JP2015016766A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pneumatic tire capable of effectively reinforcing a carcass cord while suppressing increase in a tire weight.SOLUTION: When a distance between a first vertical line VL1 passing the center of a bead core 18 and a second vertical line VL2 passing a tire maximum width end P, measured in a state of folding up intervals between a bead part 12, a tire side part 14 and a tread part 16 between a rim flange 42 and a step part 40 by loading a weight in a state of mounting on a rim 38 is defined as L, a radial direction outer reinforcement layer 34 and a radial direction inner reinforcement layer 36 of a dimension of 0.58-0.62 L are arranged from the first vertical line VL1 to the second vertical line VL2, along a carcass ply 20 so as to reinforce a carcass cord.

Description

  The present invention relates to a pneumatic tire, and relates to a pneumatic tire that can reinforce a carcass cord and ensure durability while suppressing an increase in tire weight.

  If the tire buckles between the rim flange and the curb during the curb ride, the carcass cord may receive a large compressive force in the shear direction. In view of this, a technique based on the idea of providing a cushion rubber body on the tire inner surface and absorbing and mitigating impact with the cushion rubber body when the tire rides on the curb and the tire inner surfaces contact each other has been proposed (for example, Patent Document 1). reference).

Japanese Patent Application Laid-Open No. 2008-290540.

However, the above prior art provides a cushion rubber body that absorbs and relaxes the impact when the curb rides over a relatively wide range of the buttress area on the tire lumen side and the bead area, so that the durability of the carcass cord is improved. If the friction rubber body is made thicker for improvement, the tire weight will further increase.
It is also possible to improve the durability of the carcass cord by increasing the number of carcass and the number of driven carcass cords on the side of the tire, but the tire weight increases, and the vertical spring constant of the tire increases. The comfort gets worse.

  In view of the above facts, the present invention has an object to provide a pneumatic tire that can reinforce a carcass cord and improve durability while suppressing an increase in tire weight.

  The invention according to claim 1 includes a plurality of carcass cords, a carcass ply formed in a toroidal shape across a pair of bead cores, and a tread portion disposed on the outer side in the tire radial direction of the carcass ply. A tire side portion disposed between the tread portion and the bead core and disposed on the outer side in the tire width direction of the carcass ply, and disposed along the carcass ply on the inner side in the tire width direction from the tire side portion. In a pneumatic tire having a reinforcing material, the pneumatic tire is pressed against a step portion formed higher than a road surface on which the pneumatic tire is grounded in a state where the pneumatic tire is mounted on a standard rim and a prescribed internal pressure is applied. By folding back at the tire maximum width position, another tire facing the tire inner surface from the tire maximum width position to the bead core is opposed. When in contact with the inner surface, the reinforcing member is on a vertical line passing through the center of the bead core with respect to a horizontal distance L from the center of the bead core to the maximum tire width, and the other end is 0.58. It is arranged at a position of ~ 0.62L.

The pneumatic tire according to claim 1 has one end on a vertical line passing through the center of the bead core and the other end of 0.58 to 0, where L is a horizontal distance from the center of the bead core to the maximum tire width. Reinforcing material disposed at a position of .62L is provided.
For this reason, when the bead part, the tire side part, and the tread part are sandwiched between the rim and the step part and are deformed to protrude outward in the tire width direction, the compressive force in the shear direction from the rim and the step part Can improve the rigidity within the range of 0.58 to 0.62 L from the vertical line passing through the center of the bead core to the outside in the tire axial direction, and the carcass cord can be reinforced.

Since the carcass cord is susceptible to a compressive force in the shear direction within a range of 0.58 to 0.62 L from the vertical line passing through the center of the bead core to the outer side in the tire axial direction, the horizontal length of the reinforcing material is 0.58 to 0.62 L from the vertical line passing through the center outward in the tire axial direction is sufficient for reinforcing the carcass cord. If the length of the reinforcing material is longer than the above range, the reinforcing material will be used unnecessarily, and the longitudinal spring constant of the tire will increase and the riding comfort will deteriorate, or the weight of the tire will increase. On the other hand, if the length of the reinforcing material is shorter than the above range, it is insufficient for reinforcing the carcass cord.
Further, in the pneumatic tire according to claim 1, since the number of carcass and the number of driven carcass cords are not increased in order to reinforce the carcass cord, the tire weight is not increased.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, in the tire radial direction outer portion of the portion where the bead portion, the tire side portion, and the tread portion are folded over. A radially outer reinforcing material disposed on a radially inner reinforcing material disposed on a tire radial inner portion of a folded portion of the bead portion, the tire side portion, and the tread portion. It is configured.

When the bead part, the tire side part, and the tread part are sandwiched between the rim and the step part and folded and protruded outward in the tire width direction, the carcass cord is bent along with the tire deformation. The two portions, the outer portion in the tire radial direction and the inner portion in the tire radial direction of the folded portion, are sandwiched between the rim and the stepped portion.
In the pneumatic tire according to claim 2, the carcass cord disposed in the outer portion in the tire radial direction of the folded portion is suppressed by the radially outer reinforcing material, and the carcass cord on the inner side in the tire radial direction of the folded portion is Suppressed by the radially inner reinforcement.

  According to a third aspect of the present invention, in the pneumatic tire according to the second aspect, when the tire flatness is 55% or less, the rigidity of the radially inner reinforcing member is set to be the rigidity of the radially outer reinforcing member. Set higher than.

In the case of a pneumatic tire having a flatness ratio of 55% or less, the carcass cord on the inner side in the tire radial direction from the end of the maximum width of the tire is more sheared than the carcass cord on the outer side of the maximum width of the tire in the radial direction of the tire. It tends to be subject to compressive force.
For this reason, in the case of a pneumatic tire having a flatness ratio of 55% or less, it is preferable to set the rigidity of the radially inner reinforcing material higher than the rigidity of the radially outer reinforcing material.

