JP2015042545A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new pneumatic tire capable of reducing weight without impairing steering stability.SOLUTION: A pneumatic tire includes a division recessed part 6 formed by a straight line or an arc of a radius 10 mm to 200 mm or combination of those, on an outer surface of a tire side portion, in a tire meridian cross section while the tire is assembled to an application rim and inner pressure is filled. The uppermost end of a flange 5b of the application rim 5 is made to be a reference, the outer side of the reference in a tire radius direction is made to be positive area, and the inner side of the reference in the tire radius direction is made to be negative area. Thereafter, the division recessed part 6 includes a division recessed part lower end 6a which becomes a tire radius direction innermost end within a range of -5 mm to +10 mm from the reference.

Description

  The present invention relates to a pneumatic tire that achieves both weight reduction and steering stability, and can be advantageously used as a heavy-duty pneumatic tire mounted on a heavy vehicle such as a truck or a bus. .

  In pneumatic tires, further weight reduction is demanded with the aim of reducing material and improving fuel efficiency, and it has been studied to provide a recess on the outer surface of the tire to reduce the thickness of the rubber. As a technique, for example, a pneumatic radial tire disclosed in Patent Document 1 is known.

JP 2000-301916 A

  By the way, for the purpose of significantly reducing the weight, if the concave portion provided on the side of the tire is expanded to the vicinity of the rim, the contact area between the bead portion and the rim flange will decrease, and the bead portion will collapse around the bead core. The steering stability may deteriorate. In particular, heavy load tires such as truck and bus tires tend to generate the above-mentioned tendency, and further reduction in weight and handling stability have been demanded.

  An object of the present invention is to provide a novel pneumatic tire that can be reduced in weight without impairing steering stability.

The present invention extends from a tread portion to a sidewall portion and a bead portion, which are tire side portions, in a toroidal shape, and around the bead core disposed in the bead portion, its end portion extends from the inside to the outside of the tire. In a pneumatic tire having at least one carcass ply having a wound winding part,
A section recess formed by a straight line, an arc having a radius of 10 mm to 200 mm, or a combination thereof is provided on the outer surface of the tire side portion in a tire meridian section in a state where it is assembled to an applicable rim and filled with an internal pressure. Is the innermost end in the tire radial direction within the range of −5 mm to +10 mm from the reference when the tire radial outer side is a positive region and the inner side is a negative region with respect to the flange uppermost end of the applicable rim. It has the division recess lower end which becomes.

  Here, “the state of being assembled to the applied rim and filled with the internal pressure” means that the tire is assembled to the applied rim defined by a predetermined industrial standard, and the maximum load of a single wheel at the applied size defined by the industrial standard ( The air pressure corresponding to the maximum load capacity) is filled, and it means no load. With regard to such industrial standards, standards that are effective in the regions where tires are produced or used are defined, and these standards include, for example, “The Tire and Rim Association Inc. YEAR BOOK” (including design guides) in the United States. ) In Europe by “The European Tire and Rim Technical Organizations Manual” and in Japan by “JATMA Year Book” of the Japan Tire Automobile Tire Association.

  In the tire configured as described above, the bead portion includes a bead edge portion that rises from an outermost end portion that is an outermost end in a tire width direction of a bottom surface of the bead portion and that is connected to a lower end of the partition recess, In the tire meridian cross section in a state where the pressure is assembled and filled with internal pressure, it is desirable that a region of 60% to 100% of the bead edge is in contact with the flange of the application rim.

  In the tire configured as described above, it is desirable that the bead edge has a concave shape.

  In the tire configured as described above, the bead bottom surface angle, which is the angle of the bottom surface of the bead portion, is desirably in the range of 0 ° to + 10 ° with respect to the bead seat angle, which is the bead seat angle of the rim.

  The partition recess provided on the outer surface of the tire side portion is -5 mm from the reference when the outer side in the tire radial direction is set as the positive region and the inner side is set as the negative region. Because it has a lower end of the compartment recess that is the innermost end in the tire radial direction in the range of ~ 10mm, it is possible to expand the compartment recess to a position where it does not cause the bead to collapse, further reducing the weight Is possible.

