JP2012006483A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve noise performance, by arranging a protrusion on an outer surface of a buttress part and limiting the shape of the protrusion.SOLUTION: The protrusion 11 continuously extending in the tire circumferential direction by projecting outside in the tire radial direction, is formed on the outer surface 10n of the buttress part 10. The protrusion 11 is formed so that an angle θ formed by the center line G1 of a thickness of the protrusion 11 and a line in the tire radial direction is ≤30 degrees, and a distance T in the tire radial direction between the outer end 11x in the tire radial direction of the projection 11 and a plane h grounded by applying a normal load is 0.5-10 mm.

Description

  The present invention relates to a pneumatic tire having improved noise performance by providing a protrusion on the outer surface of a buttress and limiting its shape.

  Conventionally, in order to reduce noise during tire running, for example, a method of randomizing the shape of the tread block and its arrangement to disperse the noise frequency, a method of reducing the resonance volume by reducing the volume of the groove, Has proposed a method of improving the internal structure of the tire and the contour shape of the tire to make the tire less likely to vibrate.

  However, in these proposals, there is a case where the basic performance of the tire such as ride comfort and handling stability is deteriorated, or the noise reduction effect is not sufficient, and further noise countermeasures are required. Related technologies include the following.

Japanese Patent Laid-Open No. 2002-12006

  The present invention has been devised in view of the above-described problems. On the basis of providing a projection on the outer surface of the buttress portion and limiting its cross-sectional shape, noise generated in the tread portion is outward. The main object is to provide a pneumatic tire that improves noise performance by preventing leakage.

  The invention according to claim 1 of the present invention is a pneumatic tire having a tread portion and a buttress portion extending inward in the tire radial direction from both ends thereof, on the outer surface of the buttress portion on the outer side in the tire radial direction. Protrusion that protrudes and extends continuously in the tire circumferential direction, is mounted on a regular rim, is filled with regular internal pressure, is loaded with regular load, and the tire rotates in a regular load state with a camber angle of 0 ° and grounded on a flat surface In the tire meridian cross section including the axis, the protrusion has an angle θ formed by a center line of the thickness of the protrusion and a tire radial direction line of 30 degrees or less, and the tire radial outer end of the protrusion and the tire A tire radial distance T with respect to a plane is 0.5 to 10 mm.

  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the angle θ is 20 degrees or less.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the tire radial distance T is 1 to 5 mm.

  According to a fourth aspect of the present invention, in the projection, the intersection of the center line and a virtual buttress surface obtained by smoothly connecting outer surfaces other than the projection of the buttress portion is 10 in the tire cross-section height from the plane. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is formed at a position of -30%.

  The invention according to claim 5 is the pneumatic tire according to any one of claims 1 to 4, wherein the protrusion portion is tapered outward in the tire radial direction.

  In the pneumatic tire of the present invention, a protrusion is formed on the outer surface of the buttress portion so as to protrude outward in the tire radial direction and continuously extend in the tire circumferential direction, and the protrusion includes a thickness center line of the protrusion and a tire. An angle θ formed with the radial line is 30 ° or less, and a tire radial distance T between the outer end in the tire radial direction of the protrusion and a plane grounded in a normal load state is formed to be 0.5 to 10 mm. . The pneumatic tire having such a protruding portion can prevent noise due to the collision between the tread portion and the road surface at the protruding portion and prevent leakage to the outside. Therefore, the noise performance is improved.

It is sectional drawing which shows the pneumatic tire of one Embodiment of this invention. It is an expanded sectional view near the buttress part. It is a perspective view showing the outer surface of a buttress part. (A) thru | or (c) are sectional drawings showing the projection part of other embodiment of this invention.

  FIG. 1 is a right half sectional view including a tire rotation axis of the pneumatic tire 1 of the present embodiment, and FIG. 2 is an enlarged sectional view of a buttress portion 10 thereof. The cross-sectional views of FIGS. 1 and 2 are in a normal load state in which the tire is assembled on the normal rim J and filled with the normal internal pressure, and a normal load is applied and grounded on a plane. Unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal load state.

  Here, the “regular rim J” is a rim defined for each tire in the standard system including the standard on which the tire is based, and is “standard rim” for JATMA, and TRA for TRA. "Design Rim" or "Measuring Rim" for ETRTO. In addition, the “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "Maximum value", ETRTO, "INFLATION PRESSURE".