  According to a fourth aspect of the present invention, in the pneumatic tire according to the second aspect, when the tire flatness is 60% or more, the rigidity of the radially outer reinforcing material is set to be the rigidity of the radially inner reinforcing material. Set higher than.

In the case of a pneumatic tire having a flatness ratio of 60% or more, the carcass cord on the outer side in the tire radial direction is closer to the shear direction than the carcass cord on the inner side in the tire radial direction than the tire maximum width end. It tends to be subject to compressive force.
For this reason, in the case of a pneumatic tire having a flatness ratio of 60% or more, it is preferable to set the rigidity of the radially outer reinforcing material higher than the rigidity of the radially inner reinforcing material.

  According to a fifth aspect of the present invention, in the pneumatic tire according to the third or fourth aspect, a difference in rigidity between the rigidity of the radially outer reinforcing material and the rigidity of the radially inner reinforcing material is 30% or more. It is.

  As in the pneumatic tire according to claim 3 or 4, when the difference between the rigidity of the radially outer reinforcing member and the rigidity of the radially inner reinforcing member is set, the difference in rigidity is set to 30% or more. Corresponding to the flatness of the pneumatic tire, the reinforcing effect of the carcass cord becomes more reliable.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the reinforcing material is provided in close contact with an outer surface or an inner surface of the carcass ply.

By providing the reinforcing material in close contact with the outer surface or inner surface of the carcass ply, the reinforcement of the carcass cord is effectively enhanced.
By arranging the reinforcing material on the outer surface of the carcass ply, the reinforcing material is arranged on the input side of the compressive force, so that the reinforcing material receives the compressive force from the step portion and the rim before the carcass cord. The carcass cord can be reinforced more effectively.

  The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing material includes an organic fiber cord.

  Since the organic fiber cord contained in the reinforcing material has higher rigidity than the rubber constituting the tire, the carcass cord can be effectively reinforced.

  The invention according to claim 8 is the pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing material is formed of rubber harder than the side rubber forming the tire side portion.

  Since the reinforcing material is formed of rubber harder than the side rubber forming the tire side portion, the carcass cord can be effectively suppressed.

  The method for setting a reinforcing material for a pneumatic tire according to claim 9 is provided by installing a reinforcing material for a pneumatic tire including a plurality of carcass cords and having a carcass ply extending from one bead core to the other bead core. The tread portion is mounted on the rim and loaded with a load, and the tread portion is placed on the step portion provided higher than the road surface on which the pneumatic tire contacts the ground so that the bead core is positioned above the step portion. And a first vertical line passing through the center of the bead core in a state where the bead portion, the tire side portion, and the red portion are sandwiched between the stepped portion and the stepped portion, and are deformed so as to protrude outward in the tire width direction. When the horizontal distance from the second vertical line passing through the tire maximum width end is L, the horizontal length from the first vertical line to the second vertical line is 0.58-0. Set to 62L Placing a reinforcing member for performing reinforcement of the carcass cord.

In the method for setting a reinforcing material for a pneumatic tire according to claim 9, first, a load is applied in a state where the pneumatic tire is mounted on the rim, and the bead portion, the tire side portion, and the red portion are connected to the rim and the step portion. And is folded so as to protrude outward in the tire width direction.
Then, in a state where the bead portion, the tire side portion, and the tread portion are sandwiched between the rim and the stepped portion and folded so as to protrude outward in the tire width direction, the first vertical line to the second vertical The length in the horizontal direction toward the line is set to 0.58 to 0.62 L, the outer radial reinforcing material is arranged on the outer side in the tire radial direction to reinforce the carcass cord, and the carcass is arranged on the inner side in the tire radial direction. A radially inner reinforcing material for reinforcing the cord is arranged.

  Since the carcass cord is susceptible to a compressive force in the shear direction within a range from 0.58 to 0.62 L from the first vertical line to the second vertical line, the carcass cord is within the range from the first vertical line. If the radially outer reinforcing member and the radially inner reinforcing member whose horizontal length is set to 0.58 to 0.62 L toward the second vertical line are arranged, the compressive force in the shearing direction is increased. A pneumatic tire in which the carcass is reinforced can be obtained without increasing the tire weight unnecessarily by improving the rigidity within a range easily received.

  The pneumatic tire according to claim 10 includes a pair of bead portions, a tire side portion continuous to the outside in the tire radial direction of the bead portion, a tread portion straddling one tire side portion and the other tire side portion, and a plurality of tires. A carcass ply including a carcass cord and extending from a bead core embedded in one of the bead portions to a bead core embedded in the other bead core, and a belt layer disposed on the outer side in the tire radial direction of the carcass ply A radially outer reinforcing material that is arranged along the carcass ply from the end of the belt layer toward the tire equatorial plane side and the tire side portion side, and that reinforces the carcass cord, and the radially outer reinforcing material The carcass as viewed in a cross section along the tire rotation axis, extending from the bead core side toward the tire side portion side. Having a radially inner stiffener performing reinforcement of the carcass cord has a length identical to the length of the radially outer reinforcing member along the line.

In the pneumatic tire according to claim 10, a deformation that rides on a protrusion such as a curb and the bead portion, a tire side portion, and a tread portion are sandwiched between a rim and a protrusion such as a curb and protrudes outward in the tire width direction. Since the rigidity of the portion where the compressive force in the shearing direction from the rim and the protrusion acts can be increased by the presence of the radially outer reinforcing material and the radially inner reinforcing material, the carcass cord is reinforced. be able to.
Since the radially outer reinforcing material is disposed along the carcass ply toward the tire equatorial plane side and the tire side portion side with the end of the belt layer as the center, the rigidity of the portion where the radially outer reinforcing material is disposed Thus, the carcass ply at the portion where the radially outer reinforcing material is disposed can be reinforced.
On the other hand, since the radially inner reinforcing material is arranged along the carcass ply from the bead core side to the tire side portion side, the rigidity of the portion where the radially inner reinforcing material is arranged is improved, and the radially inner reinforcing material is provided. The carcass cord in the portion where the material is arranged can be reinforced.

