JP2014213837A - Pneumatic radial tire and assembly of the same and rim - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire which can improve ride comport of a vehicle while reducing road noise.SOLUTION: The pneumatic radial tire includes: a pair of bead parts 1; a pair of side wall parts 2; a tread part 3 connecting to both of the side wall parts; one or more radial carcasses 4 extended in a toroidal shape between the pair of bead parts 1; a belt 5 formed of at least two angled steel belt layers 5a arranged on an outer side of a crown part of the carcass 4 in a tire radial direction; and a belt reinforcing layer 6 which is arranged on an outer side of the belt 5 in the tire radial direction and is formed by spirally winding an organic fiber cord in a tire circumferential direction. A sound absorption member 9 is arranged on a tire inner cavity side. When the tire is incorporated with a rim and an inner pressure is 250kPa, a cross sectional width SW and an outer diameter OD of the tire have a specific relationship.

Description

  The present invention relates to a pneumatic radial tire and an assembly thereof with a rim.

  In recent years, under the social demand for energy saving and resource saving, automobiles and the like are becoming more demanding of lower fuel consumption, and tires with low rolling resistance are required.

  As one example focusing on the reduction of the rolling resistance, Patent Document 1 discloses that a widened tire, which has been used so far, is narrowed under specific conditions to increase the tire weight and the air resistance. A pneumatic radial tire for passenger cars is disclosed that can reduce rolling resistance by reducing the contact area with the road surface while solving such problems.

International Publication No. 2012/176476

  However, since the pneumatic radial tire has a small contact area with the road surface, the contact pressure tends to increase due to its structure. For this reason, there is a problem in that the vibration frequency increases when it is in contact with the road surface unevenness, resulting in poor ride comfort. Furthermore, there is also a problem that the increase in the frequency causes the gas filled in the tire lumen to vibrate and so-called road noise can occur. Since road noise has a remarkably high peak value as compared with noise in other frequency bands, if it is transmitted to the interior of the vehicle, it becomes annoying noise for passengers.

  Accordingly, an object of the present invention is to provide a pneumatic radial tire that can improve the riding comfort of a vehicle while reducing road noise in view of the above-described problems of the prior art. Another object of the present invention is to provide an assembly of such a pneumatic radial tire and a rim.

  As a result of intensive studies to achieve the above object, the present inventors have reduced the road noise and reduced the ride comfort by arranging the sound absorbing member on the tire lumen side while narrowing under specific conditions. The present inventors have found that a tire having excellent properties can be obtained, and have completed the present invention.

That is, the pneumatic radial tire of the present invention is
One or more radial carcasses having a pair of bead portions and a pair of sidewall portions, and a tread portion connected to both sidewall portions, and extending in a toroid shape between the pair of bead portions; A belt composed of at least two angled steel belt layers disposed on the outer side in the tire radial direction of the crown portion; a belt reinforcing layer disposed adjacent to the belt and spirally wound with an organic fiber cord in the tire circumferential direction; With
Furthermore, a sound absorbing member is provided on the tire lumen side,
When the tire is incorporated into the rim and the internal pressure is 250 kPa,
When the cross-sectional width SW of the tire is less than 165 (mm), the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD is 0.26 or less,
When the cross-sectional width SW of the tire is 165 (mm) or more, the cross-sectional width SW and the outer diameter OD of the tire are expressed by the relational expression (I):
OD (mm) ≧ 2.135 × SW + 282.3 (I)
It is characterized by satisfying.
In the present invention, the “rim” means a width corresponding to the bead width of the tire.

  In the pneumatic radial tire of the present invention, the sound absorbing member is preferably a porous sound absorber. The porous sound absorber is made of foamed rubber or synthetic resin and is a material having open cells or closed cells, or entangled with animal fibers, plant fibers and / or synthetic fibers. A fiber assembly material is preferred.

  In the pneumatic radial tire of the present invention, it is preferable that an inner liner is further provided on the tire inner surface side of the carcass, and the sound absorbing member is provided on the inner surface of the inner liner.

  In the pneumatic radial tire of the present invention, the sound absorbing member is preferably provided on the entire inner surface of the tire. On the other hand, it is also preferable to provide the sound absorbing member on a part of the tire inner surface.

  In the pneumatic radial tire of the present invention, it is preferable that the sound absorbing member is provided on the inner surface of the inner liner at least in the center in the tire width direction.

  In the pneumatic radial tire of the present invention, the width of the sound absorbing member in the tire width direction is preferably 10% or more of the width of the belt.

  In the pneumatic radial tire of the present invention, it is preferable that the sound absorbing member has a thickness of 5 mm to 50 mm.

  The tire / rim assembly of the present invention is a combination of the pneumatic radial tire and the rim of the present invention.

  According to the present invention, it is possible to provide a pneumatic radial tire that can improve the riding comfort of a vehicle while reducing road noise. Moreover, the assembly of such a pneumatic radial tire and a rim can be provided.

1 is a cross-sectional view in the width direction of one embodiment of a pneumatic radial tire of the present invention.

