JP2010173573A - Pneumatic radial tire for passenger car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire for a passenger car for reducing a columnar resonance sound, without reducing its durability, in the pneumatic radial tire for the passenger car for constituting a carcass layer of a steel cord. <P>SOLUTION: This pneumatic radial tire for the passenger car is provided so that the carcass layer 4 is composed of the steel cord 8, and a belt layer 6 is arranged on the outer peripheral side of the carcass layer 4, and is characterized in that an inter-surface distance (d) between the carcass layer 4 and the belt layer 6 is set to 0.5 mm or more, and a sound absorbing material 10 is continuously or intermittently installed in the tire peripheral direction on a tire inner peripheral surface in a tire cavity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic radial tire for passenger cars, and more specifically, a passenger vehicle in which air column resonance noise is reduced without reducing the durability of a pneumatic radial tire for passenger cars in which a carcass layer is formed of a steel cord. The present invention relates to pneumatic radial tires.

  In recent years, pneumatic radial tires for high-performance passenger cars have increased tire rigidity by making the carcass layer of steel cords instead of organic fiber cords as a means of further improving steering stability at high speeds. Things have been done. However, when the carcass layer is made of steel cord, there is a problem that room noise due to air column resonance generated in the tire cavity becomes larger than when the carcass layer is made of organic fiber cord. As a means for reducing the air column resonance noise, it is known that it is effective to arrange a sound absorbing material made of a sponge material on the inner peripheral surface in the tire cavity (see, for example, Patent Document 1).

  However, since the tire in which the carcass layer is formed of a steel cord has high radial rigidity of the carcass layer, the shear strain between the carcass layer and the belt layer end portion is large, and the heat generation in this portion becomes very large. Therefore, when the sound absorbing material is disposed on the tire inner peripheral surface as described above, the heat dissipation generated by the sound absorbing material is hindered by the sound absorbing material, so that the rubber deteriorates and the tire durability decreases. There was a problem.

JP 2003-252003 A

  An object of the present invention is to provide a pneumatic radial tire for a passenger car in which the air column resonance noise is reduced without lowering the durability of the pneumatic radial tire for a passenger car in which a carcass layer is formed of a steel cord. There is.

  The pneumatic radial tire for passenger cars of the present invention that achieves the above object is the pneumatic radial tire for passenger cars, wherein the carcass layer is made of a steel cord, and a belt layer is provided on the outer peripheral side of the carcass layer. The distance between the surfaces of the cord is set to 0.5 mm or more, and a sound absorbing material is continuously or intermittently attached in the tire circumferential direction on the tire inner circumferential surface in the tire cavity.

  In the present invention, the distance between the cords of the carcass layer and the belt layer is more preferably 0.8 mm or more and 2.0 mm or less. The volume of the sound absorbing material is preferably 5% or more and 25% or less of the volume inside the tire cavity. More preferably, a rubber sheet layer is interposed between the carcass layer and the belt layer.

  As the sound absorbing material, polyurethane foam having open cells is preferably used, and the belt layer is preferably made of a steel cord.

  According to the present invention, since the surface-to-surface distance between the cords of the carcass layer made of steel cord and the belt layer is 0.5 mm or more, the shear strain generated between the carcass layer and the belt layer is alleviated to generate heat. In order to suppress and disperse, even when the sound absorbing material is attached to the inner peripheral surface of the tire, it is possible to suppress failure such as belt peeling at the end of the belt layer in the tire width direction and to prevent deterioration of tire durability. . In addition, the noise absorbing material is continuously or intermittently attached to the inner circumferential surface of the tire in the circumferential direction to reduce noise caused by air column resonance in the tire cavity and between the cords of the carcass layer and the belt layer. Since the distance between the surfaces of the belt is 0.5 mm or more, vibration transmission from the belt layer to the carcass layer is suppressed, and indoor noise can be further reduced in synergy with the effect of suppressing air column resonance by the sound absorbing material.

