JP5878384B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that is intended to save resources by reducing the amount of rubber used while ensuring ride comfort and side cut resistance.

  Conventionally, as a pneumatic tire used for a passenger car or the like, a tire that has a toroidal shape between bead cores embedded in a pair of bead portions and has a carcass formed by folding each bead core from the inside to the outside is known. (See Patent Document 1).

  Further, in recent years, efforts have been made to save resources in tires due to environmental efforts, and attempts have been made to reduce the amount of rubber used by reducing the thickness of the sidewall portion of the tire. However, as in the tire 100 shown in FIG. 4, when the folded portion 113b of the carcass 113 made of one carcass ply terminates near the center of the sidewall portion 107, it is in the region from the folded end 113c of the carcass to the belt end 115c. Only one carcass ply is placed. If the thickness of the side wall portion 107 is reduced, sufficient rigidity cannot be secured, and the durability against scuffing and trauma (side cut) with running curb stones is reduced. There was a problem of inviting. In order to solve such a problem, a so-called envelope structure tire is known in which the folded portion of the carcass is extended to a position where it overlaps with the belt to supplement the strength of the sidewall portion.

JP-A-8-48118

  However, when the envelope structure described above is applied to a pneumatic tire, the rigidity of the entire sidewall portion can be increased and the durability against side cuts can be increased, but on the other hand, since the vertical spring of the tire also increases, the impact from the road surface is reduced. There is a problem in that the ability to absorb at the sidewall portion is reduced and the ride comfort is deteriorated.

  Therefore, an object of the present invention is to provide a pneumatic tire capable of reducing the amount of rubber used without lowering the side cut resistance and deteriorating riding comfort.

The present invention has been made to solve the above problems, and a pneumatic tire according to the present invention is a tire that is folded around a bead core from a main body portion that extends in a toroidal shape between a pair of bead cores. A carcass made of one carcass ply having a folded portion extending radially outward and rubber-coated with a ply cord; a belt made of at least one belt layer disposed on the outer side of the carcass in the tire radial direction; A pneumatic tire including a bead filler extending from the bead core to the outer side in the tire radial direction between the main body portion and the folded portion, wherein the folded portion extends between the main body portion of the carcass and the belt. In the sidewall portion, a region of 10% of the tire cross-section height is sidewalld from the tire maximum width position to the inside and outside in the tire radial direction. When the wheel portion central region is used, the thickness from the outer surface to the carcass ply in the sidewall portion central region is 3 mm or less, and the tire radial height of the bead filler is 15% or less of the tire cross-sectional height. der is, the tread portion has a transverse groove which forms a lateral block extending across the tread end, the lateral grooves, than 15% of the area of the tire section height from the outermost end in the tire radial direction An imaginary straight line that contacts the groove bottom line of the lateral groove is a straight line parallel to the tire equator plane within the cross section in the width direction of the tire that is terminated inward in the tire radial direction and assembled to a predetermined rim and filled with a predetermined internal pressure. Θ1 ≧ θ2 where θ1 is the angle at which the imaginary straight line in contact with the tire outline at the same position in the tire width direction and the position where the angle θ1 is measured intersects with the straight line parallel to the tire equatorial plane. Satisfaction It is characterized in that to. Here, the “tire maximum width position” refers to a cross section in the tire width direction in a no-load state (hereinafter referred to as “predetermined state”) in which a pneumatic tire is assembled to a regular rim, filled with a regular internal pressure, and no load is applied. The “width of the tire cross section” means a value that is ½ of the difference between the tire outer diameter and the rim diameter in the predetermined state. The “regular rim” means “standard rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. “Regular internal pressure” means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. . The “thickness from the outer surface to the carcass ply in the sidewall central region” means the shortest distance from the outer surface of the sidewall portion to the outer surface in the tire width direction of the folded portion of the carcass in the sidewall central region. Say.

