 5 mm or more and 20 mm or less, and an end on the outer side in the tire radial direction of the reinforcing layer. A reinforcing layer upper end height HM that is a distance in the tire radial direction between the upper end portion of the reinforcing layer that is a portion and the carcass end portion, shoulder edges that are located at both ends of the tread portion in the tire width direction, and the carcass end portion It is preferable that the upper end portion of the reinforcing layer is located at a position where the shoulder edge height HE which is the distance in the tire radial direction satisfies {(HM / HE) ≦ 0.6}.

  Moreover, the said pneumatic tire WHEREIN: It is preferable that the said reinforcement layer is an organic fiber reinforcement layer which has an organic fiber member.

  In the pneumatic tire, the reinforcing layer has a relationship in which the cord diameter DM of the organic fiber member and the cord diameter DC of the carcass cord satisfy {0.6 ≦ (DM / DC) ≦ 0.9}. It is preferable to satisfy.

  In the pneumatic tire, the reinforcing layer includes a cord angle AM of the organic fiber member with respect to a tire circumferential direction, and a cord angle AC with respect to the tire circumferential direction of the carcass cord in the turn-up portion of the carcass layer. It is preferable to satisfy the relationship of {−20 ° ≦ (AC−AM) ≦ −5 °}.

  In the pneumatic tire, in the reinforcing layer, the density EM of the organic fiber member and the density EC of the carcass cord satisfy a relationship of {0.65 ≦ (EM / EC) ≦ 0.95}. It is preferable.

  In the pneumatic tire, it is preferable that the pneumatic tire is a temporary tire that is used as an emergency when a pneumatic tire mounted on a vehicle fails.

  The pneumatic tire according to the present invention has an effect that it is possible to reduce the weight without reducing the rim assembly property and without generating a step on the tire surface.

FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. FIG. 2 is an explanatory diagram of the carcass cord viewed from the AA direction in FIG. FIG. 3 is an explanatory diagram showing a form of arrangement of the reinforcing layers shown in FIG. FIG. 4 is an explanatory diagram of a reinforcing layer cord and a carcass cord viewed from the BB direction in FIG. 3. FIG. 5 is an explanatory diagram of the reinforcing layer cord viewed from the CC direction of FIG. FIG. 6 is an explanatory diagram of the carcass cord viewed from the DD direction in FIG. FIG. 7A is a chart showing the results of a performance test of a pneumatic tire. FIG. 7B is a chart showing the results of the performance test of the pneumatic tire. FIG. 7C is a chart showing the results of the performance test of the pneumatic tire.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced by those skilled in the art and can be easily conceived, or those that are substantially the same.

  In the following description, the tire width direction refers to the direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction is the direction toward the tire equatorial plane in the tire width direction, and the outer side in the tire width direction is The direction opposite to the direction toward the tire equatorial plane in the tire width direction. The tire radial direction means a direction orthogonal to the tire rotation axis, the tire radial inner direction means the direction toward the tire rotation axis in the tire radial direction, and the tire radial direction outer direction means that the tire rotates in the tire radial direction. The direction away from the axis. Further, the tire circumferential direction refers to a direction rotating around the tire rotation axis.

  FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. The pneumatic tire 1 shown in FIG. 1 has a tread portion 2 disposed on the outermost portion in the tire radial direction when viewed in the meridional section, and the surface of the tread portion 2, that is, the pneumatic tire. A portion that comes into contact with the road surface when the vehicle (not shown) on which the vehicle 1 is mounted is formed as a tread surface 3. Both ends of the tread portion 2 in the tire width direction are formed as shoulder portions 4, and sidewall portions 10 are provided. That is, the sidewall portion 10 is disposed from both ends of the tread portion 2 in the tire width direction toward the inside in the tire radial direction, and is disposed at two positions on both sides of the pneumatic tire 1 in the tire width direction. .

  Further, a bead portion 20 is disposed on the inner side in the tire radial direction of each sidewall portion 10, and the bead portion 20 is provided at two locations on both sides of the tire equatorial plane CL, similarly to the sidewall portion 10. It is arranged. That is, a pair of bead portions 20 is disposed on both sides of the tire equatorial plane CL in the tire width direction. Each of the pair of bead portions 20 is provided with a bead core 21, and a bead filler 24 is disposed on the outer side of each bead core 21 in the tire radial direction. The bead filler 24 is a rubber material disposed in a space formed by folding an end portion in the tire width direction of a carcass layer 30 to be described later outward in the tire width direction at the position of the bead core 21.