  The “regular load” is a load determined by each standard for each tire in a standard system including the standard on which the tire is based. “JATMA” is “maximum load capacity”, and TRA is a table. The maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”. If ETRTO, “LOAD CAPACITY”.

  As shown in FIG. 1, the pneumatic tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment reaches the bead core 5 of the bead portion 4 from the tread portion 2 through the sidewall portion 3. This embodiment includes a carcass 6 and a belt layer 7 disposed radially outside the carcass 6 and inside the tread portion 2. In this embodiment, a pneumatic tire for a passenger car is shown. The tread portion 2 is appropriately provided with a draining groove 9.

  The carcass 6 includes a main body portion 6a straddling a pair of bead cores 5 and 5 in a toroidal shape, and a turn-back portion 6b connected to both sides of the main body portion 6a and folded around the bead core 5 from the inner side to the outer side in the tire axial direction. And at least one carcass ply 6A (in the present embodiment). In the carcass ply 6A, carcass cords made of, for example, organic fibers are arranged at an angle of, for example, 75 to 90 ° with respect to the tire equator C direction. A bead apex rubber 8 extending in a tapered shape from the bead core 5 to the outer side in the tire radial direction of the bead core 5 is disposed between the main body portion 6a and the folded portion 6b, and the bead portion 4 is reinforced.

  The belt layer 7 is composed of at least two belt plies 7A and 7B in the tire radial direction in this embodiment, and the inner belt ply 7A is formed wider than the outer belt ply 7B. The Each of the belt plies 7A and 7B has a highly elastic belt cord such as a steel cord that is inclined with respect to the tire equator C at an angle of 15 to 30 °. The belt plies 7A and 7B are overlapped so that the belt cords cross each other.

  As shown in FIG. 1, the pneumatic tire 1 of the present embodiment has a buttress portion 10 that extends inward in the tire radial direction from the end portions Te on both sides of the tread portion 2. In the present specification, the end portion Te of the tread portion 2 is defined as the ground contact end on the outermost side in the tire axial direction of the pneumatic tire 1 in a normal load state. The buttress portion 10 refers to a region between the end portion Te of the tread portion 2 and the tire maximum width point M where the tire protrudes most outward in the tire axial direction.

  As shown in FIGS. 1 and 2, in the pneumatic tire 1 of the present embodiment, a protruding portion 11 that protrudes outward in the tire radial direction and continuously extends in the tire circumferential direction is formed on the outer surface 10 n of the buttress portion 10. Is done. Such a protrusion 11 can block noise generated by the collision between the tread portion 2 and the road surface R at the protrusion 11 and suppress leakage to the outside of the vehicle. Therefore, the noise performance is improved.

  Further, the protrusion 11 of the present embodiment is tapered (tapered) toward the outer side in the tire radial direction. Such a protrusion 11 can reduce the centrifugal force caused by the rotation of the tire and is excellent in durability.

  Further, as shown in FIG. 2, the protrusion 11 includes an outer surface 11a that forms the outer side in the tire axial direction from the outer end 11x in the tire radial direction of the protrusion 11, and the tire axial direction from the outer end 11x. And an inner side surface 11b forming the inner side. And this inner surface 11b interrupts | blocks the above-mentioned noise.

  Further, the angle θ formed by the center line G1 of the thickness of the protrusion 11 and the tire radial direction line n is set to 30 degrees or less. That is, when the angle θ exceeds 30 degrees, the noise is likely to leak to the outside through the inner side surface 11b of the protruding portion 11, so that the noise suppressing effect cannot be sufficiently obtained. From such a viewpoint, the angle θ is preferably 20 degrees or less, more preferably 5 degrees or less.

  Further, when the protrusion 11 extends inward in the tire axial direction, the inner surface 11b of the protrusion 11 and the outer surface 10n of the buttress 10 are easily connected at an acute angle, and the intersection of the inner surface 11b and the outer surface 10n. In the vicinity of K3, cracks and chips are likely to occur. From such a viewpoint, it is desirable that the protrusion 11 extends outward in the tire axial direction.