  In the carcass, the part where the compressive force in the shearing direction from the rim and the protrusion acts is a deformation in which the bead part, the tire side part, and the tread part are sandwiched between the rim and the protrusion and protrude outward in the tire width direction. In the pneumatic tire according to claim 10, in the pneumatic tire according to claim 10, the carcass cord on the outer side in the tire radial direction and the carcass cord on the inner side in the tire radial direction in the tire radial direction are generated in the same region in the tire axial direction. The length and the length of the radially outer reinforcing material are the same. For this reason, the material usage-amount of a radial direction inner side reinforcement material and a radial direction outer side reinforcement material can be made into a required minimum, and the increase in a tire weight can be suppressed.

  The invention according to claim 11 is the pneumatic tire according to claim 10, wherein the length of the radially outer reinforcing material is L1, the length of the radially inner reinforcing material is L2, and the radially inner reinforcing material. L3 is the length from the tire radial inner end to the tire maximum width position of the carcass ply, and L3 is the length from the tire radial outer end of the radial outer reinforcement to the tire maximum width position of the carcass ply. L1 and L2 are 0.62 to 0.66L3.

  The length of the radially outer reinforcing material is L1, the length of the radially inner reinforcing material is L2, the length from the radially inner end of the radially inner reinforcing material to the tire maximum width position of the carcass ply is L3, When the length from the radially outer end of the radially outer reinforcing material to the maximum tire width position of the carcass ply is L3, the region that is susceptible to compressive force in the shearing force direction is the radial outer reinforcing material. Since the range from 0.62 to 0.66 L3 along the carcass ply from the tire radial direction outer end and the range from 0.62 to 0.66 L3 along the carcass ply from the tire radial direction inner end of the inner reinforcing layer, A radial outer reinforcing material and a radial inner reinforcing material having a length of 0.62 to 0.66L3 may be arranged in the range, and a radial outer reinforcing material and a radial inner reinforcing material longer than 0.66L3 are unnecessary.

  Thus, in the pneumatic tire according to the eleventh aspect, the material usage of the radially outer reinforcing material and the radially inner reinforcing material for reinforcing the carcass cord can be minimized.

In addition, when the length L1 of the radially outer reinforcing material and the length L2 of the radially inner reinforcing material are shorter than the above ranges, the effect of suppressing the carcass cord decreases.
On the other hand, when the length L1 of the radially outer reinforcing material and the length L2 of the radially inner reinforcing material are longer than the above range, the radially outer reinforcing material and the radially inner reinforcing material are used unnecessarily. As a result, the longitudinal spring constant of the tire increases and the riding comfort deteriorates, leading to an increase in the weight of the tire.

As described above, the pneumatic tire according to claim 1 has an excellent effect that the carcass cord can be reinforced while suppressing an increase in tire weight.
According to the pneumatic tire according to claim 2, the carcass cord disposed in the outer portion in the tire radial direction of the folded portion is reinforced by the radially outer reinforcing material, and the inner portion in the tire radial direction of the folded portion. The carcass cord is reinforced by the radially inner reinforcing material.
According to the pneumatic tire of the third aspect, in a pneumatic tire having an aspect ratio of 55% or less, it is possible to effectively reinforce a portion of the carcass cord in which the compressive force in the shearing direction acts greatly.
According to the pneumatic tire of the fourth aspect, in a pneumatic tire having an aspect ratio of 60% or more, it is possible to effectively reinforce a portion of the carcass cord in which the compressive force in the shearing direction acts greatly.
According to the pneumatic tire of the fifth aspect, the carcass cord can be effectively reinforced corresponding to the flatness of the tire.
According to the pneumatic tire of the sixth aspect, the reinforcement of the carcass cord can be more effectively suppressed.
According to the pneumatic tire of claim 7, it is possible to more effectively suppress the reinforcement of the carcass cord with a simple configuration in which the organic fiber cord is included in the radially outer reinforcing material and the radially inner reinforcing material. it can.
According to the pneumatic tire of the eighth aspect, the reinforcement of the carcass cord is more effectively suppressed with a simple configuration in which the radially outer reinforcing material and the radially inner reinforcing material are formed from rubber harder than the side rubber. be able to.
According to the method for setting a reinforcing material for a pneumatic tire according to claim 9, the carcass cord can be reinforced while suppressing an increase in tire weight.
The pneumatic tire according to claim 10 has an excellent effect that the carcass cord can be reinforced while suppressing an increase in the tire weight.
According to the pneumatic tire of the eleventh aspect, the material usage of the radially outer reinforcing material and the radially inner reinforcing material can be minimized.

1 is a cross-sectional view along a tire axis showing a state in which a pneumatic tire according to an embodiment of the present invention is mounted on a rim. It is sectional drawing of the carcass ply used for the pneumatic tire which concerns on one Embodiment of this invention. It is sectional drawing of the radial direction outer side reinforcement material used for the pneumatic tire which concerns on one Embodiment of this invention. 1 is a cross-sectional view along a tire axis showing a state when a pneumatic tire according to an embodiment of the present invention rides on a stepped portion. It is sectional drawing along the tire axis line which shows the state which mounted | wore the rim with the pneumatic tire which concerns on the modification of this invention.