  A breaker 6 is disposed inside the tread portion 2 in the tire radial direction. The breaker 6 has, for example, a multilayer structure in which a first breaker 7 and a second breaker 8 are stacked, and is configured by coating a plurality of breaker cords made of an organic fiber material such as nylon with a coat rubber and rolling it. The breaker 6 is configured such that the angle of the breaker cord with respect to the tire circumferential direction is inclined at an angle of 30 ° or more and 40 ° or less in absolute value. The first breaker 7 and the second breaker 8 are arranged in the tire circumferential direction. The inclination angles of the breaker cord with respect to are different from each other. In other words, the breaker 6 having the first breaker 7 and the second breaker 8 is configured as a so-called cross-ply structure in which the breaker cord directions are stacked so as to cross each other.

  In the first breaker 7 and the second breaker 8, the first breaker 7 is disposed on the inner side in the tire radial direction, and the second breaker 8 is arranged on the outer side in the tire radial direction of the first breaker 7. It is laminated on the breaker 7. Further, the second breaker 8 has a width in the tire width direction wider than the width of the first breaker 7 in the same direction.

  A carcass layer 30 containing a textile cord of the bias ply is disposed between the bead portions 20 on both sides in the tire width direction on the inner side in the tire radial direction of the breaker 6 and on the tire equatorial plane CL side of the sidewall portion 10. Are provided continuously. The carcass layer 30 has a multilayer structure formed by laminating two carcasses 31 of a first carcass 32 and a second carcass 33, and is formed in a toroidal shape between bead cores 21 disposed on both sides in the tire width direction. It is bridged to form the tire skeleton.

  Specifically, the carcass layer 30 is disposed from one bead portion 20 to the other bead portion 20 of the pair of bead portions 20 located on both sides in the tire width direction, and wraps the bead core 21 and the bead filler 24. Thus, the bead portion 20 is wound back along the bead core 21 outward in the tire width direction. That is, the carcass layer 30 is disposed around the bead core 21 at the bead portion 20 so as to be disposed from the inner side in the tire width direction of the bead core 21 to the inner side in the tire radial direction of the bead core 21 and outward in the tire width direction of the bead core 21. The portion folded back around the bead core 21 is provided as a turn-up portion 35.

  The first carcass 32 and the second carcass 33 are such that the first carcass 32 is positioned inside the pneumatic tire 1, and the second carcass 33 is laminated on the first carcass 32 outside the first carcass 32. Arranged. Specifically, at the position of the tread portion 2, the second carcass 33 is laminated on the first carcass 32 on the outer side in the tire radial direction of the first carcass 32, and other than the turn-up portion 35 at the position of the sidewall portion 10. In the portion, the second carcass 33 is laminated on the first carcass 32 on the outer side in the tire width direction of the first carcass 32. Further, since the first carcass 32 and the second carcass 33 are folded around the bead core 21 in a stacked state, the first carcass 32 is stacked on the outer side in the tire width direction of the second carcass 33 in the turnup portion 35. Arranged.

  The first carcass 32 and the second carcass 33 located in the turn-up portion 35 are in contact with the carcass main body portion 34 that is a portion other than the turn-up portion 35 in the carcass layer 30 in the vicinity of the outer end portion in the tire radial direction. doing. Specifically, the second carcass 33 located on the inner side of the carcass layer 30 around the bead core 21 is located near the end portion on the outer side in the tire radial direction in the portion on the turn-up portion 35 side. It is in contact with the part on the carcass main body 34 side. That is, the end portion on the outer side in the tire radial direction of the portion on the turn-up portion 35 side in the second carcass 33 is more tire than the bead filler end portion 25 that is the end portion on the outer side in the tire radial direction in the bead filler 24. Thus, the second carcass 33 is in contact with the carcass main body 34 in the vicinity of the end portion on the outer side in the tire radial direction of the turn-up portion 35 side of the second carcass 33.

  Further, in the turn-up portion 35, the first carcass 32 and the second carcass 33 are arranged farther in the tire radial direction than the second carcass 33. For this reason, the first carcass 32 is located near the end portion on the outer side in the tire radial direction in the portion on the turnup portion 35 side from the position where the turnup portion 35 of the second carcass 33 is in contact with the carcass main body portion 34. Also, at the position on the outer side in the tire radial direction, the second carcass 33 is in contact with the portion on the carcass body 34 side.

  That is, the carcass layer 30 has a carcass end portion 36 that is an end portion on the outer side in the tire radial direction of the turn-up portion 35 at a portion located on the inner side in the tire width direction of the turn-up portion 35 in the carcass layer 30. It touches. In the carcass end portion 36 in this case, the end portion on the outer side in the tire radial direction of the turn-up portion 35 is located on the outer side in the tire radial direction with respect to the end portion on the outer side in the tire radial direction of the second carcass 33. The first carcass 32 is an end portion on the outer side in the tire radial direction.