  Since 60% to 100% of the edge of the bead is in contact with the flange of the applied rim when it is assembled to the applied rim and filled with internal pressure, the area around the inner edge of the compartment recess is excessive even when a load is applied to the tire Therefore, the occurrence of cracks is suppressed, the bead can be stably supported, and steering stability can be ensured.

  Since the bead edge has a concave shape, the bead edge and the rim flange easily come into uniform contact with each other when a load is applied to the tire, and the bead part is stably supported to improve driving stability. It can be secured.

  Since the bead bottom surface angle, which is the angle of the bottom surface of the bead portion, is in the range of 0 ° to + 10 ° with respect to the bead seat angle, which is the bead seat angle of the rim, the bead portion collapses inward in the tire width direction. It is possible to prevent this and to ensure the handling stability.

It is the figure which showed the tire meridian cross section in the state which assembled | attached to the application rim and was filled with the internal pressure about embodiment of the pneumatic tire according to this invention about the right half part of a tire. It is the figure which showed the tire meridian cross section before the assembly | attachment to an application rim about the right half part of a tire about embodiment of the pneumatic tire according to this invention. It is a figure showing a bead bottom surface angle and a bead seat angle. When it is assumed that a tire is filled with a predetermined air pressure and assembled to an applicable rim and no load is applied, the bead bottom surface angle relative to the bead seat angle is (a ) Is a diagram showing a positive case and (b) is a diagram showing a negative case. It is a principal part expanded sectional view of the pneumatic tire which showed the reference tire (conventional example).

  Hereinafter, the present invention will be described more specifically with reference to the drawings.

  FIG. 1 is a view showing a tire meridian cross section in a state in which the pneumatic tire according to an embodiment of the present invention is assembled to an applicable rim and filled with an internal pressure, with respect to the right half of the tire, and a bead portion on the left side (not shown) Is the same configuration.

  Reference numeral 1 in the figure denotes a bead portion on the right side of the tire that is connected in the circumferential direction of the tire. The bead portion 1 is connected to a sidewall portion 2 that extends substantially outward in the radial direction of the tire to form a tire side portion, not shown. It is connected to the tread and has a toroidal shape.

  The bead portion 1 has a bottom surface 1a that is seated on an application rim 5 that will be described later, and an outermost end portion 1b that is the outermost end in the tire width direction of the bottom surface 1a.

  Reference numeral 3 denotes a bead core disposed in the bead portion 1 and extends in the circumferential direction of the tire to form a ring shape. The bead core 3 is formed by bundling a plurality of bead wires, and the cross-sectional shape of the bead core 3 can be selected from various shapes such as a square and a circle in addition to the hexagon illustrated.

  Reference numeral 4 denotes at least one carcass ply. The carcass ply 4 has a winding portion 4b around the bead core 3 in which an end portion 4a is wound from the inside toward the outside. The end portion 4a is not limited to a turn-up structure extending from the winding portion 4b to the outer side in the tire radial direction as shown in the figure, and may be configured to be wound around the bead core 3 approximately once.

  The carcass ply 4 has a reinforcing ply cord embedded in a carcass rubber. The ply cord may extend at any angle with respect to the circumferential direction of the tire, but in general, in order to satisfy various performances required for the tire, a radial direction substantially orthogonal to the circumferential direction of the tire Is preferable. Here, “substantially orthogonal” specifically means that the angle with respect to the circumferential direction of the tire is in the range of 85 ° to 95 °, and takes into account manufacturing errors. This cord can be selected in various ways, and is adopted from, for example, organic fibers such as aramid, polyethylene, and nylon, glass fibers, and steel.

  Reference numeral 5 denotes an applicable rim, which includes a bead seat 5a on which the bottom surface 1a of the bead portion 1 is seated, and a flange 5b that rises from the outer end of the bead seat 5a and curves in a direction that protrudes outward in the tire radial direction. Yes.

Reference numeral 6 denotes a partition recess, in which the tire side portion is thinned. The partition recess 6 is formed by using one or a plurality of straight lines, circular arcs having a radius R ₁ (R ₁ = 10 mm to 200 mm), or a combination thereof, and is connected to the tire side portion in the circumferential direction. It has a concave shape. If the radius R ₁ is within the above range, even if it is an arc with a small radius, stress concentration does not easily occur when the tire is bent, and durability is not impaired. The amount of twisting can be increased, and the weight can be reduced.