A pneumatic tire 10 according to an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the pneumatic tire 10 of the present embodiment is for a passenger car, and a pair of bead portions 12, a tire side portion 14 continuous with the bead portion 12, and both tire side portions via a shoulder portion 15. 14 and a tread portion 16 straddling 14.
A bead core 18 is embedded in each bead portion 12, and a carcass 22 including a single carcass ply 20 extends from one bead core 18 to the other bead core 18 in this embodiment. The carcass 22 may be composed of two or more carcass plies 20.

As shown in FIG. 2, the carcass ply 20 of the present embodiment has a configuration in which carcass cords 21A made of a plurality of organic fibers are arranged in parallel with each other and coated with rubber 21B, like the carcass ply of a general pneumatic tire. is there. In addition, although the organic fiber used for the carcass cord 21A of the present embodiment is rayon, the carcass cord 21A may be another organic fiber generally used as a tire carcass cord.
As shown in FIG. 1, the carcass ply 20 includes a main body portion 20A extending from one bead core 18 to the other bead core 18 and a folded portion 20B that folds the bead core 18 from the inner side to the outer side in the tire radial direction (arrow A direction). Have.
A bead filler 24 extending from the bead core 18 toward the outer side in the tire radial direction is provided between the main body portion 20A and the folded portion 20B. The bead filler 24 gradually decreases in thickness toward the outer side in the tire radial direction.
A side rubber 26 constituting an outer surface side of the tire side portion 14 and the bead portion 12 is disposed on the outer side in the tire radial direction of the folded portion 20B of the carcass ply 20, the bead filler 24, and the main body portion 20A of the carcass ply.
Further, a belt 28 is disposed on the outer side in the tire radial direction of the carcass ply 20, and a tread rubber 30 constituting the tread portion 16 is disposed on the outer side in the tire radial direction of the belt 28.
A main groove 31 for drainage is formed in the tread portion 16.

In the vicinity of the shoulder portion 15 of the pneumatic tire 10 of the present embodiment, a radially outer reinforcing layer 34 is provided in close contact with the outer surface of the main body portion 20A along the main body portion 20A of the carcass ply 20. In addition, the radial direction outer side reinforcement layer 34 of this embodiment is arrange | positioned from the edge part of the belt 28 toward the tire equatorial plane CL side and the tire side part 14 side.
Further, in the vicinity of the bead portion 12, the radially inner reinforcing layer 36 is in close contact with the outer surface of the main body portion 20 </ b> A along the main body portion 20 </ b> A of the carcass ply 20 and extends from the bead core 18 side toward the tire side portion 14 side. Is provided.
Further, the radially inner reinforcing layer 36 of the present embodiment is disposed between the main body portion 20 </ b> A and the bead filler 24, and is in close contact with the bead filler 24.
As shown in FIG. 3, the radially outer reinforcing layer 34 of the present embodiment is a ply-like structure in which a plurality of organic fiber cords 35A are arranged in parallel with each other and coated with rubber 35B. Although illustration is omitted, the radially inner reinforcing layer 36 has the same configuration as the radially outer reinforcing layer 34. Although the nylon cord is used as the organic fiber cord 35A in the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 of the present embodiment, a cord made of a material other than nylon may be used.

Below, the position in which the radial direction outer side reinforcement layer 34 and the radial direction inner side reinforcement layer 36 are provided is demonstrated in detail.
As shown in FIG. 4, the pneumatic tire 10 is mounted on the rim 38, and the pneumatic tire 10 contacts the tread portion 16 on one side of the pneumatic tire 10 with the tire rotating shaft horizontal. The upper surface 40A that is more convex than the road surface 41 rides on the stepped portion 40 that is leveled, and a load is applied to the pneumatic tire 10 via the rim 38, and the bead portion 12, the tire side portion 14, and the tread portion 16 are loaded. The space between the rim 38 and the step portion 40 is folded between the portion of the rim 38 where the bead portion 12 is in contact (hereinafter referred to as the vicinity of the rim flange 42) and deformed so as to protrude outward in the tire width direction. .
As shown in FIG. 4, the height H from the road surface 41 of the upper surface 40 </ b> A of the stepped portion 40 is sandwiched between the rim flange 42 and the stepped portion 40 between the bead portion 12 and the tread portion 16. Any dimension can be used as long as it can be folded and deformed so as to protrude outward in the tire width direction, and the dimension is not particularly limited.
When the bead portion 12 to the tread portion 16 are folded and sandwiched between the rim flange 42 and the step portion 40 and deformed so as to protrude outward in the tire width direction, the side surface 40B ( Measurement may be performed in a state in which the pneumatic tire 10 rides so that the tire equatorial plane CL is parallel to the front and back sides in FIG. 4, and the side surface of the step portion 40 (extends in the back and front directions in FIG. 4). ), The pneumatic tire 10 may be measured so that the tire equatorial plane CL has an angle.
As described above, when the space between the bead portion 12 and the tread portion 16 is deformed, the pneumatic tire 10 may be filled with air so as to have a specified internal pressure, and the air valve ( The internal pressure of the tire may be reduced from the specified internal pressure by removing the air from the tire (not shown) (the air pressure may be zero), and the air valve (not shown) may be removed from the rim 38 to reduce the internal pressure to zero ( That is, it may be in communication with the tire lumen and the atmosphere. Compared to the case where the pneumatic tire 10 is filled with the prescribed internal pressure, the interval between the bead portion 12 and the tread portion 16 is reduced when the internal pressure is reduced below the prescribed internal pressure or the air valve is removed from the rim 38. The load for deforming is small.