In such a pneumatic tire, the amount of rubber to be used can be reduced by setting the thickness from the outer surface to the carcass ply in the central region of the sidewall portion to 3 mm or less. By extending between the main body and the belt, it is possible to compensate for a lack of rigidity of the sidewall due to the reduced thickness, and to suppress a reduction in side cut resistance. Further, by setting the height of the bead filler in the tire radial direction to 15% or less of the tire cross-sectional height, it is possible to prevent the vertical spring of the tire from becoming too high and to prevent the ride comfort from deteriorating. According to this, the thickness of the side wall portion does not become too thin due to the groove, and the occurrence of side cuts can be further reduced. The “predetermined rim” here is the normal rim described above, and the “predetermined internal pressure” represents the normal internal pressure. The “tread end” refers to an outermost contact portion in the tire width direction when a pneumatic tire is assembled to the regular rim, filled with a regular internal pressure, and a regular load is applied. “Regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS AT for TRA” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” for ETRTO.

  Furthermore, while lowering the height of the bead filler in the radial direction of the tire and extending the carcass folding part between the carcass main body and the belt, when the tire touches down, the deformation around the rim flange is increased, It is possible to reduce the collapse deformation of the shoulder portion with respect to the ground contact surface. This makes it difficult for the sidewall portion to come into contact with the projections on the road surface during traveling, so that the occurrence of side cuts can be reduced.

  In the pneumatic tire of the present invention, the width of the belt layer disposed on the innermost side in the tire radial direction is preferably 75% or more of the maximum width of the tire. It is possible to increase the rigidity of the portion, suppress the collapse deformation of the shoulder portion with respect to the ground road surface, and further reduce the occurrence of side cuts.

  In the pneumatic tire of the present invention, the distance in the tire width direction between the tip of the folded portion of the carcass and the tip of the belt is preferably 10 to 30 mm. In addition, it is possible to prevent the side cut resistance of the tire from being lowered and to suppress the deterioration of ride comfort.

  In the pneumatic tire according to the present invention, the number of ply cords driven in the carcass ply is preferably 50 to 70/5 cm. According to this, the rigidity of the carcass ply is increased to increase the side It is possible to increase the rigidity of the wall portion and more reliably suppress a decrease in side cut resistance.

  Further, in the pneumatic tire of the present invention, it is preferable that the thickness of the ply cord is 1700 dtex / 2 or less, and according to this, the rigidity of the ply cord does not become too large, so that the longitudinal spring of the tire is excessive. The deterioration of ride comfort can be suppressed.

  Further, the thickness from the outer surface in the sidewall region central region to the carcass ply is 1 mm or more, and is smaller than the thickness from the inner surface in the sidewall region central region to the outer surface of the carcass ply. Preferably, according to this, the side cut resistance and the rigidity of the sidewall portion can be ensured. Here, the “thickness from the inner surface in the sidewall region central region to the outer surface of the carcass ply” means the surface on the outer side in the tire width direction of the folded portion of the carcass from the inner surface of the sidewall portion in the sidewall region central region. The shortest distance to.

  Furthermore, it is preferable that the height of the bead filler in the tire radial direction is 5 mm or more, and according to this, it is possible to secure the rigidity of the bead portion and suppress deterioration in ride comfort and rolling resistance.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can aim at reduction of the amount of rubber | gum used can be provided, without being accompanied by the fall of side-cut-proof property and deterioration of riding comfort.

1 is a sectional view (half view) in the width direction of a tire according to an embodiment of the present invention. (A) is the width direction sectional drawing at the time of the load load of the tire of one Embodiment of this invention, (b) is width direction sectional drawing at the time of the load load of the conventional tire. (A) is a fragmentary sectional view for demonstrating the lateral groove of the tire as an example of embodiment of this invention, (b) and (c) are the partial cross sections for demonstrating the tire as another example. FIG. It is sectional drawing of the width direction of the pneumatic tire of conventional structure.

  Hereinafter, a pneumatic tire according to an embodiment of the present invention (hereinafter also simply referred to as a tire) will be described in detail with reference to the drawings. In the figure, symbol R indicates a rim that can be the above-mentioned regular rim, and symbol RF indicates a flange portion of the rim. FIG. 1 shows the above-described predetermined state in which the pneumatic tire 1 is assembled to the regular rim R, the regular internal pressure is filled, and no load is applied.