  The partition recess lower end 6a, which is the innermost end in the tire radial direction of the partition recess 6, is a tire meridian section in a state where the partition recess 6 is assembled to the applicable rim 5 and filled with the internal pressure, and is based on the uppermost end of the flange 5b. Further, when the outer side in the tire radial direction is set as the positive region and the inner side is set as the negative region, the distance A from the reference is preferably in the range of A = −5 mm to +10 mm. When the distance A is within the above range, even when the partition recess lower end 6a is positioned on the inner side in the tire radial direction, the partition recess 6 is not positioned almost directly beside the bead core 3, and a load is applied. In addition, it is possible to prevent the bead portion 1 from collapsing and to ensure steering stability. In addition, even when the partition recess lower end 6a is located on the outer side in the tire radial direction, when a load is applied, there is no portion that does not come into contact with the flange 5b and has almost no effect of supporting the bead portion 1. Therefore, it is possible to sufficiently widen the meat removal range and to reduce the weight.

  The distance t from the carcass ply 4 to the tire side, which is the thickness of the rubber on the outside of the tire side, is the distance from the normal line standing from the carcass ply 4 to the outer surface of the tire side. And gradually increases from the maximum width position W of the tire to the partition recess lower end 6a. For this reason, a bead side part has the cyclic | annular protrusion shape from which the thickness of rubber | gum becomes the thickest in the circumferential direction of a tire in the said division recess lower end 6a.

  Reference numeral 7 denotes a bead edge, which rises from the outermost end 1b and is connected to the partition recess lower end 6a. The bead edge 7 is preferably in a region of 60% to 100% of the bead edge 7 in contact with the flange 5b of the application rim 5 in a cross section of the tire meridian when assembled to the application rim 5. If it is the said range, even when the contact range of the said bead edge 7 and the said flange 5b is narrow, when a load is applied, the whole surface of this bead edge 7 will contact this flange 5b, and the said bead part 1 can be supported. Even when the contact range of the bead edge 7 and the flange 5b is close to 100%, the vicinity of the partition recess lower end 6a is not crushed when a load is applied, and the occurrence of cracks can be suppressed.

  It is preferable that the bead edge portion 7 has a concave shape before being assembled to the application rim 5. As a result, the bead edge 7 and the flange 5b can easily be in uniform contact with each other in a state where a load is applied to the tire, and the bead 1 can be stably supported.

Further, as shown in FIG. 2, the bead edge portion 7 has a concave shape having a radius R ₂ before assembly to the application rim 5, and the radius R ₂ is larger than the radius R _{f of the} flange 5b. It is more preferable. Thereby, in the assembly state to the application rim 5, the partition recess lower end 6a is not pressed against the flange 5b due to the internal pressure of the tire to be deformed, and generation of wrinkles, cracks and the like can be suppressed.

In the tire configured as described above, a reference line L passing through the outermost end portion 1b and parallel to the tire rotation axis is set, and an angle of the bottom surface 1a with respect to the reference line L is a bead bottom surface angle θ ₁ , and the reference line L is when the angle of the bead seat 5a and bead seat angle theta _2, the bead bottom face angle theta ₁ is preferably to the bead seat angle theta ₂ in the range of 0 ° ~ + 10 °. Here, when it is assumed that the bead bottom surface angle θ ₁ is 0 ° with respect to the bead seat angle θ ₂ , the tire is filled with a predetermined air pressure and assembled to the application rim 5 so that no load is applied. The bead bottom surface angle θ ₁ is in a positive range with respect to the bead sheet angle θ _{2. As} shown in FIG. 3A, the bottom surface 1a is located on the inner side of the bead sheet 5a. The bead bottom surface angle θ ₁ is in a negative range with respect to the bead sheet angle θ ₂ , as shown in FIG. 3B, between the bottom surface 1a and the bead sheet 5a. A state where a gap is generated. In the positive range, the portion where the bottom surface 1a enters the inside of the bead sheet 5a is a portion which becomes a crushing margin in a state where the bottom surface 1a is actually assembled to the application rim 5 and filled with internal pressure, and the bead portion 1 It works to fall down on the outside in the tire radial direction. If it is within the angle range, the bead portion 1 is not easily tilted inward in the tire width direction due to a gap between the bottom surface 1a and the bead sheet 5a, and the crushing margin becomes too large. Since the adhesion between the portion 1 and the applied rim 5 is not impaired, the bead portion 1 can be stably supported.