The rim and internal pressure here are standard rims (or "Approved Rim", "Recommended Rim") corresponding to the tire size specified in the standard, and the internal pressure is the application described in the following standard. Air pressure corresponding to the maximum load (maximum load capacity) of a single wheel in size. The standard is determined by an industrial standard effective in an area where the tire is produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Book”, in Europe “The European Tire and Rim Technical Organization Standards Manual”, and in Japan, the Japan Automobile Tire Association “JATMA Year Book”. ing.
And in the pneumatic tire 10 of this embodiment, as shown in FIG. 4, between the bead part 12 of one side and the tread part 16 is deform | transformed so that it may overlap between the rim flange 42 vicinity and the step part 40. A position where the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are arranged is defined in a state where the tire inner circumferential surface on the tire radial inner side and the tire inner circumferential surface on the tire radial outer side are in contact with each other.
Thus, when defining the positions where the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are disposed, at least the bead core 18 is positioned above the horizontal upper surface 40A of the stepped portion 40 as shown in FIG. The above rules are made in the state where
Thus, when the bead portion 12, the tire side portion 14, and the tread portion 16 are deformed so as to be folded between the vicinity of the rim flange 42 and the stepped portion 40, a radial direction is formed on the inner portion of the folded portion in the tire radial direction. The inner reinforcing layer 36 is disposed, and the radially outer reinforcing layer 34 is disposed in the tire radial direction outer portion of the folded portion.

Here, a first vertical line passing through the center of the bead core 18 (centroid in this embodiment) is VL1, and a second vertical line passing through the tire maximum width end P of the folded tire side portion 14 is VL2. .
When the distance measured in the horizontal direction (arrow B direction) between the first vertical line VL1 and the second vertical line VL2 is L, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are Both of the lengths measured in the horizontal direction from the first vertical line VL1 toward the outer side in the tire axial direction are set to 0.58 to 0.62L. In the present embodiment, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are set to the same length.

  In the unloaded state of the pneumatic tire 10 attached to the rim 38 and filled with the air pressure of the above standard, the radially inner end of the radially inner reinforcing layer 36 is the center of the bead core 18 as shown in FIG. It is located on the vertical line VL1 passing through (centroid). The length of the radially outer reinforcing layer 34 along the carcass ply 20 is L1, the length of the radially inner reinforcing layer 36 along the carcass ply 20 is L2, and the diameter of the carcass ply 20 from the tire maximum width position 20C is the diameter. When the length from the tire maximum width position 20C to the tire radial inner end of the radial inner reinforcing layer 36 is set to L3, the length along the carcass ply 20 to the tire radial outer end of the direction outer reinforcing layer 34 In addition, L1 and L2 are L1 = L2 and 0.62 to 0.66L3.

(Action)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
The tread portion 16 of the pneumatic tire 10 rides on the step portion 40, and as shown in FIG. 4, the gap between one bead portion 12 and the tread portion 16 is sandwiched between the vicinity of the rim flange 42 and the upper surface 40 </ b> A of the step portion 40. When the carcass cord 21 </ b> A (not shown in FIG. 4) of the main body 20 </ b> A is bent and is deformed to protrude outward in the tire width direction, the carcass cord 21 </ b> A is bent along with the deformation between the bead part 12 and the tread part 16. And is sandwiched between the vicinity of the rim flange 42 and the upper surface 40A of the stepped portion 40 at two locations, ie, a portion on the outer side in the tire radial direction and a portion on the inner side in the tire radial direction.

The compressive force in the shearing direction acting on the carcass cord 21A is likely to occur within a range from 0.58 to 0.62L from the first vertical line VL1 toward the second vertical line VL2. In the pneumatic tire 10 of the present embodiment, the radially outer reinforcing layer 34 and the radially inner reinforcing layer having a length of 0.58 to 0.62 L from the first vertical line VL1 toward the second vertical line VL2. 36 is arranged to increase the rigidity (shear rigidity in this embodiment) in the vicinity of the carcass cord 21A in the region that is easily subjected to the compressive force in the shear direction, so that the pneumatic tire 10 rides on the curb or the projection on the road surface. In this case, the carcass cord 21A in the region that is easily subjected to the compressive force in the shearing direction can be effectively reinforced with the minimum necessary material.
Since the carcass cord 21A is sandwiched between the rim flange 42 and the upper surface 40A of the stepped portion 40, two portions of the folded portion of the tire radial direction outer portion and the tire radial direction inner portion are sandwiched. The carcass cord 21A disposed at the outer portion in the tire radial direction of the folded portion is reinforced by the radially outer reinforcing layer 34, and the carcass cord 21A at the inner portion in the tire radial direction of the folded portion is the radially inner reinforcing layer. It is reinforced by 36.

  When the pneumatic tire 10 rides on the curb, the tire equatorial plane CL of the pneumatic tire 10 rides so as to be inclined (for example, 45 °) with respect to the longitudinal direction of the curb when the vehicle is viewed in plan. In some cases, the tire equatorial plane CL of the pneumatic tire 10 rides at a right angle to the longitudinal direction of the curb. The reinforcing effect of the carcass cord 21 by the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 of the pneumatic tire 10 according to the present embodiment is exhibited regardless of the above-described form of riding on the curb.

Here, when the lengths L1 and L2 in the horizontal direction from the first vertical line VL1 to the second vertical line VL2 of the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 become longer than the above range. In addition, the rigidity of the tire side portion 14 is increased, and the longitudinal spring constant of the pneumatic tire 10 is increased, leading to deterioration in riding comfort.
That is, in the pneumatic tire 10 according to the present embodiment, the radially outer reinforcing layer 34 having a high rigidity and the radially inner side in the vicinity of the maximum width 20C of the carcass 22 tire during normal time (see FIG. 1) having a great influence on the riding comfort. Since the reinforcing layer 36 is not disposed, a riding comfort equivalent to that of the conventional tire can be obtained during normal running.
On the other hand, when the lengths L1 and L2 in the horizontal direction from the first vertical line VL1 to the second vertical line VL2 of the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are shorter than the above range, The reinforcing effect of the carcass cord 21A is insufficient.