  FIG. 2 is an explanatory diagram of the carcass cord viewed from the AA direction in FIG. The carcass 31 of the carcass layer 30 is formed by rolling a plurality of carcass cords 38 made of steel or an organic fiber material such as aramid, nylon, polyester, rayon, etc. with a coat rubber. These carcass cords 38 are disposed so as to be inclined at an angle θ of 20 ° or more and 50 ° or less in absolute value with respect to the tire circumferential direction. Further, the carcass layer 30 is arranged such that the carcass cord 38 of the first carcass 32 and the carcass cord 38 of the second carcass 33 intersect each other.

  Further, an inner liner 15 is formed along the carcass layer 30 on the inner side of the carcass layer 30 or on the inner side of the carcass layer 30 in the pneumatic tire 1.

  In the pneumatic tire 1 configured as described above, the relationship between the tire cross-section height HS with respect to the rim base line BL, the bead filler height HB, and the carcass end height HC is {(HB / HS) <0.25} and {0.25 <(HC / HS) <0.5}. Among these, the tire cross-section height HS is the distance in the tire radial direction between the rim base line BL and the portion of the tread portion 2 that is located on the outermost side in the tire radial direction. Further, the bead filler height HB is the distance in the tire radial direction between the bead filler end 25 and the rim base line BL. Further, the carcass end height HC is the distance in the tire radial direction between the carcass end 36 and the rim base line BL. Further, the rim base line BL here is a tire axial direction line passing through a rim diameter defined by JATMA standards.

  Furthermore, in the pneumatic tire 1 according to the present embodiment, the carcass end portion 36 in the sidewall portion 10 is disposed on the outer side in the tire radial direction along the carcass layer 30 and spaced from the carcass end portion 36. A reinforcing layer 40 is provided.

  FIG. 3 is an explanatory diagram showing a form of arrangement of the reinforcing layers shown in FIG. The reinforcing layer 40 is disposed along the carcass layer 30 outside the carcass layer 30 in the tire width direction, and the distance S between the reinforcing layer lower end portion 42 that is the lower end in the tire radial direction and the carcass end portion 36 is set. It is spaced apart from the carcass end 36 to the outer side in the tire radial direction within a range of 5 mm to 20 mm.

  Further, in the reinforcing layer 40, the relationship between the reinforcing layer upper end height HM and the shoulder edge height HE when the carcass end portion 36 is used as a reference satisfies the position {(HM / HE) ≦ 0.6}. A reinforcing layer upper end portion 41 which is an end portion on the outer side in the tire radial direction of the reinforcing layer 40 is located and disposed. Among these, the reinforcing layer upper end height HM is the distance in the tire radial direction between the reinforcing layer upper end 41 and the carcass end 36. The shoulder edge height HE is formed in the shoulder portion 4, and the tire edge direction between the shoulder edge 5 and the carcass end portion 36 located at the boundary between the surface of the sidewall portion 10 in the tire width direction and the tread surface 3. It is a distance.

  The tire cross-section height HS, the bead filler height HB, the carcass end height HC, the reinforcement layer upper end height HM, and the shoulder edge height HE for defining the form of the pneumatic tire 1 and the reinforcing layer 40 are as follows: The pneumatic tire 1 is fixed to the measurement rim width and is a value measured in a no-inflation state. The measurement rim in this case is a rim conforming to “Applied rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO.

  The reinforcing layer 40 disposed along the carcass layer 30 is an organic layer formed by rolling a plurality of reinforcing layer cords 45 made of organic fiber members such as aramid, nylon, polyester, rayon, etc. with a coating rubber. It is provided as a fiber reinforced layer. The rubber used for the reinforcing layer 40 has a modulus at 100% elongation (a tensile stress obtained when 100% elongation is given to the test piece obtained in accordance with JIS K6251: 2010) constitutes the sidewall portion 10. The rubber which is 120% or more and 250% or less of the side rubber 11 which is the rubber to be used is included.

  FIG. 4 is an explanatory diagram of a reinforcing layer cord and a carcass cord viewed from the BB direction in FIG. 3. In the reinforcing layer 40, the cord angle AM of the reinforcing layer cord 45 with respect to the tire circumferential direction and the cord angle AC with respect to the tire circumferential direction of the carcass cord 38 in the turn-up portion 35 of the carcass layer 30 are {−20 ° ≦ (AC− AM) ≦ −5 °} so as to satisfy the relationship. That is, the reinforcing layer 40 is formed such that the cord angle AM of the reinforcing layer cord 45 with respect to the tire circumferential direction is smaller than the cord angle AC of the carcass cord 38 of the turnup portion 35 with respect to the tire circumferential direction. In other words, in the reinforcing layer 40, the inclination angle of the reinforcing layer cord 45 with respect to the tire radial direction is larger than the inclination angle of the carcass cord 38 of the turn-up portion 35 with respect to the tire radial direction.