  The tire size is 275 / 80R22.5, the dimensional relationship in Table 1, and the conforming tires 1 to 3 and comparative tires 1 to 3 having the structure shown in FIG. 1 and the reference tire having the structure shown in FIG. ), And the tire mass and maneuverability evaluation were confirmed for each tire.

  As for the mass of the tire, a conventionally used tire is used as a reference tire, and the mass of each tire is shown as an index in Table 1 with the mass of the reference tire being 100. The smaller the number, the lighter.

For the evaluation of maneuverability, each tire was assembled on a rim having a size of 22.5 × 7.50 (flange radius R _f = 12.7 mm, flange taper angle = 15 °), and the load was measured using an indoor drum tester. in 3400kg, confirmation was carried out by maneuverability evaluation value C _P. 100 the reference tire and maneuverability evaluation value C _P of each of the tires as indexed in Table 1. Larger numbers indicate better performance.

  As a result, a tire (reference tire) having a large distance from the uppermost end of the flange to the lower end of the compartment recess cannot be reduced in weight. Further, the distance from the uppermost flange end to the lower end of the compartment recess is small, and the bead edge has a concave shape (comparative tire 1) and the contact range of the bead edge and the angle of the bead bottom with respect to the bead sheet is large. The tire (comparative tire 2) is subject to steering stability.

  The tires (applicable tires 1 to 3) in which the distance from the uppermost end of the flange to the lower end of the compartment recess and the contact range of the bead edge are within a predetermined range and the bead edge is a concave inner end (applicable tires 1 to 3) are reduced in weight. As well as handling stability. Moreover, it was confirmed that the tires (compatible tires 2 and 3) in which the angle of the bottom surface of the bead portion with respect to the bead sheet is in a predetermined range are further excellent in steering stability and more suitable.

  According to the present invention, it is possible to stably supply a novel pneumatic tire that does not impair steering stability even if a recess provided on the side of the tire for weight reduction is expanded to the vicinity of the rim.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Bead core 4 Carcass ply 5 Applicable rim 5a Bead sheet 5b Flange 6 Compartment recess 6a Compartment recess lower end 7 Bead edge part

In the tire configured as described above, the bead portion includes a bead edge portion positioned on the inner side in the tire radial direction at the lower end of the partition recess, and the bead edge portion has a concave shape with a radius of 15 to 20 mm. The application rim is a 15 ° deep rim having a flange radius of 12.7 mm .

Claims (4)

A winding that extends in a toroidal shape from the tread portion to the sidewall portion and bead portion, which are the tire side portions, and the end portion of the bead core is wound from the inside to the outside of the tire around the bead core. In a pneumatic tire having a turning portion and including at least one carcass ply,
A section recess formed by a straight line, an arc having a radius of 10 mm to 200 mm, or a combination thereof is provided on the outer surface of the tire side portion in a tire meridian section in a state where it is assembled to an applicable rim and filled with an internal pressure. Is the innermost end in the tire radial direction within the range of −5 mm to +10 mm from the reference when the tire radial outer side is a positive region and the inner side is a negative region with respect to the flange uppermost end of the applicable rim. A pneumatic tire characterized by having a lower end of a compartmental recess.   The bead portion includes a bead edge portion that rises from the outermost end, which is the outermost end in the tire width direction of the bottom surface of the bead portion, and is connected to the lower end of the partition recess, and is assembled to the applicable rim and filled with internal pressure. The pneumatic tire according to claim 1, wherein an area of 60% to 100% of the edge of the bead is in contact with a flange of the application rim in a tire meridian section.   The pneumatic tire according to claim 2, wherein the bead edge has a concave shape.   The bead portion has a bead bottom surface angle that is an angle of a bottom surface of the bead portion in a range of 0 ° to + 10 ° with respect to a bead seat angle that is an angle of a bead seat of the rim. The pneumatic tire according to Crab.

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