1 is a half cross-sectional view in the tire meridian direction showing an example of an embodiment of a pneumatic radial tire for passenger cars of the present invention. FIG. 1 is a partial cross-sectional view in the tire equator direction showing a part of a carcass layer and a belt layer in FIG. 1. FIG. 3 is a partial cross-sectional view corresponding to FIG. 2 in an example of another embodiment of the present invention.

  FIG. 1 is a half sectional view in the tire meridian direction showing an example of an embodiment of a pneumatic radial tire for passenger cars of the present invention.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, 3 is a bead portion, and 4 is a carcass layer. The carcass layer 4 has a carcass cord made of steel cord. The carcass layer 4 is mounted between a pair of left and right bead cores 5 embedded in the bead portion 3, and both end portions thereof are folded around the bead core 5 from the tire inner side to the outer side. Inside the tread portion 1, a belt layer 6 made of a pair of upper and lower steel cords is disposed over the circumference of the tire on the outer peripheral side of the carcass layer 4, and a rubber sheet layer 7 is interposed between the carcass layer 4 and the belt layer 6. Intervene. A sound absorbing material 10 made of a resin material containing open cells is attached to the tire inner peripheral surface of the tread portion 1 continuously or intermittently in the tire circumferential direction.

  In the tire of the present invention, since the carcass layer 4 is made of a steel cord, the side rigidity is higher than that of a tire made of an organic fiber cord, and the steering stability during high-speed running is significantly improved. The steel cord used for the carcass layer is not particularly limited as long as it is normally used for tire materials.

  Further, when the sound absorbing material 10 is continuously or intermittently disposed in the tire circumferential direction on the tire inner circumferential surface corresponding to the tread portion 1 in the tire cavity, in particular, when the carcass layer is made of a steel cord. It absorbs air column resonance sound that appears prominently in the interior, and can reduce room noise.

  In the tire configuration described above, between the carcass layer 4 made of steel cord and the belt layer 6, as shown in FIG. 2, a carcass cord 8 constituting the carcass layer 4 and a belt cord 9 constituting the belt layer 6. The inter-surface distance d between the cords is set to 0.5 mm or more and 2.5 mm or less. By maintaining the distance between the cords in this way, it is possible to relieve a large shear strain between the carcass layer and the belt layer generated due to the carcass layer 4 being a steel cord, and to suppress heat generation. . In order to suppress heat generation in this manner, rubber peeling at the end of the belt layer is suppressed so as not to reduce tire durability. Further, by setting the inter-surface distance d between the cords of the carcass layer 4 and the belt layer 6 to 0.5 mm or more, vibration transmission from the belt layer 6 to the carcass layer 4 is suppressed, and the sound absorbing effect by the sound absorbing material 10 is reduced. Synergistically, indoor noise can be further reduced.

  If the inter-surface distance d between the cords of the carcass layer 4 and the belt layer 6 is less than 0.5 mm, the shear strain between the carcass cord 8 and the belt cord 9 cannot be sufficiently relaxed, and the heat generation is large. Therefore, the tire durability cannot be sufficiently prevented from decreasing. Further, vibration transmission from the belt layer to the carcass layer cannot be reduced. On the other hand, if the distance d between the surfaces exceeds 2.5 mm, the tire weight increases due to an increase in the rubber amount. The inter-surface distance d between the cords is more preferably 0.8 to 2.0 mm.

  Even if the rubber sheet layer 7 is interposed between the carcass layer 4 and the belt layer 6 as shown in FIG. 2, or the rubber sheet layer is not used as shown in FIG. 3, the carcass layer 4 and the belt layer. The carcass layer 4 and the belt layer 6 may be directly laminated by adjusting the thickness of the covering rubber 6. However, the distance d between the surfaces of the cords between the carcass layer 4 and the belt layer 6 is easily adjusted by interposing a thin rubber sheet layer 7 therebetween as shown in FIG. be able to. Moreover, since it is not necessary to increase the amount of covering rubber for the carcass layer 4 and the belt layer 6 by using the rubber sheet layer 7, an increase in tire weight can be suppressed. The rubber composition constituting the rubber sheet layer 7 is not particularly limited, but it is preferable to use the same rubber composition as the covering rubber constituting the carcass layer or the belt layer.