  FIG. 5 is an explanatory diagram of the reinforcing layer cord viewed from the CC direction of FIG. FIG. 6 is an explanatory diagram of the carcass cord viewed from the DD direction in FIG. In the reinforcing layer 40, the cord diameter DM of the reinforcing layer cord 45 and the cord diameter DC of the carcass cord 38 included in the carcass layer 30 satisfy the relationship {0.6 ≦ (DM / DC) ≦ 0.9}. Yes. That is, in the reinforcing layer 40, the cord diameter DM of the reinforcing layer cord 45 is 0.6 to 0.9 times the cord diameter DC of the carcass cord 38.

Further, in the reinforcing layer 40, the density EM of the reinforcing layer cord 45 and the density EC of the carcass cord 38 included in the carcass layer 30 satisfy the relationship {0.65 ≦ (EM / EC) ≦ 0.95}. Yes. In this case, the density EM of the reinforcing layer cord 45 is the average number of the reinforcing layer cords 45 per unit area in the cross section orthogonal to the extending direction of the reinforcing layer cord 45 in the reinforcing layer 40. The density EC of the carcass cords 38 is the average number of carcass cords 38 per unit area in a cross section perpendicular to the extending direction of the carcass cords 38 in the carcass layer 30. In the reinforcing layer 40, the density EM [lines / mm ² ] of the reinforcing layer cord 45 defined as described above is 0.65 times or more 0.95 with respect to the density EC [lines / mm ² ] of the carcass cord 38. It is within the range of less than double.

  The pneumatic tire 1 according to the present embodiment configured as described above is used as a so-called temporary tire that is used as an emergency when a pneumatic tire mounted on a vehicle fails. The temporary tire is normally mounted on the vehicle without being used for running the vehicle, and is temporarily used by being mounted on the vehicle when a pneumatic tire mounted on the vehicle for running the vehicle fails. On the other hand, one of the performances required for the pneumatic tire 1 is weight reduction. Since the temporary tire is normally mounted on the vehicle, the weight of the temporary tire when the vehicle is running is also included. In order to reduce fuel consumption and improve fuel efficiency and driving performance, it is important to reduce weight.

  In order to reduce the weight of the pneumatic tire 1, it is effective to make the rubber gauge Ga (see FIG. 1) of the sidewall portion 10 thinner. However, when the rubber gauge Ga of the sidewall portion 10 is reduced, a step is likely to occur on the tire surface 12 at the carcass end portion 36 of the turn-up portion 35 of the carcass layer 30 during inflation. In particular, in the temporary tire, the air pressure at the time of inflation is higher than that of a pneumatic tire that is normally attached to the vehicle, and is used at a pressure of about 420 kPa, for example. For this reason, the pneumatic tire 1 according to the present embodiment is also used at a higher air pressure than the pneumatic tire that is normally mounted on the vehicle. On the tire surface 12, the portion of the carcass end portion 36 of the turn-up portion 35 is used. It becomes easy to be influenced by nearby shapes.

  Here, on the outer side in the tire radial direction of the carcass end portion 36, the reinforcing layer 40 along the carcass layer 30 is disposed apart from the carcass end portion 36. As a result, the rubber gauge Ga is not rapidly reduced in the portion of the carcass end portion 36 on the outer side in the tire radial direction, so that the occurrence of a step on the tire surface 12 near the carcass end portion 36 can be suppressed. Further, since the reinforcing layer 40 does not overlap with the turn-up portion 35 of the carcass layer 30, it is possible to suppress the occurrence of a step on the tire surface 12 due to the overlapping of the reinforcing layer 40 and the turn-up portion 35.

  Further, since the reinforcing layer 40 does not overlap with the turn-up portion 35 of the carcass layer 30 as described above, it is possible to suppress the rigidity of the bead portion 20 from becoming too high due to the provision of the reinforcing layer 40. That is, when the rigidity of the bead portion 20 becomes excessively high, when the pneumatic tire 1 is incorporated into the specified rim, it is difficult to incorporate the pneumatic tire 1 into the rim due to the high rigidity, and the rim assemblability is deteriorated. However, in the pneumatic tire 1 according to the present embodiment, it is possible to suppress the rigidity of the bead portion 20 from becoming too high, and thus it is possible to suppress a decrease in rim assemblability.