Hereinafter, the pneumatic radial tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of one embodiment of the pneumatic radial tire of the present invention. The pneumatic radial tire shown in FIG. 1 has a pair of bead portions 1 and a pair of sidewall portions 2 and a tread portion 3 connected to both sidewall portions, and extends in a toroidal shape between the pair of bead portions 1. A radial carcass 4 that reinforces each of these parts 1, 2, 3, a belt 5 comprising two angled steel belt layers 5 a disposed on the outer side in the tire radial direction of the crown part of the carcass 4, and the belt 5 and a belt reinforcing layer 6 which is arranged adjacent to 5 and spirally wound in the tire circumferential direction.

  In the pneumatic radial tire of FIG. 1, the belt 5 is composed of two angled steel belt layers 5a. However, in the pneumatic radial tire of the present invention, at least two steel belt layers may be provided. Well, therefore you may have more than two. Here, the steel belt layer is composed of a rubberized layer of a steel cord extending at an angle with respect to the tire circumferential direction, and the belt includes at least two such steel belt layers, each steel belt layer being The steel cords to be formed are laminated so as to alternately intersect at a specific angle with respect to the tire circumferential direction. In the preferred example of the pneumatic radial tire of the present invention, the steel cords constituting each steel belt layer are laminated so as to intersect within a range of 10 to 75 ° with respect to the tire circumferential direction.

  Here, the steel cord is formed by twisting a plurality of steel filaments, and in the present invention, a single-twisted steel cord consisting of a single twist, and two to three layers around the center sequentially. It is preferable to use a twisted steel cord or a double twisted steel cord in which a plurality of twisted cords are further twisted. Moreover, it is preferable that the diameter of the said steel filament is 0.09-0.40 mm.

  The number of driven steel cords is preferably 15 to 70 per 50 mm, the twist pitch of the steel cords is preferably 4 to 20 mm, and the carbon amount of the steel cords is 0.7% by mass. The above is preferable.

  The pneumatic radial tire in FIG. 1 includes a belt reinforcing layer 6 on the outer side in the tire radial direction of the belt 5, and the belt reinforcing layer 6 is formed by spirally winding an organic fiber cord in the tire circumferential direction. The organic fiber cord provided for the belt reinforcing layer may be a single twisted cord, a double twisted cord, or three or more multiple twisted cords. The organic fiber cord to be used for the belt reinforcing layer may be one in which filaments of one type of organic fiber are twisted or one in which filaments of two or more types of organic fibers are twisted (so-called composite cord). Furthermore, it is preferable that the number of organic fiber cords used for the belt reinforcing layer is 30 to 80 per 50 mm. In addition, regarding the driving of the organic fiber cords, the cords may be arranged evenly over the entire belt reinforcing layer or at intervals under the tread grooves according to the shape of the tread.

The total fineness of one organic fiber cord provided for the belt reinforcing layer is preferably 470 to 5000 dtex. The organic fiber cord provided for the belt reinforcing layer has the following formula (II):
N ₁ = n ₁ × (0.125 × D ₁ / ρ) ^1/2 × 10 ⁻³ (II)
[Where n ₁ is the number of lower twists (times / 10 cm), D ₁ is the total fineness of the cord, and ρ is the specific gravity (g / cm ³ ) of the cord] ₁ is preferably 0.05 to 0.5, and the following formula (III):
N ₂ = n ₂ × (0.125 × D ₂ / ρ) ^1/2 × 10 ⁻³ (III)
[Where n ₂ is the number of upper twists (times / 10 cm), D ₂ is the total fineness of the cord, and ρ is the specific gravity (g / cm ³ ) of the cord] ₂ is preferably 0.05 to 0.5.

  The belt reinforcing layer in the pneumatic radial tire of the present invention is disposed adjacent to the belt by spirally winding the organic fiber cord described above. In one embodiment of the present invention, as shown in FIG. 1, the belt reinforcing layer 6 can be disposed so as to cover the center part in the tire width direction of the at least two angled steel belt layers 5a. (Hereinafter, the belt reinforcing layer having the above configuration is referred to as “belt reinforcing layer A”), and two or more belt reinforcing layers A may be provided. Furthermore, in another embodiment of the present invention, the belt reinforcing layer can be disposed in a pair so as to cover both ends of the at least two angled steel belt layers in the tire width direction (hereinafter referred to as the pair). The belt reinforcing layer having the above-described configuration is referred to as “belt reinforcing layer B”), and the belt reinforcing layers B may be provided in two or more pairs. In the pneumatic radial tire of the present invention, the belt reinforcing layer A and the belt reinforcing layer B can be provided side by side. In this case, the belt reinforcing layer A is made of a continuous or intermittent organic fiber cord. In a spiral winding structure, disposed from the center in the tire width direction to the vicinity of the belt reinforcing layer B; disposed until it overlaps the end of the belt reinforcing layer B; or disposed from the belt reinforcing layer B to the outside in the tire width direction. can do. Furthermore, in another embodiment of the present invention, the belt reinforcing layer may be disposed on the inner side in the tire radial direction of the belt.

