JP4119686B2 - Pneumatic tire - Google Patents

Description

表１の結果が示すように、本発明によると、低周波ロードノイズの低減効果と操縦安定性の改善効果とを両立させることができる。これに対し、コード角が小さく角度差がない比較例２では、低周波ロードノイズの低減効果が若干得られるものの、操縦安定性の改善効果が全く得られなかった。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一例を示す部分断面図
【図２】図１の空気入りタイヤの要部を示す図であり、（ａ）はカーカス層を模式的に示す側面図、（ｂ）はそのコードの配置を模式的に示す説明図
【図３】本発明の空気入りタイヤの他の例の要部を示す図であり、（ａ）はカーカス層を模式的に示す側面図、（ｂ）はそのコードの配置を模式的に示す説明図
【図４】カーカス用プライの作製に用いられる装置の概略斜視図
【符号の説明】
１ａ ビード
１ｂ ビードフィラー
１０ カーカス層
１３ 内側カーカス層の本体部
１４ 外側カーカス層の本体部
１５ 内側カーカス層の巻き返し部
１５Ａ 先端側の部分
１５Ｂ ビードフィラーに隣接配置された部分（傾斜部）
１５ａ 先端側のコード
１５ｂ ビードフィラーに隣接配置された部分のコード
１６ 外側カーカス層の巻き返し部
１６ａ 巻き返し部のコード
Ｈ タイヤ断面高さ
ＰＤ タイヤ周方向
ＲＤ タイヤ半径方向
θ₁ 〜θ₃ コード角
θ₄ コード角の差[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire including a pair of annular beads and a two-layer carcass layer wound at both ends by the beads.
[0002]
[Prior art]
Currently, radial tires, which are the mainstream of pneumatic tires, reinforce a space between a pair of annular beads, and a carcass layer in which a plurality of cords are arranged in the tire radial direction (meridian direction), and a carcass located below the tread. A structure including a plurality of belt layers in which the layers are reinforced by the hoop effect and the cords are inclined with respect to the tire circumferential direction is common. Further, both end portions of the carcass layer are wound back to the outside by beads, and the cords of the wound portions are usually arranged in the tire radial direction.
[0003]
Various types of pneumatic tires are known in which a reinforcing layer reinforced with long fibers or short fibers is provided in addition to the carcass layer around the bead for the purpose of improving the handling stability by increasing the rigidity of the bead portion. ing. There is also known a pneumatic tire in which the rigidity of the bead portion is increased by inclining the cord of the winding portion of the carcass layer from the tire radial direction without providing such a reinforcing layer (Japanese Patent Laid-Open No. 11-170807). No., JP-A-8-324213, etc.). Further, there is a type in which the rigidity of the sidewall portion is increased by increasing the tip of the winding portion of the carcass layer.
[0004]
On the other hand, when the vehicle travels on a relatively rough road surface, noise called road noise is generated in the passenger compartment. This road noise is one of the noises related to tires, and the tires vibrate due to the road surface unevenness being input to the tires, and this vibration is transmitted along the propagation path such as the axle, suspension, and vehicle body, and finally Cause noise in the passenger compartment. Of this vehicle interior noise, low-frequency road noise generated in the vicinity of 125 Hz is close to the primary resonance frequency of the tire and coincides with that frequency, resulting in a road noise peak. Therefore, noise reduction is required.
[0005]
[Problems to be solved by the invention]
However, it has been found that when the rigidity of the bead portion or the sidewall portion is increased as described above, the low frequency road noise generally increases, and the cause thereof is due to the change in the primary resonance frequency of the tire. Further, in the above-described tire in which the cord of the winding portion of the carcass layer is inclined from the radial direction, the effect of improving the rigidity with respect to the longitudinal force at that portion can be obtained, but the primary resonance frequency of the tire is suitably controlled. In addition, it was difficult to say that the effect of reducing low-frequency road noise was sufficient. In other words, improving the steering stability by increasing the rigidity of the bead part and reducing the low-frequency road noise are contradictory phenomena, and the technology that aims to achieve both is focused on the change in the primary resonance frequency. Never existed before.