  Further, a tire radial distance T between the outer end 11x of the protrusion 11 in the tire radial direction and the plane h grounded in a normal load state is set to 0.5 to 10 mm. When the tire radial direction distance T is less than 0.5 mm, the protrusion 11 is likely to come into contact with the road surface R, and noise generated by this contact may deteriorate the noise performance. Further, due to the contact with the road surface R, the protrusion 11 may be chipped or cracked, and the durability of the protrusion 11 may be deteriorated. On the other hand, when the tire radial distance T exceeds 10 mm, the protrusion 11 cannot prevent noise leakage. From such a viewpoint, the distance T is preferably 1 mm or more, more preferably 2.0 mm or more, and preferably 5 mm or less, more preferably 4.0 mm or less.

  On the other hand, if the length L of the protrusion 11 is too large, an increase in the weight of the tire or chipping of the protrusion 11 due to its own weight tends to occur, which may deteriorate durability. Conversely, if the length L is too small, there is a tendency that noise leakage cannot be prevented. From such a viewpoint, the length L is preferably 3 mm or more, more preferably 5 mm or more, and preferably 10 mm or less, more preferably 7 mm or less. The length L of the protrusion 11 is, as shown in FIG. 2, an intersection K1 between the center line G1 and a virtual buttress surface 10x that smoothly connects the outer surfaces other than the protrusions of the buttress 10; It is defined as the actual length of the center line G1 between the center line G1 and the intersection K2 of the outer surface 11n of the protrusion 11.

  Further, when the position of the intersection K1 is too close to the plane h, the protrusion 11 tends to have a length L of the protrusion 11 and the inner side surface 11b that are difficult to block noise. On the contrary, if the position of the intersection K1 is far from the plane h, the length of the protrusion 11 is increased, which may increase the weight or deteriorate the durability due to its own weight. From this point of view, the position of the intersection point K1 is preferably 10% or more, more preferably 15% or more, and preferably 30% or less, more preferably 20% of the tire cross-section height H from the plane h. The following is desirable.

  Further, if the thickness W of the protrusion 11 is too large, the weight of the tire tends to increase. Conversely, if the thickness W is too small, the durability of the protrusion 11 tends to deteriorate. From such a viewpoint, the thickness W is preferably 3 mm or more, more preferably 4 mm or more, and preferably 10 mm or less, more preferably 7 mm or less. When the thickness W of the protruding portion 11 varies over the length L of the protruding portion 11, the thickness measured at a midpoint 11c of the length L in a direction perpendicular to the center line G1. Say it.

  The inner side surface 11b is preferably provided with a silencer that can reduce noise itself. Thereby, when the noise generated in the tread portion 2 propagates outward in the tire axial direction, the noise reduction portion reduces the noise. Accordingly, such a pneumatic tire 1 not only prevents noise leakage but also can reduce noise by absorbing and attenuating the noise itself, thereby further improving noise performance. As such a silencer, for example, in addition to a porous material having a large number of pores on the surface (for example, sponge or foam rubber), a large number of dimples 12 such as dimples that increase the surface area of the inner surface 11b ( (Shown in FIG. 3) is effective.

  The diameter d of the recess 12 is, for example, 0.5 mm or more, preferably 1 mm or more, more preferably 1.5 mm or more, and more preferably 3 mm or less, in order to effectively exhibit the sound absorption effect. Is preferably 2.5 mm or less. Similarly, the depth (not shown) of the recess 12 is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 3 mm or less, more preferably 2.5 mm or less.

  FIG. 4 (a) shows another shape of the protrusion 11 as another embodiment of the present invention. In the protrusion 11 of this embodiment, an inward bent portion 13 that is bent inward in the tire axial direction is formed on the distal end side of the protrusion 11. As shown in FIG. 2, the inner side surface 11 b of the protruding portion 11 faces the inner side in the tire axial direction as compared to the inner side surface 11 b of the protruding portion 11 that extends straight. For this reason, it becomes easy to interrupt | block the said noise leaking outside, and noise performance improves further.

  When the center line G1 of the protrusion 11 is not formed as a straight line as in the present embodiment, the angle θ is an angle between the straight line GA connecting the intersection point K1 and the intersection point K2 and the tire radial direction line n. Is defined as

  FIG. 4B shows another shape of the protrusion 11 as still another embodiment of the present invention. Since the protruding portion 11 of this embodiment is formed with an outward bent portion 14 that bends outward in the tire axial direction on the distal end side of the protruding portion 11, the surface area of the inner side surface 11 b of the protruding portion 11 is increased. Such a pneumatic tire 1 can increase the blocking effect and further improve the noise performance.