When the flatness of the pneumatic tire 10 is 55% or less, the carcass cord 21A on the inner side in the tire radial direction from the tire maximum width end P is closer to the carcass on the outer side in the tire radial direction than the tire maximum width end P. When the compression rate of the pneumatic tire 10 is more than 60%, the carcass cord 21A on the outer side in the tire radial direction from the tire maximum width end P is more likely to receive a compressive force in the shear direction than the cord 21A. The carcass cord 21A on the inner side in the tire radial direction than the tire maximum width end P tends to be more susceptible to a compressive force in the shearing direction.
Therefore, when the pneumatic tire 10 has a flatness ratio of 55% or less, it is preferable to set the rigidity of the radially inner reinforcing layer 36 higher than the rigidity of the radially outer reinforcing layer 34. When the rate is 60% or more, it is preferable to set the rigidity of the radially outer reinforcing layer 34 higher than the rigidity of the radially inner reinforcing layer 36.

As described above, when making a difference between the rigidity of the radially outer reinforcing layer 34 and the rigidity of the radially inner reinforcing layer 36, the flatness of the pneumatic tire 10 is to set the difference in rigidity to 30% or more. Accordingly, the reinforcing effect of the carcass cord 21A can be enhanced.
As an example, when nylon cords are used for the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36, a nylon cord having a strength of 194N is used for relatively high rigidity, and the rigidity is relatively low. Nylon cord having a strength of 131N can be used (the strength is about 32% different).
In addition, the reinforcing effect of the carcass cord 21A is further improved by making the organic fiber cord 35A used for the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 higher in shear rigidity than the carcass cord 21A. Can do.
Moreover, the direction which cross | intersects the organic fiber cord 35A of the radial direction outer side reinforcement layer 34 and the radial direction inner side reinforcement layer 36 with respect to the carcass cord 21A, and the radial direction outer side reinforcement layer 34 and diameter of the carcass cord 21A. The reinforcing effect of the carcass cord 21A can be enhanced as compared with the case where the organic fiber cords 35A of the direction-side reinforcing layer 36 are provided in parallel.

  In the above embodiment, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are provided so as to be in close contact with the outer surface of the carcass ply 20. However, as shown in FIG. The direction inner reinforcing layer 36 may be provided so as to be in close contact with the inner surface of the main body portion 20A of the carcass ply 20. Also in the present embodiment, the rigidity in the vicinity of the carcass cord 21 </ b> A arranged in the region that is easily subjected to the compressive force in the shear direction is enhanced by the presence of the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36. There is an effect to increase the effect.

  In the pneumatic tire 10 shown in FIGS. 1 and 5, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are configured to include an organic fiber cord, but the illustration is omitted. The radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 may be made of rubber harder than the side rubber 26.

  Also in the present embodiment, the rigidity in the vicinity of the carcass cord 21A disposed in the region that is easily subjected to the compressive force in the shear direction is increased by the presence of the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 made of hard rubber. The carcass cord 21A can be effectively reinforced with the minimum amount of material used.

[Test Example 1]
The inventors have developed various commonly used pneumatic tires for passenger cars that are not provided with a radially outer reinforcing layer and a radially inner reinforcing layer, and are generally used for a tire side portion damage testing machine ( As an example, it is attached to a device disclosed in Japanese Patent Application Laid-Open No. 2005-11459, and the load is increased until pinch cut occurs and air is released from the tire side portion, and the position where the pinch cut of the carcass cord occurs is determined. Examined. As shown in the test results in Table 1 below, it was found that a pinch cut of the carcass cord is likely to occur within a range from 0.58 to 0.62 L from the first vertical line to the second vertical line. .

The test was carried out with 10 tires for each tire size. The numerical values in Table 1 below represent the number of pinch cuts. “Outside” and “Inside” in the table indicate the positions where pinch cuts occurred, and “Outside” indicates the carcass ply on the outer side in the tire radial direction of the part where the bead portion, tire side portion, and tread portion are folded. It indicates that a pinch cut has occurred, and “inner” indicates that a pinch cut has occurred in the carcass ply on the inner side in the tire radial direction of the folded portion.
In the column of the occurrence position of pinch cuts in the table, “0” indicates the position of VL1 on the first vertical line. Further, “−0.1 L or more and less than 0” means a position on the tire equatorial plane side of the first vertical line from VL1.

From the test results, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 can be set and arranged at a length of 0.58 to 0.62 L from the first vertical line VL1 to the second vertical line VL2. It turns out that it is enough for the pinch cut countermeasure.
In addition, a pinch cut is likely to occur in the carcass inside the tire maximum width end in a tire with a flatness ratio of 55% or less, and a pinch cut in a carcass outside the tire maximum width end in a tire with a flatness ratio of 60% or more. I found a tendency to do it easily. Therefore, it is effective to make the rigidity of the radially inner reinforcing layer 36 higher than the rigidity of the radially outer reinforcing layer 34 in a tire having a flatness ratio of 55% or less, and in a tire having a flatness ratio of 60% or more, it is effective. It can be seen that it is effective to make the rigidity of the directional outer reinforcing layer 34 higher than that of the radially inner reinforcing layer 36.

[Test Example 2]
Attach a pneumatic tire of tire size 185 / 60R15 to the tire side damage tester, press the pneumatic tire 10 against the protrusion of the tire side damage tester with a load of 27 kN, and check the deformation of the tire side. In the deformed state, it was confirmed that the tire inner surfaces were in contact with each other in the range from the first vertical line VL1 passing through the center of the bead core to 0.6 L outward in the tire axial direction.