In the present invention, the sound absorbing material attached to the inner circumferential surface of the tire corresponding to the tread portion extends in the tire circumferential direction, and may be attached so as to be continuous over the circumference of the tire or may be attached intermittently. . The volume of the sound absorbing material is preferably 5% or more and 25% or less, more preferably 15% to 25% of the volume inside the tire cavity. If the volume of the sound absorbing material is less than 5% of the volume in the cavity, the effect of reducing air column resonance is insufficient. If the volume of the sound absorbing material exceeds 25% of the volume in the cavity, the effect of reducing the air column resonance is saturated and the tire weight increases. In the present invention, the volume in the cavity of the pneumatic radial tire refers to the volume in the cavity when a tire without a sound absorbing material is assembled to the rim and filled with an internal pressure of 240 kPa. The measurement method follows the following method. First, a tire to which no sound absorbing material is attached is assembled to a rim by a predetermined method, and after being left at an internal pressure of 240 kPa for 24 hours or more, the internal pressure is adjusted again to 240 kPa. A weight of about 40 kg is attached to the rim of the rim-assembled tire, and the total weight (total weight of the rim-assembled tire and the weight) is measured in air at a room temperature of 25 ° C and in water at a water temperature of 25 ° C. Let W _A and W _A ′. In addition, the weight of the tire, rim, and weight in the air at room temperature of 25 ° C. is measured and set as W _T , W _R , and W _W , respectively. Similarly, the weights of tires, rims, and weights in water at a water temperature of 25 ° C. are measured and are set as W _T ′, W _R ′, and W _W ′. Thus, the respective volumes V _T , V _R , V _W and V _A of the tire, the rim, the weight, and the whole (total of the rim-assembled tire and the weight) are obtained by the following equations.
Vi = (Wi−Wi ′) / ρ

In the above formula, Vi is volume (m ³ ), Wi is weight in air (kg), Wi ′ is weight in water (kg), ρ is the density of water (1 × 10 ⁻³ kg / m ³ ), attached The letter i represents T (tire), R (rim), W (weight), and A (total of rim assembled tire and weight).

From the volume V _T, V _R, V _W and V _A of the tire, rim, weight and overall obtained by the above (a total of rim tire and weight), the tire cavity volume V is obtained by the following equation.
V = V _A − (V _T + V _R + V _W )

The material of the sound absorbing material used in the present invention is not particularly limited, and may be any porous material such as foamed resin, foamed rubber, non-woven fabric, and sponge, and those having open cells are particularly preferable. Examples of the foamed resin include a foamed urethane resin and a foamed polypropylene resin. Among foamed urethane resins, polyurethane foam is particularly preferable because it is difficult to compress and deform against the tire internal pressure and has excellent pressure resistance. The polyurethane foam preferably has a low density, and is preferably 0.01 to 0.1 g / cm ³ . When the density of the polyurethane foam is less than 0.01 g / cm ³ , the mechanical strength is insufficient, and it is difficult to fix the polyurethane foam to the tire rim against centrifugal force and repeated deformation. On the other hand, when the density of the polyurethane foam exceeds 0.1 g / cm ³ , the effect of reducing the air column resonance noise becomes insufficient and the tire weight increases.

  The rubber composition constituting the covering rubber of the carcass layer and the belt layer and the rubber composition of the rubber sheet layer may be those that are usually used as a rubber composition for a pneumatic radial tire. Moreover, the belt cord which comprises a belt layer should just be a belt cord which can be used for a pneumatic radial tire for passenger cars. A steel cord is preferably used as the belt cord.

  Hereinafter, the present invention will be described with reference to examples, but the scope of the present invention is not limited thereby.

  The tire size 215 / 60R16, the tire structure shown in FIG. 1, the common condition is that the steel cord is used as the carcass cord and the steel cord is used as the belt cord, and the inter-surface distance d between the carcass cord and the belt cord is d. (In the table, expressed as “distance between cords d”), presence / absence of sound absorbing material, volume fraction of sound absorbing material with respect to volume of tire cavity when sound absorbing material is arranged are varied as shown in Tables 1 and 2. Fourteen pneumatic radial tires for passenger cars (Examples 1 to 10, Comparative Examples 1 to 3, and a conventional example) were manufactured. The sound absorbing material was made of polyurethane foam having open cells and was intermittently attached to the tire inner peripheral surface in the circumferential direction.