[0006]
Accordingly, an object of the present invention is to provide a pneumatic tire that can achieve both the effect of reducing low-frequency road noise and the effect of improving steering stability.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the inventors of the present invention have made extensive studies on a method of reducing the primary resonance frequency while improving the steering stability, and while tilting the cord of the winding portion of at least one carcass layer from the radial direction, It has been found that the effect of reducing low-frequency road noise and improving the steering stability can be achieved by making the angle formed by the cords of the two rewinding portions more than a certain value, and the present invention has been completed.
[0008]
That is, the pneumatic tire of the present invention, a bead of a pair of annular, in the pneumatic tire and a carcass layer consisting of two layers having both ends rolled back in its bead, both the carcass layer of the rewinding section of the bead filler portion disposed along the forms code angle between cord and the tire circumferential direction and having respective constant or angle change ramps to within the range of 30 to 85 °, one of those of the inclined portion code of the inclined portion of state, and are angle 5 ° or more formed by the code of the other inclined portion, the inclined portion and the other rewinding portion adjacent to the inclined portion, on the same side with respect to the tire radial direction The cord is inclined.
[0011]
[Function and effect]
According to the present invention, since the cord has an inclined portion in the portion that is disposed adjacent to the bead filler in the winding portion of at least one of the carcass layers, the rigidity (vertical rigidity) with respect to the longitudinal force (force in the vertical direction) is increased. This can lower the primary resonance frequency of the tire. At this time, since the angle formed by the cord of the inclined portion and the other winding portion adjacent to the inclined portion is more than a certain value, a sufficient reinforcing effect can be obtained by crossing the two cords. The rigidity (lateral rigidity and longitudinal rigidity) can be increased. In particular, both the carcass layers have an inclined portion, and the cord of one inclined portion has an angle formed with the cord of the other inclined portion of 5 ° or more, compared with the case where only one has the inclined portion. Accordingly, the effect of reducing the longitudinal rigidity and the effect of improving the lateral rigidity are further increased, and it becomes easier to achieve both the effect of reducing the low-frequency road noise and the effect of improving the steering stability. As a result, it is possible to provide a pneumatic tire that can achieve both an effect of reducing low-frequency road noise and an effect of improving steering stability. In addition, the cord is inclined on the same side with respect to the tire radial direction between the inclined portion and the other rewinding portion adjacent to the inclined portion. However, since the effect is reduced, the longitudinal rigidity can be further reduced as compared with the case of inclining to the opposite side, and thereby the primary resonance frequency of the tire can be reduced.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing an example of a pneumatic tire of the present invention, FIG. 2 (a) is a side view schematically showing the carcass layer, and FIG. 2 (b) is a schematic arrangement of cords in the carcass layer. FIG.
[0015]
As shown in FIG. 1, the pneumatic tire according to the present invention includes a pair of annular beads 1 a and two carcass layers 10 having both ends rolled back by the annular beads 1 a. The inner carcass layer is composed of the main body portion 13 and the winding portion 15, and the outer carcass layer is composed of the main body portion 14 and the winding portion 16. The pneumatic tire has a cross-sectional structure that is symmetric or substantially symmetric with respect to the equator line CL.
[0016]
As for the main-body parts 13 and 14 between the beads 1a of the carcass layer 10, as shown in FIG. 2, it is preferable that the cord angle made by the cord and the tire circumferential direction PD is 85 to 90 °. This point is the same as that of a normal radial tire, and in combination with the belt layer 6, the riding comfort, durability, exercise performance, and the like of the radial tire can be suitably expressed. Examples of the cord constituting the carcass layer 10 include organic fibers such as rayon, polyester, polyamide, and aromatic polyamide, or steel.