  As shown in FIG. 1, the tire 1 of the present embodiment includes a tread portion 3 that forms a tread surface of the tire, a pair of sidewall portions 7 that are connected to the outer side in the width direction of the tread portion 3 via a shoulder portion 5, and these A pair of bead portions 9 are provided on the inner side in the radial direction of the side wall portions 7, and bead cores 11 are respectively embedded. A carcass 13 composed of a single carcass ply has a main body 13a extending in a toroidal shape between the bead cores 11 inside the tire 1, and a continuous extension from the main body 13a to wrap around the bead core 11 from the inside to the outside. The bead portion 9, the sidewall portion 7, the shoulder portion 5, and the tread portion 3 are reinforced. Further, on the outer side in the tire radial direction of the carcass 13, a belt 15 composed of at least one belt layer 15a is disposed so as to cover the folded end 13c of the carcass. Further, a bead filler 17 extending in a tapered manner is provided on the outer side of the bead core 11 in the tire radial direction, and the height h in the tire radial direction is 15% or less of the tire cross-section height SH. Further, a thickness t from the outer surface to the carcass ply in the sidewall central region 21 which is a range of 10% of the tire cross-sectional height from the tire maximum width position M to the inside and outside in the tire radial direction is 3 mm or less.

  The carcass ply that forms the carcass 13 of the tire 1 is a ply cord covered with ply rubber. The ply cord is polyester of 1100 dtex / 2, twist number 47 × 47 times / 10 cm, and the number of drivings is 50 to 70. This can be 5cm, but is not limited to this.

  The tire 1 having the above-described configuration reduces the amount of rubber used by reducing the thickness of the sidewall portion central region 21, and further reduces the rigidity due to the reduced thickness of the sidewall portion central region 21. Since this is compensated by the overlap of the carcass main body 13a and the folded-back portion 13b arranged in the portion, it is possible to prevent a reduction in side cut resistance.

  In addition to reducing the thickness of the sidewall central region 21, the tire radial direction height h of the bead filler 17 is set to 15% or less of the tire cross-section height SH, so that the tire 1 can be made by the bead filler having high rigidity. It is possible to prevent the vertical springs from excessively increasing and to prevent the ride comfort from deteriorating.

  FIG. 2A shows how the tire 1 having the above configuration is deformed when a load is applied. Similarly, FIG. 2B shows a state of the tire 100 having a conventional structure when the load is applied. When these two are compared, the tire 1 has a smaller radial height of the bead filler 17 than the tire 100. As a result, the rigidity around the rim flange RF is small, and the rigidity around the shoulder portion 5 is increased by extending the carcass folded portion 13b to a position overlapping the belt 15, so that the collapse of the rim flange RF is large, and the shoulder portion 5 The collapse deformation with respect to the nearby ground contact surface T is small. That is, the angle α of the tire outer surface with respect to the road surface T of the tire 1 shown in FIG. 2A is larger than the angle α ′ of the tire outer surface with respect to the road surface T of the tire 100 shown in FIG. It is difficult for the protrusions on the road surface to come into contact with the sidewall portion 7 and the occurrence of failure due to the side cut can be suppressed.

  In the tire 1 of the present invention, the width w (shown in FIG. 1) of the belt layer 15a disposed on the innermost side in the tire radial direction is 75% or more of the maximum width SW of the tire 1. Preferably, according to this, the rigidity of the shoulder part 5 can be improved, the collapse deformation of the shoulder part 5 with respect to the grounding road surface T can be suppressed, and the occurrence of side cuts can be more reliably reduced. More preferably, the width w of the belt layer 15a disposed on the innermost side in the tire radial direction is preferably 90% or less of the maximum width SW of the tire 1, and if it exceeds 90%, There is a possibility that the strain increases and the durability decreases.

  In the tire of the present invention, the distance in the tire width direction with the tip 15c (belt end) of the belt 15 that overlaps the folded end 13c of the carcass is preferably 10 to 30 mm. According to this, It can more reliably prevent deterioration of tire side-cut resistance and suppress deterioration in ride comfort. If the distance is less than 10 mm, the stress concentration is reduced by reducing the distance between the carcass folded end and the belt end. If the thickness exceeds 30 mm, the material may be extended to a portion where the stress concentration relaxation effect does not sufficiently work, which may lead to an unnecessary increase in weight.