  FIG. 4C shows another shape of the protrusion 11 as still another embodiment of the present invention. In the protrusion 11 of this embodiment, an inward bent portion 13 that is bent inward in the tire axial direction and an outward bent portion 14 that is bent outward in the tire axial direction are formed on the distal end side of the protrusion 11. Since such a pneumatic tire has the above-described effects, the noise performance is further effectively improved.

  As a manufacturing method of the pneumatic tire 1 as described above, the protruding portion 11 may be formed by vulcanization molding of a tire according to a conventional method, or the protruding portion 11 is formed on the buttress portion 10 of the vulcanized pneumatic tire. It may be glued.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

  In order to confirm the effect of the present invention, a pneumatic tire for a passenger car of size 175 / 65R15 having the internal structure of FIG. 1 was prototyped based on the specifications of Table 1 and tested for noise performance and durability performance. . All the structures other than the protrusions are the same. The main specifications are as follows.

Tread width TW: 135mm
Number of carcass plies: 1 carcass cord angle: 90 °
Carcass cord material: Polyethylene terephthalate Number of belt plies: 2 Belt cord angle: 24 °
Belt cord material: Steel cord Rim: 5.5 × 15J
Internal pressure: 200 kPa
The road surface temperature during the test was 42 ° C.
The test method is as follows.

<Noise test>
In accordance with the actual vehicle coasting test specified in JASO / C / 606, the vehicle travels on a straight test course (asphalt road surface) at a speed of 50 m at a passing speed of 60 km / h, and from the traveling center line at the midpoint of the course. The maximum level of passing noise dB (A) was measured with a stationary microphone installed at a position of 7.5 m on the side and 1.2 m from the road surface. A result is displayed by the index | exponent which makes the reciprocal number of the comparative example 1 100, and shows that passing noise is so small and favorable that an index | exponent is large.

<Durability test>
Each test tire was mounted on a rim, and after running a drum of 1.7 m in diameter at a speed of 60 km / h at a speed of 606 kg (120% of the standard load of JATMA), the damaged state of the protrusion was observed with the naked eye. . The results were evaluated as ◯ for those that were not damaged, Δ for those that were damaged by cracks, and × that were damaged by chips.
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that the example has better noise performance and durability performance than the comparative example. Moreover, in the noise measurement, although the passing speed was measured at 40 and 80 km / h at the same time, the same test results as in the case of 60 km / h were shown.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 10 Buttress part 10n Buttress part outer surface 10x Virtual buttress surface 11 Protrusion part 11x Tire radial direction outer end G1 Centerline h of protrusion part thickness h A normal load was loaded and grounded Plane T Tire radial direction distance Te between the tire radial direction outer end and the flat surface Tire tread end θ The angle formed by the thickness center line of the projection and the tire radial line

Claims (5)

A pneumatic tire having a tread portion and a buttress portion extending inward in the tire radial direction from both ends thereof,
On the outer surface of the buttress portion is formed a protrusion that protrudes outward in the tire radial direction and extends continuously in the tire circumferential direction,
In a tire meridian cross section including a tire rotating shaft in a normal load state that is mounted on a normal rim and is filled with a normal internal pressure and is loaded with a normal load and grounded to a plane with a camber angle of 0 °,
The protrusion has an angle θ formed by a center line of the thickness of the protrusion and a tire radial direction line of 30 degrees or less, and a tire radial distance T between the tire radial outer end of the protrusion and the plane. A pneumatic tire characterized by having a diameter of 0.5 to 10 mm.   The pneumatic tire according to claim 1, wherein the angle θ is 20 degrees or less.   The pneumatic tire according to claim 1 or 2, wherein the tire radial distance T is 1 to 5 mm.   In the protrusion, an intersection of the center line and a virtual buttress surface smoothly connecting outer surfaces other than the protrusion of the buttress portion is formed at a position of 10 to 30% of the tire cross-sectional height from the plane. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein the protruding portion is tapered toward the outer side in the tire radial direction.

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