[0017]
The belt layer 6 can be exemplified by a two-layer configuration of an upper layer 6b and a lower layer 6a, but the angle of the cords constituting each layer with respect to the tire equator line CL is preferably 10 to 35 °. Moreover, you may provide the fiber reinforcement layer which has arrange | positioned the cord further in the circumferential direction on the upper surface of the upper layer 6b. As the cord material constituting the belt layer 6, any of the materials conventionally used for the belt layer 6 such as steel and organic fibers such as aromatic polyamide can be used.
[0018]
In the present invention, as shown in FIG. 2, the winding portion 15 of the inner carcass layer is distinguished into a portion 15B (region of height H1) disposed adjacent to the bead filler 1b and a portion 15A on the tip side from the portion 15B. Is done. In the present invention, the portion 15B has an inclined portion that is constant or changes in angle within the range of the cord angle θ ₃ = 30 to 85 °. In the present embodiment, an example in which the inclined portion coincides with the portion 15B and the portion 15A is inclined at the same cord angle θ ₂ as the portion 15B is shown.
[0019]
If this way is an inclined portion cord angle theta ₃ of constant code 15b code angle theta ₃ of it is preferably constant within a range of 45 to 85 ° (or angle change things). This is the same when the cord angle θ ₃ changes. The cord angle θ ₂ of the cord 15a of the portion 15A is preferably 30 to 90 °.
[0020]
The height H1 of the portion 15B of the rewinding portion 15 is 20 to 50% of the tire cross-section height H in order to achieve both the low-frequency road noise reduction effect and the steering stability improvement effect. Is preferable, and the height is more preferably 40 to 50%. Further, the width of the inclined portion is preferably 70% or more of the portion 15B, more preferably 90% or more. In addition, although the position of the front-end | tip of the winding-up part 15 may be higher or lower than the position PW of the tire maximum width W, the higher one is preferable because the effect of the inclined part becomes larger.
[0021]
In the present invention, it is sufficient that at least one of the carcass layers has the inclined portion as described above, but it is preferable that both carcass layers have the inclined portion as described above. In this embodiment, the latter example is shown.
[0022]
That is, as shown in FIG. 2, the winding portion 16 of the outer carcass layer also has an inclined portion 16B that is constant or changes in angle within the range of the cord angle θ ₁ = 30 to 85 °. In the present invention, the angle formed by the cord 16b of the inclined portion 16B and the cord 15b of the inclined portion of the rewinding portion 15 is 5 ° or more, preferably 10 ° or more. When this angle is less than 5 °, the shear strain hardly occurs between the inclined portion 16B and the portion 15B, and the reinforcing effect by both layers becomes insufficient.
[0023]
And it is preferable that the cord 15b, 16b inclines in the same side with respect to tire radial direction RD with respect to the inclination part of the winding-back part 15, and the other winding-back part 16 adjacent to the inclination part.
[0024]
The height H2 of the rewinding portion 16 is preferably 45 to 55% of the tire cross-section height H in order to enhance the steering stability improving effect by improving the lateral rigidity. In addition, the relationship between the height of the front end of the rewinding portion 15 and the height H2 of the rewinding portion 16 is lower than the height H2 from the viewpoint of preventing separation of the front end of the rewinding portion 16 and improving the durability of the tire. It is preferable.
[0025]
The pneumatic tire of the present invention preferably has a primary resonance frequency of 120 Hz or less measured from an axial force response in the vertical direction due to hammer vibration applied to a tire loaded in an air-filled state.
[0026]
Such a primary resonance frequency can be adjusted by the cord angle, width, cord material, thickness, number of driving, number of carcass layers 10, hardness, shape, size, etc. of the bead filler 1 b of the inclined portion. . By adjusting these and reducing the lateral rigidity, the primary resonance frequency can be lowered. The bead filler 1b has a hardness (after vulcanization) of 80 to 98 ° in terms of JISA hardness.
