JP2009280123A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire advantageous in improving quietness of a tire. <P>SOLUTION: Provided is a chafer 28 which wraps a part of a carcass ply 12 along a bead heel and a bead toe of a bead part 13 and abuts on a rim R. The chafer 28 comprises: a plurality of organic fiber cords with a vibrational absorption property (high viscosity); and a coat rubber coating the organic fiber cords. The organic fiber cord with the vibrational absorption property consists of, for example, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), POK (polyolefin ketone), or acrylic. The loss factor tanδ of the coat rubber at 20°C is not less than 0.25. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that is advantageous in improving quietness.

Along with the higher grade and higher performance of cars, tires are required to have quietness in addition to basic motion performance. In particular, with the spread of hybrid cars as environmentally conscious cars, tires are required to be more quiet.
Conventionally, as a technique for realizing quietness, a tread pattern and a belt cover material have been devised (Patent Documents 1 and 2).
JP 2007-153239 A JP-A-8-295104

However, there has been a limit in improving the quietness of the tire only with the tread pattern and the belt cover material.
The present inventor has been devised in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire that is advantageous in improving the quietness of the tire.

  In order to achieve the above object, according to the present invention, a carcass ply is mounted on a bead core of a pair of left and right bead parts, and a portion of the carcass ply along a bead toe is wrapped from a bead heel of the bead part so as to be able to contact the rim. A fur is provided, and the chafer is a pneumatic tire configured to include an organic fiber cord, and the organic fiber cord is a material having vibration absorption performance.

  According to the present invention, since the organic fiber cord constituting the chafer has vibration absorption performance, transmission of vibration can be effectively suppressed between the tire and the rim, which is advantageous in improving quietness. Become.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a meridian cross-sectional view of a pneumatic tire.
The pneumatic tire 10 includes a carcass ply 12 that forms a skeleton on the inner side of the tire, an annular bead core 14 and a bead filler 16 that are embedded in a pair of left and right bead portions 13 and wrapped around a folded portion of the carcass ply 12, and a carcass in a tread portion. A belt layer 18, a side wall rubber 22, a tread rubber 24, an inner liner 26, and the like attached to the outside of the ply 12 are included.
In the present embodiment, the bead core 14 is composed of a plurality of steel cords, but the bead core 14 can employ various known structures.
Both ends of the carcass ply 12 are folded around the bead core 14 from the inner side to the outer side in the tire width direction.
Therefore, the carcass ply 12 is mounted on the bead core 14 of the pair of left and right bead portions 13.

FIG. 2 shows an enlarged cross-sectional view of the bead portion 13.
In FIG. 2, reference numeral 28 denotes a chafer that wraps around a portion of the carcass ply 12 along the bead toe from the bead heel of the bead portion 13 and can contact the rim R.
The chafer 28 is composed of a plurality of (highly viscous) organic fiber cords having vibration absorption performance and a coat rubber that covers these organic fiber cords.
The organic fiber cord having vibration absorbing performance is made of, for example, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), POK (polyolefin ketone), or acrylic.
In the present embodiment, the chafer 28 includes an organic fiber cord having vibration absorption performance, and usually has a higher loss factor tanδ than nylon used for the chafer. Therefore, the tire 10 and the rim R This is advantageous in suppressing the transmission of vibration between the two and improving quietness.

Further, the loss coefficient tan δ at 20 ° C. of the coated rubber covering the organic fiber cord is 0.25 or more and 0.40 or less.
The loss coefficient tan δ at 20 ° C. of the coated rubber is preferably 0.25 or more and 0.40 or less for enhancing durability while enhancing the vibration suppressing effect.
If the loss coefficient tan δ is less than 0.25, it is disadvantageous in securing the vibration suppressing effect, and if it exceeds 0.40, there is a disadvantage that durability is lowered due to heat generation due to repeated deformation.
By covering the organic fiber cord with such a coat rubber, vibration transmission between the tire 10 and the rim R can be further suppressed.
Conventionally, some rubbers having a high loss coefficient tan δ are arranged as a gum finishing from the bead heel to the bead toe, but there is a disadvantage in improving cut resistance.
On the other hand, when the organic fiber cord having vibration absorption performance and the above-described coat rubber are arranged as in the present embodiment, it is advantageous in enhancing the vibration suppressing effect while maintaining the cut resistance of the bead portion 13. .