  Specifically, in the sidewall portion 10, the difference in rigidity is large between the inner region and the outer region in the tire radial direction with the carcass end portion 36 as a base point, and even when the reinforcing layer 40 is not provided, the bead portion 20 side is provided. The rigidity is high. As described above, when the reinforcing layer 40 is provided so as to overlap the turn-up portion 35 when the reinforcing layer 40 is provided on the sidewall portion 10 having the rigidity difference with the carcass end portion 36 as a base point, The rigidity is further increased.

  On the other hand, in the pneumatic tire 1 according to the present embodiment, the reinforcing layer 40 is not overlapped with the turn-up portion 35 but is spaced apart from the carcass end portion 36 of the turn-up portion 35 toward the outer side in the tire radial direction. Therefore, the rigidity of the sidewall portion 10 can be gradually reduced in the region where the turn-up portion 35 is located, the region where the reinforcing layer 40 is disposed, and the region where the reinforcing layer 40 is not disposed. That is, the rigidity of the sidewall portion 10 can be gradually reduced from the inner side in the tire radial direction toward the outer side in the tire radial direction, and due to the provision of the reinforcing layer 40, the vicinity of the bead portion 20 Only the rigidity of the bead 20 can be suppressed, and the rigidity of the bead portion 20 can be suppressed from becoming too high. The reinforcing layer 40 also has a function as a rigidity reducing layer for reducing the rigidity difference with the carcass end portion 36 as a base point in this way. By providing the reinforcing layer 40, the carcass end portion 36 is used as a base point. It is possible to alleviate the difference in rigidity and to prevent the rigidity of the bead portion 20 from becoming too high. Thereby, the fall of rim assembly property can be suppressed.

  Furthermore, since the reinforcement layer 40 includes a rubber whose modulus at 100% elongation is 120% or more and 250% or less of the side rubber 11 constituting the sidewall portion 10, the reinforcement layer 40 is disposed. The rigidity of the part which is provided can be made to be the rigidity between the part where the turn-up part 35 is disposed and the part where the turn-up part 35 and the reinforcing layer 40 are not disposed. Thereby, it can suppress more reliably that only the rigidity of the bead part 20 vicinity becomes high resulting from providing the reinforcement layer 40, and can suppress the fall | rim assembly property fall more reliably. As a result, weight reduction can be achieved without causing a step on the tire surface 12 without deteriorating rim assembly.

  Further, since the reinforcing layer 40 is separated from the carcass end portion 36 within the range where the distance S between the reinforcing layer lower end portion 42 and the carcass end portion 36 is 5 mm or more and 20 mm or less, the turnup in the sidewall portion 10 is performed. The change in rigidity from the position where the portion 35 is disposed to the position where the reinforcing layer 40 is disposed can be made gentle. Thereby, since it is not necessary to make up with the side rubber 11 the rigidity difference in the side wall part 10 from the carcass end part 36 as a base point, the rubber gauge Ga of the side wall part 10 can be made thinner. As a result, the weight can be more reliably reduced.

  Further, in the reinforcing layer 40, the relationship between the reinforcing layer upper end height HM and the shoulder edge height HE when the carcass end portion 36 is used as a reference satisfies the position {(HM / HE) ≦ 0.6}. Since the reinforcing layer upper end portion 41 is disposed, the rigidity relaxation effect by the reinforcing layer 40 can be obtained more reliably. That is, when the reinforcing layer upper end 41 is located at a position where the reinforcing layer upper end height HM and the shoulder edge height HE are {(HM / HE)> 0.6}, the reinforcing layer 40 is disposed. Therefore, the rigidity of the region other than the region where the turn-up portion 35 is provided in the sidewall portion 10 may become too high. In this case, it becomes difficult to obtain the rigidity relaxation effect by the reinforcing layer 40, and the rigidity of the entire sidewall portion 10 becomes high, so that it may be difficult to effectively reduce the rim assembly property.

  On the other hand, in the pneumatic tire 1 according to the present embodiment, the reinforcing layer upper end height HM and the shoulder edge height HE satisfy the {(HM / HE) ≦ 0.6}. Since the portion 41 is arranged so as to be positioned, the rigidity of the sidewall portion 10 can be gradually reduced from the inner side in the tire radial direction toward the outer side in the tire radial direction. Thereby, since the rigidity relaxation effect by the reinforcement layer 40 can be acquired more reliably, weight reduction can be achieved more reliably without deteriorating rim assemblability.

  Further, since the reinforcing layer 40 is provided as an organic fiber reinforcing layer having a reinforcing layer cord 45 that is an organic fiber member and rubber, the rigidity of the reinforcing layer 40 can be appropriately ensured, and the carcass end portion 36 can be secured. The difference in rigidity from the base point can be more reliably mitigated. As a result, the weight can be reduced more reliably without deteriorating the rim assembly.