  FIG. 3A is a cross-sectional view in the width direction in which the tire 1 shown in FIG. 1 is partially enlarged. A broken line indicated by reference numeral 31 indicates a groove bottom of a lateral groove forming the side block 33 in the tread portion 3. Represent. A point P at which the broken line 31 intersects with the contour line representing the outer shape of the tire is located within a region of 15% of the tire cross-section height SH from the outermost end in the tire radial direction, that is, from the outermost end in the tire radial direction. It is preferable that the lateral groove terminates in a region of 15% of the tire cross-section height SH. Since the thickness of the sidewall portion is thinner in the region inside the tire radial direction than the region of 15% of the tire cross-section height SH from the outermost end in the tire radial direction, a side cut is likely to occur. Since the thickness may be further reduced and the side cut may be more likely to occur, the occurrence of the side cut can be more reliably reduced by not arranging the lateral groove in this region.

  3 (b) and 3 (c) show a tire as another example of the present invention, in which the lateral groove has a tire diameter larger than the region of 15% of the tire cross-section height SH from the outermost end in the tire radial direction. It ends in the inner direction. Θ1 shown in FIG. 3 (b) represents an angle at which a virtual straight line contacting the groove bottom line 31 ′ of the lateral groove intersects with a straight line parallel to the tire equator plane, and θ2 shown in FIG. 3 (c) touches the tire outline. This represents the angle at which the virtual straight line intersects the straight line parallel to the tire equator plane. At this time, it is preferable that θ1 and θ2 have a shape that satisfies θ1 ≧ θ2, and according to this, the thickness of the sidewall portion is not excessively reduced by the groove, and the occurrence of sidecuts can be reduced. .

  In the pneumatic tire of the present invention, the number of ply cords driven into the carcass ply is preferably 50 to 70/5 cm. According to this, the side wall can be increased by increasing the rigidity of the carcass ply. It is possible to increase the rigidity of the portion and more reliably suppress a decrease in side cut resistance. For the same reason, it is more preferable that the number is 50 to 55/5 cm.

  Further, in the pneumatic tire of the present invention, it is preferable that the thickness of the ply cord is 1700 dtex / 2 or less, and according to this, the rigidity of the ply cord does not become too large, so that the longitudinal spring of the tire is excessive. The deterioration of ride comfort can be suppressed. For the same reason, it is more preferable that it is 1000 to 1400 dtex / 2.

  Further, the thickness t from the outer surface to the carcass ply in the sidewall portion central region 21 is 1 mm or more, and is smaller than the thickness t ′ from the inner surface to the outer surface of the carcass ply in the sidewall portion central region. More preferably, according to this, while ensuring the side cut resistance, the thickness inside the carcass can be secured to prevent the rigidity of the sidewall portion from excessively decreasing. Further, when the thickness t is less than 1 mm, the rigidity of the sidewall portion outside the carcass is excessively lowered and the side cut resistance is deteriorated, and when the thickness t ′ is smaller than the thickness t, There is a risk that the rigidity of the entire wall portion cannot be ensured and the ride comfort and rolling resistance are deteriorated.

  Further, in the tire of the present invention, the height h of the bead filler 17 in the tire radial direction is preferably 5 mm or more. According to this, the rigidity of the bead portion is ensured, so that the ride comfort and rolling can be ensured. The deterioration of the resistance can be suppressed, and if it is less than 5 mm, the rubber volume around the bead part becomes extremely small, so that it is easy to cause a manufacturing defect, and the rigidity of the bead part is insufficient and it is easy to come off from the rim. Or ride comfort may deteriorate.

  Next, tires according to the present invention were prototyped and performance evaluations were performed, which will be described below. All of the tires of the conventional example, the comparative example, and the examples 1 to 3 have a tire size of 175 / 65R14. Table 1 shows the configuration of each tire.

  Here, the “thickness t and thickness t ′” in Table 1 are the thickness t from the outer surface to the carcass ply in the central portion of the sidewall portion and the thickness from the inner surface to the outer surface of the carcass ply in the central portion of the sidewall portion. “bead filler height [%]” represents a ratio [%] of the height of the bead filler to the tire cross-section height SH in a cross-sectional view in the tire width direction. “Belt width [%]” represents the ratio [%] of the width of the innermost belt layer in the tire radial direction to the tire maximum width SW.