[0027]
In the present embodiment, as shown in FIG. 1, a chacher 21 that reinforces the outside of the carcass layer 10 around the bead is provided. As the chacher 21, a rubber whose hardness is increased or a rubber reinforced with long fibers or short fibers can be used.
[0028]
Except for the above points, the tire has substantially the same structure as a normal radial tire. That is, as shown in FIG. 1, both ends of the carcass layer 10 are folded back by the bead 1a, and the bead filler 1b having a high rubber hardness is provided between the winding portions 15 and 16 and the main body portions 13 and 14 of the carcass layer 10. The bead portion 1 is formed. Similarly to the normal tire, the side wall rubber 2 a is disposed outside the carcass layer 10, the inner liner rubber 3 is disposed inside, and the tread rubber 4 is disposed outside the belt layer 6. A predetermined pattern is formed on the outer peripheral surface.
[0029]
Examples of the raw rubber for the rubber layer include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), and butyl rubber (IIR). These rubbers are reinforced with fillers such as carbon black and silica, and a vulcanizing agent, a vulcanization accelerator, a plasticizer, an antiaging agent, and the like are appropriately blended. In addition, a steel wire or the like is used as the bead wire, and surface treatment or adhesion treatment is usually performed in order to improve adhesion to rubber.
[0030]
The pneumatic tire of the present invention can be manufactured by the same manufacturing method as that of a normal pneumatic tire except that a carcass ply in which the cord angle of the winding portion of the carcass layer is partially changed from the tire radial direction is used. The carcass ply is formed into a cylindrical shape. For example, after a bead is disposed, a tubular airbag is inserted and shaped into a donut shape by internal pressure, and then a belt layer is formed by a conventional method.
[0031]
The carcass ply uses, for example, a device in which the tip of the cord is attached to the tray in a desired path by a driving application roller while supplying a rubber-coated cord, or JP-A-8-244135. In the manufacturing method described in the publication, it can be produced by changing the cord angle of the carcass ply.
[0032]
The method for forming the carcass ply using the former apparatus will be further described as follows. That is, by using the apparatus as shown in FIG. 4 to pull the cord material 40 by the roller group 43, while passing the cord material 40 from the bobbin 41, the cord material 40 is passed through the base portion 42a of the coated rubber extruder 42 and is not yet passed. The cords covered with vulcanized rubber and covered with rubber are sent between the buffer rollers 44a of the buffer portion 44 and become loose. The tip of the rubber-coated cord is attached to the tray 47 in a desired path by an attaching roller 46c provided in the drive unit 46b of the drive mechanism 46, and the length of the cord corresponding to the amount of attachment is the buffer unit 44. Is taken through the guide roller 45. The pasting path is controlled by position control of movement of the tray 47 in the longitudinal direction (Y direction) and position control of movement of the drive part 46b reciprocating the support part 46a of the drive mechanism 46 (X direction). Can do. Thereby, the carcass ply 48 can be produced on the tray 47. Affixing is easy to perform without cutting the cord, and in this case, two affixing rollers 46c having parallel axes and the same height are used.
[0033]
In order to obtain a desired tire shape and a desired cord angle at each part, it is preferable to appropriately adjust the cord angle when the carcass ply is manufactured. In the bias tire, the relationship between the cord angle in the ply state and the cord angle after the tire molding can be calculated by the following well-known relational expression (approximate expression). However, in the present invention, the relational expression can be similarly applied. A can be obtained by determining R of the corresponding part using as a variable.
[0034]
Rd cosA = R cosAd
Here, Rd is a drum radius, Ad is a cord angle with respect to the circumferential direction on the drum, R is a radius corresponding to the position of the cord after tire molding, and A is a cord angle with respect to the circumferential direction after tire molding. In the present invention, the carcass ply produced in this way is used by being laminated in two layers.
[0035]
[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described.