  In the reinforcing layer 40, the cord diameter DM of the reinforcing layer cord 45 and the cord diameter DC of the carcass cord 38 satisfy the relationship {0.6 ≦ (DM / DC) ≦ 0.9}. The rigidity relaxation effect by the reinforcing layer 40 can be obtained more reliably. That is, when the cord diameter DM of the reinforcing layer cord 45 and the cord diameter DC of the carcass cord 38 are {(DM / DC) <0.6}, the cord diameter DM of the reinforcing layer cord 45 is too small. Therefore, it may be difficult to ensure the rigidity of the reinforcing layer 40. In this case, it may be difficult to effectively mitigate the difference in rigidity with the carcass end 36 as a base point by the reinforcing layer 40. When the cord diameter DM of the reinforcing layer cord 45 and the cord diameter DC of the carcass cord 38 are {(DM / DC)> 0.9}, the cord diameter DM of the reinforcing layer cord 45 is too large. Therefore, the rigidity of the reinforcing layer 40 may become too high. In this case, the rigidity of the portion where the reinforcing layer 40 is disposed becomes too high, and a rigidity difference with the reinforcing layer upper end 41 as a base point may occur.

  On the other hand, in the pneumatic tire 1 according to the present embodiment, the cord diameter DM of the reinforcing layer cord 45 and the cord diameter DC of the carcass cord 38 satisfy {0.6 ≦ (DM / DC) ≦ 0.9}. In order to satisfy the relationship, the rigidity of the reinforcing layer 40 can be brought close to an intermediate characteristic between the region where the turn-up portion 35 is not provided in the sidewall portion 10 and the region where the carcass end portion 36 is located. As a result, the rigidity difference with the carcass end portion 36 as the base point can be more reliably mitigated by the reinforcing layer 40, and the weight can be reduced more reliably without deteriorating the rim assembly property.

  In the reinforcing layer 40, the cord angle AM of the reinforcing layer cord 45 with respect to the tire circumferential direction and the cord angle AC with respect to the tire circumferential direction of the carcass cord 38 in the turn-up portion 35 of the carcass layer 30 are {−20 ° ≦ (AC− AM) ≦ −5 °}, the rigidity relaxation effect by the reinforcing layer 40 can be obtained more reliably. That is, when the cord angle AM of the reinforcing layer cord 45 with respect to the tire circumferential direction and the cord angle AC of the carcass cord 38 are {(AC−AM) <− 20 °}, the cord angle AM of the reinforcing layer cord 45. However, since the inclination of the carcass cord 38 may be excessively inclined with respect to the cord angle AC, the rigidity of the reinforcing layer 40 may be too small relative to the rigidity of the turn-up portion 35 of the carcass layer 30. In this case, it may be difficult to effectively mitigate the difference in rigidity with the carcass end 36 as a base point by the reinforcing layer 40. When the cord angle AM of the reinforcing layer cord 45 with respect to the tire circumferential direction and the cord angle AC of the carcass cord 38 are {(AC−AM)> − 5 °}, the cord angle AM of the reinforcing layer cord 45 is And the cord angle AC of the carcass cord 38 may be too small, it may be difficult to reduce the rigidity of the reinforcing layer 40 relative to the rigidity of the turn-up portion 35 of the carcass layer 30. In this case, the rigidity of the portion where the reinforcing layer 40 is disposed becomes too high, and a rigidity difference with the reinforcing layer upper end 41 as a base point may occur.

  In contrast, in the pneumatic tire 1 according to the present embodiment, the cord angle AM of the reinforcing layer cord 45 and the cord angle AC of the carcass cord 38 with respect to the tire circumferential direction are {−20 ° ≦ (AC−AM) ≦ −. 5 °}, the rigidity of the reinforcing layer 40 can be brought close to an intermediate characteristic between the region where the turn-up portion 35 is not provided in the sidewall portion 10 and the region where the carcass end portion 36 is located. . As a result, the rigidity difference with the carcass end portion 36 as the base point can be more reliably mitigated by the reinforcing layer 40, and the weight can be reduced more reliably without deteriorating the rim assembly property.

  Further, since the density EM of the reinforcing layer cord 45 and the density EC of the carcass cord 38 satisfy the relationship {0.65 ≦ (EM / EC) ≦ 0.95}, the reinforcing layer 40 has a reinforcing layer. The rigidity relaxation effect by 40 can be obtained more reliably. That is, when the density EM of the reinforcing layer cord 45 and the density EC of the carcass cord 38 are {(EM / EC) <0.65}, the density EM of the reinforcing layer cord 45 may be too small. In some cases, it is difficult to ensure the rigidity of the reinforcing layer 40. In this case, it may be difficult to effectively mitigate the difference in rigidity with the carcass end 36 as a base point by the reinforcing layer 40. Further, when the density EM of the reinforcing layer cord 45 and the density EC of the carcass cord 38 are {(EM / EC)> 0.95}, the density EM of the reinforcing layer cord 45 may be too large. The rigidity of the reinforcing layer 40 may become too high. In this case, the rigidity of the portion where the reinforcing layer 40 is disposed becomes too high, and a rigidity difference with the reinforcing layer upper end 41 as a base point may occur.