A radial outer reinforcing layer and a radial inner reinforcing layer made of rubber (thickness: 0.7 mm, hardness: 97 degrees in JIS K6523 type A, length: 0.6 L) are provided on the outer surface of the carcass ply of the present invention. Applied pneumatic tire of Example 1 (structure of the third embodiment), radially outer reinforcing layer including organic fiber cord (material PET. Strength: 151 N. Number of driven: 54. Length: 0 .6L) and the radially inner reinforcing layer (material PET. Strength: 151 N. Number of driving: 54. Length: 0.6 L) on the outer surface of the carcass ply of the pneumatic tire of Example 2 to which the present invention was applied ( The structure of the first embodiment), and three types of test tires, a pneumatic tire of a conventional example that does not include a radially outer reinforcing layer and a radially inner reinforcing layer, are prepared and used for a tire side damage tester. Install the test tire Kasukodo is destroyed tire side portion increases the load until the exit air pinch cut occurs, the measured maximum load during the period from a load to the air escapes. The value of the maximum load was as shown in Table 2 below. The maximum load is expressed as an index with the maximum load of the conventional pneumatic tire being 100, and the larger the value, the larger the maximum load, indicating that pinch cuts are less likely to occur.

  From the test results, the pneumatic tires of Examples 1 and 2 to which the present invention is applied provided with the radially outer reinforcing layer and the radially inner reinforcing layer are less likely to cause a pinch cut compared to the conventional pneumatic tire. I understand that.

[Test Example 3]
For pneumatic tires having flatness ratios of 50%, 55%, 60%, and 65%, four types of pneumatic tires having different rigidity differences between the radially outer reinforcing layer and the radially inner reinforcing layer with respect to the respective flatness ratios. Prepared and investigated the relationship between the pinch cut occurrence position and the rigidity difference. In the test, a pinch cut was generated and the load was increased until air escaped from the tire side portion, and then the position where the pinch cut occurred was examined. The numerical values in Table 1 below represent the number of pinch cuts. In addition, “outside” and “inside” in the table indicate the positions where pinch cuts occurred, and “outside” indicates that pinch cuts occurred in the carcass ply on the outer side in the tire radial direction of the folded portion, “Inner” indicates that a pinch cut has occurred in the carcass ply on the inner side in the tire radial direction of the folded portion.
The outer reinforcing layer and the inner reinforcing layer were both configured to include an organic fiber cord.
For pneumatic tires with a flatness ratio of 50% and 55%, the rigidity of the radially inner reinforcing layer is made higher than that of the radially outer reinforcing layer, and the pneumatic tire has a flatness ratio of 60% and 65%. Is set so that the rigidity of the radially outer reinforcing layer is higher than the rigidity of the radially inner reinforcing layer.

From the test results, in a pneumatic tire with a flatness ratio of 60% or more, it is likely to occur in the radially outer carcass cord of the folded portion, but the rigidity difference between the radially outer reinforcing layer and the radially inner reinforcing layer should be 30% or more. Thus, it can be seen that pinch cuts occurring in the radially outer carcass cord of the folded portion can be suppressed.
Moreover, in a pneumatic tire having a flatness ratio of 55% or less, it is likely to occur in the radially outer carcass cord of the folded portion, but by setting the difference in rigidity between the radially outer reinforcing layer and the radially inner reinforcing layer to be 30% or more, It can be seen that pinch cuts that occur in the carcass cord on the radially outer side of the folded portion can be suppressed.

[Test Example 4]
The inventors conducted the same test as in Test Example 1 and examined the position where the pinch cut of the carcass cord occurred. As shown in the test results of Table 4 below, the range from 0.62 to 0.66 L3 from the radially outer end of the radially outer reinforcing layer to the tire side portion side along the carcass ply and the center of the bead core 18 It can be seen that carcass cord reinforcement may be provided in a range of 0.62 to 0.66 L3 from the point where the vertical line VL1 passing through the carcass cord intersects the tire side portion along the carcass ply.
In the column of occurrence position of pinch cut in Table 4 below, “0” indicates the position of L3 from the maximum tire width position 20C of the carcass ply 20 to the tire equatorial plane CL side along the carcass ply 20. Further, “less than 0” means a position on the tire equatorial plane side with respect to the position of L3.

［その他の実施形態］
以上、本発明の一実施形態について説明したが、本発明は、上記に限定されるものでなく、上記以外にも、その主旨を逸脱しない範囲内において種々変形して実施可能であることは勿論である。
上記実施形態では、径方向外側補強層３４及び径方向内側補強層３６が有機繊維コードを含んで構成された例、径方向外側補強層３４及び径方向内側補強層３６がサイドゴムよりも硬いゴムから構成した例を説明したが、本発明はこれに限らず、径方向外側補強層３４及び径方向内側補強層３６は少なくともサイドゴムよりも剛性が高い部材であれば、上記実施形態で記載した材料以外、例えば、無機繊維コードを含んでいても良く、繊維等の補強材を含んだゴム等を用いても良く、有機繊維や無機繊維等で織られた織物や不織布、合成樹脂シート等を用いても良い。
上記実施形態では、径方向外側補強層３４及び径方向内側補強層３６をカーカスプライ２０に沿って配置したが、カーカスコード２１Ａの補強が十分であれば何れか一方だけを配置しても良い。 In the column of pinch cut occurrence position in Table 5 below, “0” indicates the position of L3 from the tire maximum width position 20C of the carcass ply 20 to the bead core side along the carcass ply 20. “Less than 0” means the bead core side (inner side in the tire radial direction) from the position of L3.