[0036]
(1) In the above-described embodiment, the example in which the tip side portion of the winding portion of the inner carcass layer has the same cord angle as the inclined portion is shown. However, in the present invention, the tip side portion is different from the inclined portion. It may be a corner. Moreover, although the code | cord | chord also inclined the outer part of the circumference | surroundings of a bead, the code | cord | chord of the part of the circumference | surroundings of a bead may be arrange | positioned radially.
[0037]
(2) In the above-described embodiment, an example in which the winding portions of both carcass layers have a constant cord angle has been described. However, in the present invention, the winding portions of either or both carcass layers change in angle. May be. For example, as shown in FIG. 3, the cord angle θ ₁ of the winding portion 16 of the carcass layer and the cord angle θ ₃ of the winding portion 15 of the carcass layer may be changed. In that case, the portions 15B and 16B adjacent to the bead filler 1b in the winding portions 15 and 16 of the carcass layer are gradually reduced toward the tip side in an angle range in which the cord angle θ ₃ is in the range of ₃₀ to 85 °. It is preferable to have an inclined portion. Thus, the cord angle when the cord angles θ ₃ and θ ₁ change is determined by the cord angle formed by the tangent to the cord and the tire circumferential direction PD. The angle formed by the two cords is determined by the angle θ ₄ of the tangent at the portion where the cords intersect.
[0038]
(3) In the above embodiment, the cord angle θ ₁ is larger than the cord angle θ _3. However, the cord angle θ ₁ of the cord 16b of the winding portion 16 of the outer carcass layer is equal to the cord angle θ of the inclined portion. _It may be smaller than ₃ . Also in this case, the difference between the code angle θ ₁ and the code angle θ ₃ is 5 ° or more. When the code angle θ ₃ changes as shown in FIG. The difference between the angle θ ₁ and the cord angle θ ₃ is preferably 5 ° or more.
[0039]
(4) In the above-described embodiment, an example in which the portion of the winding-up portion that is disposed adjacent to the bead filler coincides with the inclined portion, but in the present invention, the winding-up portion includes a portion other than the inclined portion, that is, a cord. A part where the angle is 85 to 90 ° or a part less than 30 ° may be included.
[0040]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the measurement of physical properties and performance evaluation in Examples and the like were performed as follows.
[0041]
(1) Based on a graph in which a lateral force is applied and a lateral force-lateral deflection relationship is measured in a state where the air pressure of the lateral rigid tire is 210 KPa and the load load is 510 Kg, the load load (510 Kg) The lateral force corresponding to 0.3 times the value was calculated by dividing by the lateral deflection when the force was applied.
[0042]
(2) Primary resonance frequency With the tire pressure set to the specified air pressure (210 KPa) and load load (510 Kg), hammer vibration in the vertical direction is applied to the center of the tread on the outer peripheral surface of the tire. The response in the vertical direction generated on the shaft is displayed for each frequency at the vibration transmission level. Of the plurality of natural vibration peaks generated at that time, the frequency of the peak that appears first from the lowest frequency was defined as the primary resonance frequency (primary elastic mode frequency).
[0043]
(3) Steering stability Pneumatic tires of size 205 / 55R16 89V obtained in the working examples and the like were mounted on an actual vehicle (2000cc class domestic sedan) with a rim assembly (rim: 6.5J) at an air pressure of 220 kPa. With this actual vehicle, an actual vehicle feeling test (straight ahead, lane change, handling stability) was performed on the test course when dry, and the results were evaluated with an index of 100 as the conventional product. The larger this value, the better the maneuverability.
[0044]
Example 1
The cord is rayon (1840 dtex / 2, stress 44N / stretch when elongation is 2%), the carcass ply has two layers of 48/5/5 cm, a bead filler forming member (JISA hardness 92 ° after vulcanization, Using a triangular cross section with a base of 8 mm and a height of 45 mm, the main body portion gradually increases from 90 ° to cord angle, and the winding portion (filler side inclined portion) gradually increases from 30 ° to 85 ° cord angle. Part) is formed with two carcass layers wound outward with beads so that the cord angle gradually increases from 20 ° to 75 °, and the other portions are the same as in a normal radial tire, as shown in FIG. A pneumatic tire having a tire size of 205 / 55R16 89V was manufactured.