  On the other hand, in the pneumatic tire 1 according to this embodiment, the density EM of the reinforcing layer cord 45 and the density EC of the carcass cord 38 have a relationship of {0.65 ≦ (EM / EC) ≦ 0.95}. In order to satisfy, the rigidity of the reinforcing layer 40 can be brought close to an intermediate characteristic between the region where the turn-up portion 35 is not provided in the sidewall portion 10 and the region where the carcass end portion 36 is located. As a result, the rigidity difference with the carcass end portion 36 as the base point can be more reliably mitigated by the reinforcing layer 40, and the weight can be reduced more reliably without deteriorating the rim assembly property.

  Moreover, since the pneumatic tire 1 according to the present embodiment is a temporary tire that is used as an emergency when a pneumatic tire mounted on the vehicle fails, the pneumatic tire 1 can be applied to the vehicle by reducing the weight. It is possible to improve fuel efficiency and driving performance when the vehicle is driven in the mounted state. Moreover, since it can suppress that a level | step difference generate | occur | produces in the tire surface 12 in the part of the carcass end part 36 of the turnup part 35, an external appearance can be improved. In addition, since the difference in rigidity with the carcass end portion 36 as a base point is alleviated by the reinforcing layer 40, rim assemblability can be ensured even in a temporary tire.

〔Example〕
FIG. 7A, FIG. 7B, and FIG. 7C are charts showing the results of performance tests of pneumatic tires. Hereinafter, the performance evaluation test performed on the pneumatic tire 1 of the conventional example and the comparative example and the pneumatic tire 1 according to the present invention will be described. In the performance evaluation test, an evaluation test on the state of occurrence of a step on the tire surface 12 of the sidewall portion 10, an evaluation test on the rim assembly property, and a thickness of the side rubber 11 serving as an index of weight reduction of the pneumatic tire 1. An evaluation test for Ga was performed.

  These performance evaluation tests were performed using a pneumatic tire 1 having a tire size specified by JATMA and having a T155 / 90D17 size. The evaluation method for each test item is as follows. For the step of the sidewall portion 10, the pneumatic tire 1 to be evaluated is assembled on a rim wheel of a 17 × 4T size JATMA standard rim, and inflated to 420 kPa for 24 hours. After leaving indoors, the presence or absence of a step in the sidewall portion 10 was visually determined. As for rim assembly, the pneumatic tire 1 to be evaluated is assembled to a rim wheel of a JATMA standard rim by an automatic rim assembly machine, and the bead portions 20 on both sides in the tire width direction are dropped into the rim without any problem. This was done by indexing the work yield. The rim assemblability is displayed with a score of 100 as a conventional example, which will be described later, and those having an index of 99 or more are determined to be good for the rim assemblability. Moreover, about the thickness Ga of the side rubber 11, it carried out by indexing the thickness Ga of the side rubber 11 in the position of the carcass edge part 36 of the pneumatic tire 1 which performs an evaluation test. The thickness Ga of the side rubber 11 is displayed as a score with a conventional example described later as 100, and those having an index of 90 or less are determined to be effective in reducing the weight.

  The evaluation tests were performed on 16 types of pneumatic tires according to Examples 1 to 13 which are the conventional examples 1 and 2 and the pneumatic tires 1 according to the present invention. 1 was performed. These pneumatic tires 1 are different in the presence or absence of the reinforcing layer 40 and the form of the reinforcing layer 40. Among these, the pneumatic tires 1 of the conventional examples 1 and 2 are not provided with the reinforcing layer 40. In the pneumatic tire 1 of the comparative example, although the reinforcing layer 40 is provided, the reinforcing layer 40 is not separated from the turn-up portion 35 of the carcass layer 30, and a part thereof overlaps the turn-up portion 35. Arranged. That is, the reinforcing layer 40 has the reinforcing layer lower end portion 42 positioned on the inner side in the tire radial direction of the carcass end portion 36, and the vicinity of the reinforcing layer lower end portion 42 overlaps the carcass end portion 36 vicinity of the turn-up portion 35. Yes.