  The resulting 14 types of pneumatic radial tires for passenger cars were assembled on a rim (size 16 × 6.5JJ), and vehicle interior noise, vehicle interior noise feeling and durability were evaluated by the following methods.

Vehicle interior noise Rim-assembled pneumatic radial tires are adjusted to 220 kPa, and installed in a domestic 2.4 liter vehicle, the interior noise characteristics of the vehicle when driving on a test course at 60 km / h were installed at the driver's seat window side position. Sound was collected with a microphone, and a frequency spectrum was obtained to obtain a peak sound pressure (dB) near 250 Hz. The measurement results are shown in Tables 1 and 2 as “vehicle interior noise” as the difference from the peak sound pressure of the conventional pneumatic radial tire. The lower the “vehicle interior noise” value, the better the low noise performance.

Vehicle interior noise feeling Adjusting the radial tires with rims to 220 kPa, mounting them on a domestic 2.4 liter FR vehicle, the vehicle interior noise when five trained drivers run the test course. The feeling was evaluated. The determination method is 3 (standard) for the conventional pneumatic radial tire, 5 (excellent), 4 (excellent), 3.5 (slightly superior), 3 (equal to the standard), 2.5 (slightly inferior) Evaluation was based on criteria of 2 (inferior) and 1 (largely inferior). The obtained results are shown in Tables 1 and 2 as the average score of three people excluding the highest point and the lowest point. A rating of 2.5 (slightly inferior) is the practical lower limit level.

Durability Pneumatic radial tires assembled with rims were sealed with oxygen at 280 kPa and kept in a chamber at room temperature of 70 ° C. for 2 weeks. Thereafter, oxygen inside the tire was released, and air was filled at 170 kPa. The test tire thus pretreated was subjected to a steel drum testing machine (diameter 1707 mm) having a smooth drum surface in accordance with JIS D4230, the ambient temperature was controlled to 38 ± 3 ° C., the running speed was 50 km / h, The slip angle and the load were changed with a rectangular wave of 0.083 Hz for 100 hours under a fluctuation condition of 0 ° ± 3 ° and the load was 70% ± 40% of the maximum load specified by JATMA. . After running, the test tire was incised, and the presence or absence of separation in the width direction at the end of the belt layer in the tire width direction (peeling portion having a length of 5 mm or more) was confirmed. The obtained results are shown in Tables 1 and 2 as “presence / absence of belt peeling”. If there is no belt peeling, it means excellent durability.

1 tread portion 3 bead portion 4 carcass layer 6 belt layer 7 rubber sheet layer 8 carcass cord 9 belt cord 10 sound absorbing material d distance between surfaces

Claims (6)

In a pneumatic radial tire for a passenger car in which the carcass layer is made of a steel cord and a belt layer is provided on the outer peripheral side of the carcass layer,
Air for passenger cars in which the distance between the surfaces of the cords of the carcass layer and the belt layer is 0.5 mm or more, and the sound absorbing material is continuously or intermittently attached to the tire inner circumferential surface in the tire cavity in the tire circumferential direction. Entering radial tire.   The pneumatic radial tire for passenger cars according to claim 1, wherein a distance between surfaces of the cords of the carcass layer and the belt layer is 0.8 mm or more and 2.0 mm or less.   The pneumatic radial tire for a passenger car according to claim 1 or 2, wherein a volume of the sound absorbing material is 5% or more and 25% or less of a tire cavity internal volume.   The pneumatic radial tire for passenger cars according to claim 1, wherein a rubber sheet layer is interposed between the carcass layer and the belt layer.   The pneumatic radial tire for a passenger car according to any one of claims 1 to 4, wherein the sound absorbing material is made of polyurethane foam having open cells.   The pneumatic radial tire for a passenger car according to any one of claims 1 to 5, wherein the belt layer is made of a steel cord.

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