Further, a rim cushion rubber 30 is disposed at a location where the rim R contacts the bead heel of the bead portion 13 from the bead heel.
The loss coefficient tan δ at 20 ° C. of the rim cushion rubber 30 is 0.25 or more and 0.40 or less, and the height a from the outermost rim diameter position in the tire radial direction of the rim cushion rubber 30 is the rim flange height. It is 1.0 times or more and 2.0 times or less of b.
Providing such a rim cushion rubber 30 is even more advantageous in suppressing the transmission of vibration at the portion where the tire 10 and the rim R are in contact with each other and improving quietness.
The loss coefficient tan δ at 20 ° C. of the rim cushion rubber 30 is preferably 0.25 or more and 0.40 or less from the viewpoint of enhancing durability while enhancing the effect of suppressing vibration transmission.
Further, if the loss coefficient tan δ at 20 ° C. of the rim cushion rubber 30 is less than 0.25, there is a disadvantage in suppressing vibration transmission, and if it exceeds 0.40, the disadvantage that durability is deteriorated due to heat generation. There is.
Further, if the height a from the outermost rim diameter position in the tire radial direction of the rim cushion rubber 30 is less than 1.0 times the rim flange height b, it is disadvantageous for suppressing vibration, and 2.0 times. If it exceeds, there is a disadvantage that the durability is lowered due to the occurrence of cracks during repeated deformation.

Further, the chafer 28 is constituted by using a woven fabric constituted by the organic fiber cord.
The warp angle of the fabric is 45 degrees or more and 75 degrees or less with respect to the tire circumferential direction.
As described above, by using the organic fiber cord as a woven fabric, it is possible to improve the reinforcing effect of the chafer 28 such as cut resistance.
Since the chafer 28 is subjected to a large compression and tensile stress, if the warp angle is less than 45 degrees with respect to the tire circumferential direction, there is a disadvantage that a large stress acts on the warp.
In addition, when the warp angle exceeds 70 degrees, there is a disadvantage that irregularities are easily formed on the tire surface.

The fineness of the organic fiber cord is 250 to 800 dtex, and the sum of the warp cover factor CFv calculated from the following formula (1) and the weft cover factor CFh calculated from the following formula (2) is 1000 to 3000. It is as follows.
CFv = Nv · (Sv) ^1/2 (1)
CFh = Nh · (Sh) ^1/2 (2)
However, Nv: Warp density (1 / 5cm)
Nh: Weft density (1 / 5cm)
Sv: warp fineness (dtex)
Sh: Weft fineness (dtex)
When the fineness of the organic fiber cord is less than 250 dtex, there is a disadvantage in securing the reinforcing effect of the chafer 28, and when it exceeds 800 dtex, there is a disadvantage that the air permeability becomes high.
If the sum of the cover factors CFv and CFh is less than 1000, there is a disadvantage that the wear resistance and durability are lowered. If it exceeds 3000, the organic fiber cord becomes too dense, and the adhesion between the organic fiber cord and the coat rubber is lowered. There are disadvantages to doing.
Further, the sum of the warp cover factor CFv and the weft cover factor CFh is preferably 1500 or more and 2000 or less, from the viewpoint of ensuring the adhesion between the organic fiber cord and the coat rubber while ensuring the wear resistance and durability. .

Moreover, the twist coefficient of the said organic fiber cord is 100-500.
Further, if the twist coefficient of the organic fiber cord is less than 100, there is a disadvantage that the adhesion between the organic fiber cord and the coat rubber deteriorates. If it exceeds 500, the dip used for bonding the coat rubber and the organic fiber cord. There is a disadvantage that the impregnation of the liquid into the organic fiber cord is deteriorated and the air permeability is increased.

Moreover, the single yarn fineness of the organic fiber cord is 10 dtex or more and 40 dtex or less.
By setting the single yarn fineness to 10 dtex or more, it is advantageous in reducing air permeability.
In addition, when the single yarn fineness is less than 10 dtex, it is disadvantageous for securing the strength, and when it exceeds 40 dtex, there is a disadvantage that the air permeability becomes high.
Further, the single yarn fineness is preferably 15 or more and 35 dtex or less in order to ensure the strength while reducing the air permeability.

The woven structure of the fabric constituting the chafer 28 is, for example, a plain weave or a twill weave.
By making the woven structure a twill weave, it is advantageous for improving the followability to the curved surface of the bead portion 13 at the time of molding the tire without lowering the wear resistance and improving the appearance.
In particular, PEN and PET have a higher elastic modulus than nylon that is usually used, so if the woven structure is a plain weave, there is a concern that the follow-up to the bead portion 13 may deteriorate. Needless to say, the improvement in wear resistance is advantageous in preventing failure during molding by ensuring the followability.

(Example)
The tires according to Examples 1, 2, and 3 according to the present embodiment and the tire according to the conventional example are respectively prepared, the following evaluation test is performed, and the measurement results are shown in FIG.
In the tires according to Examples 1, 2, 3, and the conventional example, the height a from the outermost rim diameter position in the tire radial direction was set to 1.8 times the rim flange height b.
(Conventional example)
A fabric made of an organic fiber cord made of nylon is used. The woven structure is plain weave. The loss coefficient tan δ at 20 ° C. of the coat rubber and the rim cushion rubber covering the organic fiber cord is 0.2. The sum of the cover factors CFv and CFh is 1700, the fineness of the organic fiber cord is 1400 dtex, the twist coefficient of the organic fiber cord is 930, and the single yarn fineness is 6.
(Examples 1-3)
A fabric made of an organic fiber cord made of PEN is used.
The loss factor tan δ at 20 ° C. of the coated rubber and rim cushion rubber covering the organic fiber cord, the sum of the cover factors CFv and CFh, the fineness of the organic fiber cord, the twist coefficient, and the single yarn fineness are changed as shown in FIG. It was.