  On the other hand, Examples 1-13 which are examples of the pneumatic tire 1 which concerns on this invention have all the reinforcement layers 40, and all the reinforcement layers 40 are the tire radial direction outer sides of the carcass edge part 36. It is arranged. Further, the reinforcing layer 40 has a distance from the carcass end portion 36, a position of the reinforcing layer upper end portion 41, a cord diameter DC of the carcass cord 38, a cord angle AC, a cord diameter DM of the reinforcing layer cord 45 with respect to the density EC, and a cord angle AM. The densities EM are different from each other.

  As a result of performing an evaluation test using these pneumatic tires 1, as shown in FIGS. 7A, 7 </ b> B, and 7 </ b> C, the pneumatic tires 1 of Examples 1 to 13 are the On the other hand, it has been found that the thickness Ga of the side rubber 11 can be reduced without causing a step in the sidewall portion 10 and without lowering the rim assembly property, and the weight can be reduced. That is, the pneumatic tires 1 of Examples 1 to 13 can be reduced in weight without causing a step on the tire surface 12 without deteriorating rim assembly.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Tread surface 4 Shoulder part 5 Shoulder edge 6 Breaker 10 Side wall part 11 Side rubber 12 Tire surface 20 Bead part 21 Bead core 24 Bead filler 25 Bead filler end part 30 Carcass layer 31 Carcass 34 Carcass main body part 35 Turn-up portion 36 Carcass end portion 38 Carcass cord 40 Reinforcing layer 41 Reinforcing layer upper end portion 42 Reinforcing layer lower end portion 45 Reinforcing layer cord (organic fiber member)

Claims (7)

A tread portion having a tread surface;
Sidewall portions disposed from both ends of the tread portion in the tire width direction toward the inside in the tire radial direction;
A bead portion disposed on a tire radial direction side of the sidewall portion;
A bead core provided in the bead portion;
A bead filler disposed on the outer side in the tire radial direction of the bead core;
The bead on the both sides of the tire width direction is composed of a plurality of carcasses in which a carcass cord is inclined at an angle of 20 ° to 50 ° with respect to the tire circumferential direction and the carcass cord is arranged to intersect with each other. A carcass layer disposed between the parts and folded around the bead core;
With
In the carcass layer, a carcass end portion that is an end portion on the outer side in the tire radial direction in the turn-up portion that is a folded portion is located on the inner side in the tire width direction with respect to the turn-up portion in the carcass layer. Touching the part,
A tire cross-section height HS which is a distance in a tire radial direction between a portion located on the outermost side in the tire radial direction in the tread portion and a rim baseline;
A bead filler height HB which is a distance in the tire radial direction between an end portion on the outer side in the tire radial direction of the bead filler and the rim base line;
A carcass end height HC which is a distance in a tire radial direction between the carcass end and the rim base line;
Is a relationship satisfying {(HB / HS) <0.25} and {0.25 <(HC / HS) <0.5},
The outer side in the tire radial direction of the carcass end portion includes a rubber whose modulus at 100% elongation is 120% or more and 250% or less of the rubber constituting the sidewall portion, and along the carcass layer. A pneumatic tire characterized by being provided with a reinforcing layer that is spaced apart from the carcass end. The reinforcing layer has a distance between the lower end in the tire radial direction and the end of the carcass of 5 mm to 20 mm, and
Reinforcement layer upper end height HM that is a distance in the tire radial direction between the upper end portion of the reinforcement layer that is an end portion on the outer side in the tire radial direction of the reinforcement layer and the carcass end portion;
A shoulder edge height HE which is a distance in a tire radial direction between a shoulder edge located at both ends of the tread portion in the tire width direction and the carcass end portion;
The pneumatic tire according to claim 1, wherein the upper end portion of the reinforcing layer is located at a position satisfying {(HM / HE) ≦ 0.6}.   The pneumatic tire according to claim 1, wherein the reinforcing layer is an organic fiber reinforcing layer having an organic fiber member.   4. The reinforcing layer according to claim 3, wherein the cord diameter DM of the organic fiber member and the cord diameter DC of the carcass cord satisfy a relationship of {0.6 ≦ (DM / DC) ≦ 0.9}. Pneumatic tire.   In the reinforcing layer, a cord angle AM of the organic fiber member with respect to the tire circumferential direction and a cord angle AC with respect to the tire circumferential direction of the carcass cord in the turn-up portion of the carcass layer are {−20 ° ≦ (AC− The pneumatic tire according to claim 3 or 4, satisfying a relationship of (AM) ≤ -5 °}.   6. The reinforcing layer according to claim 3, wherein the density EM of the organic fiber member and the density EC of the carcass cord satisfy a relationship of {0.65 ≦ (EM / EC) ≦ 0.95}. The pneumatic tire according to item 1.   The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is a temporary tire used as an emergency when a pneumatic tire mounted on a vehicle fails.

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