  Each of the above test tires was assembled on a 5.5J × 14 rim, with an internal pressure of 210kPa and a load of 3.7kN, with a square prism shape of 50mm in length and the tip pointed at an angle of 60 ° A metal piece (material: SUS) was pressed against the sidewall portion to penetrate, and the force required for the penetration was measured. The results are shown in Table 1. The results are expressed as an index with the conventional tire as 100, and the larger the value, the better the side cut resistance. In addition, the longitudinal spring (riding comfort) and the mass of the tire are represented by an index with the conventional tire as 100. It shows that riding comfort is excellent, so that the value of a vertical spring is small.

  From the test results in Table 1, it can be seen that the tires of the examples are excellent in side cut resistance and ride comfort, and the mass of the tire is reduced compared to the conventional tires by reducing the amount of rubber used. .

  Thus, according to the present invention, it is possible to provide a pneumatic tire capable of reducing the amount of rubber used without causing a decrease in side cut resistance and a deterioration in ride comfort.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 3 Tread part 5 Shoulder part 7 Side wall part 9 Bead part 11 Bead core 13 Carcass 15 Belt 17 Bead filler 21 Side wall part center area | region R rim RF rim flange

Claims (8)

A carcass formed of a single carcass ply having a main body portion extending in a toroidal shape between a pair of bead cores, and a folded portion extending from the main body portion around the bead core and extending outward in the tire radial direction and having a ply cord covered with rubber. When,
A belt composed of at least one belt layer disposed on the outer side in the tire radial direction of the carcass;
A pneumatic tire comprising a bead filler extending from the bead core to the outer side in the tire radial direction between the main body portion and the folded portion,
The folded portion extends between the body portion of the carcass and the belt;
Among the sidewall portions, when the region of 10% of the tire cross-section height is defined as the sidewall region central region from the tire maximum width position to the inside and the outside in the tire radial direction, the outer surface in the sidewall region central region The thickness to the carcass ply is 3mm or less,
Tire radial height of the bead filler state, and are less than 15% of the height tire section of,
The tread portion has a lateral groove that forms a side block extending across the tread edge, and the lateral groove is on the inner side in the tire radial direction from the outermost end in the tire radial direction to a region that is 15% of the tire cross-section height. In the cross section in the width direction of the unloaded tire that is assembled to a predetermined rim and filled with a predetermined internal pressure, an angle at which an imaginary straight line that contacts the groove bottom line of the lateral groove intersects with a straight line parallel to the tire equatorial plane θ1, θ1 ≧ θ2 is satisfied, where θ2 is an angle at which a virtual straight line in contact with the tire outline at the same position in the tire width direction as the position where the angle θ1 is measured intersects with a straight line parallel to the tire equatorial plane And pneumatic tires.   The pneumatic tire according to claim 1, wherein a width of the belt layer disposed on the innermost side in the tire radial direction is 75% or more of a maximum width of the tire. The pneumatic tire according to claim 1 or 2 , wherein a distance in a tire width direction between a tip of the folded portion of the carcass and a tip of the belt is 10 to 30 mm. The pneumatic tire according to any one of claims 1 to 3 , wherein a number of driving of the ply cord in the carcass ply is 50 to 70 / 5cm. The pneumatic tire according to any one of claims 1 to 4 , wherein a thickness of the ply cord is 1700 dtex / 2 or less. 2. The thickness from the outer surface in the sidewall region central region to the carcass ply is 1 mm or more, and is smaller than the thickness from the inner surface in the sidewall region central region to the outer surface of the carcass ply. The pneumatic tire according to any one of to 5 . The pneumatic tire according to any one of claims 1 to 6 , wherein a height of the bead filler in a tire radial direction is 5 mm or more. The pneumatic tire according to any one of claims 1 to 7, wherein the carcass is disposed such that an extension direction of the ply cord is inclined at an angle of approximately 90 ° with respect to a tire circumferential direction.

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