[0045]
Example 2
Using the same carcass ply and bead filler forming member as in Example 1, the main body portion is gradually reduced from 90 ° to the cord angle, and the turned-up portion (filler side inclined portion) is gradually reduced from the cord angle of 85 ° to 30 °. A two-layer carcass layer wound outward with a bead is formed so that the (outer inclined portion) gradually decreases from a cord angle of 75 ° to 20 °, and the other portions are the same as in a normal radial tire. A pneumatic tire having a tire size of 205 / 55R16 89V as shown in FIG.
[0046]
Example 3
Using the same carcass ply and bead filler forming member as in Example 1, the main body portion has a cord angle of 90 °, the rewinding portion (filler side inclined portion) has a constant cord angle of 60 °, and the rewinding portion (outer inclined portion) Two carcass layers wound outward with beads to form a constant cord angle of 70 ° are formed, and the other portions are the same as a normal radial tire, and the tire size 205 / 55R16 89V as shown in FIG. Prototype of pneumatic tires.
[0047]
Comparative example 1 (conventional product)
In Example 1, all the folded portions of the two carcass layers are formed with a cord angle of 90 ° (the cord is radial at all positions), and the other portions are the same tires as in the case of a normal radial tire. Trial tires were made.
[0048]
Comparative Example 2
In Example 1, the same tire size as in Example 1 except that the cord angle of the rolled-up portion of the two carcass layers was 29 ° and the JISA hardness after vulcanization of the bead filler forming member was 92 °. Prototype of pneumatic tires.
[0049]
Table 1 shows the results of the evaluation using the above pneumatic tires.
[0050]
[Table 1]

As shown in the results of Table 1, according to the present invention, it is possible to achieve both the effect of reducing low-frequency road noise and the effect of improving steering stability. On the other hand, in Comparative Example 2 in which the cord angle is small and there is no angle difference, although the effect of reducing the low-frequency road noise is slightly obtained, the effect of improving the steering stability is not obtained at all.
[Brief description of the drawings]
1 is a partial cross-sectional view showing an example of the pneumatic tire of the present invention. FIG. 2 is a view showing a main part of the pneumatic tire of FIG. 1, wherein (a) is a side view schematically showing a carcass layer. (B) is an explanatory view schematically showing the arrangement of the cords. FIG. 3 is a view showing a main part of another example of the pneumatic tire of the present invention, and (a) is a side view schematically showing a carcass layer. FIG. 4B is an explanatory diagram schematically showing the arrangement of the cords. FIG. 4 is a schematic perspective view of an apparatus used for manufacturing a carcass ply.
DESCRIPTION OF SYMBOLS 1a Bead 1b Bead filler 10 Carcass layer 13 Inner carcass layer main body part 14 Outer carcass layer main body part 15 Inner carcass layer rewinding part 15A Front end part 15B Part adjacent to bead filler (inclined part)
15a Lead-side cord 15b Cord 16 disposed adjacent to the bead filler 16 Outer carcass layer rewinding portion 16a Rewinding portion cord H Tire cross-section height PD Tire circumferential direction RD Tire radial direction θ _{1 to} θ ₃ Cord angle θ ₄ Cord angle difference

Claims (1)

In a pneumatic tire comprising a pair of annular beads and a carcass layer composed of two layers whose ends are rolled back by the beads,
Both the carcass layer is disposed portions along the bead filler of the rewinding section, respectively inclined portion formed cord angle a cord and the tire circumferential direction is constant or angular change within a range of 30 to 85 ° together with, one code of the inclined portion of those ramps state, and are code angle between the 5 ° or more other inclined portion, the inclined portion and the other rewinding portion adjacent to the inclined portion A pneumatic tire characterized in that the cord is inclined on the same side with respect to the tire radial direction.

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