[Other Embodiments]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above, and other various modifications can be made without departing from the spirit of the present invention. It is.
In the above-described embodiment, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are configured to include organic fiber cords, and the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are made of rubber harder than the side rubber. Although the example which comprised was demonstrated, this invention is not restricted to this, As long as the radial direction outer side reinforcement layer 34 and the radial direction inner side reinforcement layer 36 are members whose rigidity is higher than a side rubber at least, it is other than the material described in the said embodiment. For example, inorganic fiber cords may be included, rubber including reinforcing materials such as fibers may be used, woven or non-woven fabrics woven with organic fibers or inorganic fibers, synthetic resin sheets, etc. Also good.
In the above embodiment, the radially outer reinforcing layer 34 and the radially inner reinforcing layer 36 are disposed along the carcass ply 20, but only one of them may be disposed as long as the carcass cord 21A is sufficiently reinforced.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Bead part 14 Tire side part 16 Tread part 18 Bead core 20 Carcass ply 20C The maximum width position of the tire of a carcass ply
21A Carcass cord VL1 First vertical line VL2 Second vertical line 26 Side rubber 34 Radial outer reinforcing layer (radial outer reinforcing material)
35A Organic fiber cord 36 Radial inner reinforcement layer (radial inner reinforcement)
38 rims 40 steps
40A Upper surface 42 Rim flange P Maximum tire width end L Horizontal distance L1 Length of radially outer reinforcing layer (length of radially outer reinforcing material)
L2 Length of radially inner reinforcing layer (length of radially inner reinforcing material)
L3 The length from the inner radial end of the radial inner reinforcing layer to the maximum tire width position of the carcass ply, and the length from the outer radial end of the radial outer reinforcing layer to the maximum tire width position of the carcass ply

Claims (11)

A carcass ply configured to include a plurality of carcass cords and formed in a toroidal shape across a pair of bead cores;
A tread portion disposed on the outer side in the tire radial direction of the carcass ply;
A tire side portion disposed between the tread portion and the bead core and disposed on the outer side in the tire width direction of the carcass ply;
In a pneumatic tire having a reinforcing material disposed along the carcass ply on the inner side in the tire width direction from the tire side portion,
In a state where the pneumatic tire is mounted on a standard rim and a prescribed internal pressure is tensioned, the pneumatic tire is pressed against a step portion formed higher than a road surface to be grounded and folded at the tire maximum width position, When the tire inner surface from the tire maximum width position to the bead core comes into contact with the opposite tire inner surface,
The reinforcing member has one end on a vertical line passing through the center of the bead core and the other end at a position of 0.58 to 0.62 L with respect to a horizontal distance L from the center of the bead core to the maximum tire width. Pneumatic tire to be installed. The reinforcing material includes a radially outer reinforcing material disposed in a tire radial direction outer portion of a portion where the bead portion, the tire side portion, and the tread portion are folded, the bead portion, the tire side portion, The pneumatic tire according to claim 1, further comprising: a radially inner reinforcing member disposed at a radially inner portion of the tire in a portion where the tread portion is folded. The pneumatic tire according to claim 2, wherein when the tire flatness is 55% or less, the rigidity of the radially inner reinforcing member is set higher than the rigidity of the radially outer reinforcing member. The pneumatic tire according to claim 2, wherein when the tire flatness is 60% or more, the rigidity of the radially outer reinforcing member is set higher than the rigidity of the radially inner reinforcing member. The pneumatic tire according to claim 2 or 3, wherein a rigidity difference between the rigidity of the radially outer reinforcing member and the rigidity of the radially inner reinforcing member is 30% or more. The pneumatic tire according to any one of claims 1 to 5, wherein the reinforcing material is provided in close contact with an outer surface or an inner surface of the carcass ply. The pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing material includes an organic fiber cord. The pneumatic tire according to any one of claims 1 to 6, wherein the reinforcing material is formed of a rubber harder than a side rubber forming a tire side portion. A method for installing a reinforcing material for a pneumatic tire including a plurality of carcass cords and including a carcass ply extending from one bead core to the other bead core,
A tread portion is mounted on a step portion provided higher than the road surface on which the pneumatic tire contacts the ground so that the bead core is positioned above the step portion. Between the first vertical line passing through the center of the bead core and the tire maximum width end in a state where the bead portion, the tire side portion, and the red portion are sandwiched and folded so as to protrude outward in the tire width direction. When the horizontal distance from the passing second vertical line is L, the horizontal length from the first vertical line to the second vertical line is set to 0.58 to 0.62 L. A method for installing a reinforcing material for a pneumatic tire, in which a reinforcing material for reinforcing a carcass cord is arranged. A pair of beads,
A tire side portion connected to the outside in the tire radial direction of the bead portion;
A tread portion straddling one tire side portion and the other tire side portion;
A carcass ply configured to include a plurality of carcass cords and straddling a bead core embedded in one of the bead portions to a bead core embedded in the other bead core;
A belt layer disposed on the outer side in the tire radial direction of the carcass ply;
A radially outer reinforcing material arranged along the carcass ply from the end of the belt layer toward the tire equatorial plane side and the tire side part side to reinforce the carcass cord;
The radially outer reinforcing material is separated from the radially outer reinforcing material, extends from the bead core side toward the tire side portion side, and the radial outer reinforcing material along the carcass ply when viewed in a section along the tire rotation axis. A radially inner reinforcing material for reinforcing the carcass cord having the same length as the length;
Pneumatic tire having The length of the radially outer reinforcing member is L1, the length of the radially inner reinforcing member is L2, and the length from the radially inner end of the radially inner reinforcing member to the tire maximum width position of the carcass ply is L3, L1 and L2 are 0.62 to 0.66L3, where L3 is a length from the radially outer end of the radially outer reinforcing material to the maximum tire width position of the carcass ply. The pneumatic tire according to 10.

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