(Road noise)
A test tire with a size of 215 / 55R17 was assembled to a 17 × 7J wheel, the internal pressure was adjusted to 230 kPa, and the vehicle was mounted on a FR-driven vehicle with a displacement of 2000 cc.
A test course having a rough road surface was run at 60 km / h, and the sound inside the vehicle was measured. The evaluation results were evaluated using reciprocal numbers and indicated by index values based on the conventional tire value (reciprocal number) as the reference (100). The larger this index is, the smaller the road noise is, and it is clear that the road noise is reduced in Examples 1, 2, and 3.
(Ride comfort)
A test tire with a tire size of 215 / 55R17 was assembled to a 17 × 7J wheel, the internal pressure was adjusted to 230 kPa, and the vehicle was mounted on a FR-driven vehicle with a displacement of 2000 cc.
Our test panel evaluated the actual vehicle ride performance feeling, and compared it with an index with the conventional product as 100. It is clear that the larger this index is, the better the ride performance feeling is, and the ride quality is improved by Examples 1, 2, and 3.

(Air permeability)
A 5 cm long trauma was made to reach the chafer position on the inner surface of the tire, and after adjusting to the JIS standard rim and standard air pressure, the air pressure was measured. The air leakage for 3 months was measured and indexed. It is clear that the larger the index, the lower the air permeability, and the air permeability higher than that of the conventional example is secured by Examples 1, 2, and 3.

  According to the present invention, since the organic fiber cord constituting the chafer has vibration absorption performance, transmission of vibration can be effectively suppressed between the tire and the rim, which is advantageous in improving quietness. In addition, it is possible to further improve the quietness of the tire by using it together with a tread pattern for improving the quietness of the tire and a device of a belt cover material.

It is meridian sectional drawing of a pneumatic tire. It is an expanded sectional view of a bead part. It is a figure which shows the measurement result of an evaluation test.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... Carcass ply, 13 ... Bead part, 14 ... Bead core, 28 ... Chafer, 30 ... Rim cushion rubber.

Claims (9)

A carcass ply is mounted on the bead core of the pair of left and right bead parts,
A chafer is provided that wraps around the portion of the carcass ply along the bead toe from the bead heel of the bead portion and can contact the rim.
The chafer is a pneumatic tire configured to include an organic fiber cord,
The organic fiber cord is a material having vibration absorption performance,
A pneumatic tire characterized by that. The material having vibration absorption performance is PEN (polyethylene naphthalate), PET (polyethylene terephthalate), POK (polyolefin ketone), or acrylic,
The pneumatic tire according to claim 1. The chafer is configured to include a coat rubber that covers the organic fiber cord,
The loss coefficient tan δ at 20 ° C. of the coated rubber is 0.25 or more and 0.40 or less.
The pneumatic tire according to claim 1 or 2, wherein A rim cushion rubber is arranged at a location where the bead heel contacts the rim at a location from the bead heel to the sidewall portion,
The loss coefficient tan δ at 20 ° C. of the rim cushion rubber is not less than 0.25 and not more than 0.40, and the height of the rim cushion rubber from the outermost rim diameter position in the tire radial direction of the tire surface is the rim flange. 1.0 to 2.0 times the height,
The pneumatic tire according to any one of claims 1 to 3, characterized in that: The chafer is constructed using a fabric composed of the organic fiber cord,
The warp angle of the woven fabric is 45 degrees or more and 75 degrees or less with respect to the tire circumferential direction.
The pneumatic tire according to any one of claims 1 to 4, characterized in that: The chafer is constructed using a fabric composed of the organic fiber cord,
The fineness of the organic fiber cord is 250 or more and 800 dtex or less, and the sum of the warp cover factor CFv calculated from the following formula (1) and the weft cover factor CFh calculated from the following formula (2) is 1000 or more and 3000 or less. is there,
The pneumatic tire according to any one of claims 1 to 5, characterized in that:
CFv = Nv · (Sv) ^1/2 (1)
CFh = Nh · (Sh) ^1/2 (2)
However, Nv: Warp density (1 / 5cm)
Nh: Weft density (1 / 5cm)
Sv: warp fineness (dtex)
Sh: Weft fineness (dtex) The fineness of the organic fiber cord is 250 or more and 800 dtex or less,
The twist coefficient of the organic fiber cord is 100 or more and 500 or less,
The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is any one of the above. The single yarn fineness of the organic fiber cord is 10 dtex or more,
The pneumatic tire according to any one of claims 1 to 7, characterized in that The chafer is constructed using a fabric composed of the organic fiber cord,
The woven structure of the woven fabric is a twill weave,
The pneumatic tire according to any one of claims 1 to 8, characterized in that

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