  Further, in the pneumatic radial tire of the present invention, when two or more belt reinforcing layers are provided, the width of each belt reinforcing layer in the tire width direction is 10% or more of the width of the belt. It is preferable. Further, in the pneumatic radial tire of the present invention, when the belt reinforcing layers are arranged in a pair, the sum of the widths in the tire width direction of the respective belt reinforcing layers constituting the pair is the width of the belt. It is preferable that it is 10% or more.

  The organic fiber cord used for the belt reinforcing layer A is preferably made of aliphatic polyamide fiber or polyester fiber. On the other hand, the organic fiber cord provided for the belt reinforcing layer B preferably contains at least 20% by mass of aliphatic polyamide fiber or polyester fiber.

  Further, in the pneumatic radial tire of FIG. 1, the radial carcass 4 is composed of a single carcass ply formed by coating a plurality of cords arranged in parallel with a coating rubber. In the pneumatic radial tire of the present invention, The number of plies of the carcass 4 is not limited to this, and may be two or more. In the pneumatic radial tire of FIG. 1, the carcass 4 includes a main body portion extending in a toroid shape between bead cores 7 embedded in the pair of bead portions 1, and a bead core 7 around the bead core 7 from the inner side in the tire width direction to the outer side. However, the structure of the carcass 4 in the pneumatic radial tire of the present invention is not limited to this, and the bead core 7 is surrounded from the inner side in the tire width direction to the outer side. Wrapped up toward the bead core 7, surrounding the entire circumference of the bead core 7, terminating at approximately the outer side of the bead core 7 in the tire width direction without being rolled up, and having a down ply structure extending to the inner side of the tire width direction immediately below the bead core 7 A structure having a structure sandwiched between two or more pairs of beads may be used.

  The radial carcass is usually composed of an organic fiber cord. The organic fiber cord used for the radial carcass can be a single twisted cord, a double twisted cord, or three or more multiple twisted cords. The organic fiber cord used for the radial carcass may be one obtained by twisting filaments of one kind of organic fiber, or may be one obtained by twisting filaments of two or more kinds of organic fibers. Furthermore, it is preferable that the number of driven organic fiber cords provided to the radial carcass is 40 to 70 per 50 mm.

The total fineness of one organic fiber cord used for the radial carcass is preferably 1000 to 7000 dtex. The organic fiber cord to be subjected to the belt reinforcing layer is preferably lower twist factor _{N 1} defined by the formula (II) is 0.05 to 0.8, defined by the following formula (III) upper twist factor _{N 2} is preferably 0.3 to 0.8.

  The organic fiber cord used for the radial carcass is preferably made of polyamide fiber, polyester fiber, or rayon fiber.

  The pneumatic radial tire of the present invention further includes a sound absorbing member 9 on the tire lumen side. Thereby, the vibration energy of the filling gas generated on the tire lumen side is converted into the internal vibration energy of the sound absorbing member 9 and is consumed as heat energy, thereby reducing road noise. Here, it is preferable that the sound absorbing member is a porous sound absorber, and a higher road noise reduction effect can be obtained by providing the porous sound absorber on the tire lumen side.

  Further, when the sound absorbing member is a porous sound absorbing body, the porous sound absorbing body is made of foamed rubber or synthetic resin and is a material having open cells or closed cells, or animal fibers, plant fibers. And / or a fiber assembly material in which synthetic fibers are entangled and integrated. A nonwoven fabric is mentioned as said fiber assembly material. By using such a material, road noise can be further reduced and riding comfort can be improved.

により定義したとき、該多孔度Φは０．９５以上であり、該繊維間の平均距離ｄが０．５０δ〜４．００δの範囲内にあることが好ましい。 The nonwoven fabric has a density of gas filled in the tire as ρ _a (kg / m ³ ), and a primary natural angular frequency of cavity resonance of the filled gas in the tire lumen when the tire / rim assembly is unloaded is ω. (Rad / s), the viscosity coefficient of the filling gas is η (Pa · s), the density of the nonwoven fabric is ρ _b (kg / m ³ ), the density of the fiber is ρ _f (kg / m ³ ), The average cross-sectional radius is r (μm), the skin thickness δ (μm) of the filling gas around the fiber, the average distance d (μm) between the fibers, and the porosity Φ of the nonwoven fabric are the following formulas (IV) to (VI ):

The porosity Φ is preferably 0.95 or more, and the average distance d between the fibers is preferably in the range of 0.50δ to 4.00δ.

  In a preferred example of the pneumatic radial tire of the present invention, as in the pneumatic radial tire of FIG. 1, an inner liner 8 is further provided on the tire inner surface side of the carcass 4, and the sound absorbing member is formed on the inner surface of the inner liner 8. With By providing the sound absorbing member on the inner surface of the inner liner, the possibility of peeling of the sound absorbing member due to the centrifugal force can be reduced.

  In the pneumatic radial tire of the present invention, it is preferable to provide the sound absorbing member on the entire inner surface of the tire from the viewpoint of further reducing road noise. On the other hand, in the pneumatic radial tire of the present invention, it is also preferable to include the sound absorbing member in a part of the tire inner surface from the viewpoint of suppressing deterioration of fuel consumption due to an increase in tire weight.

  In the pneumatic radial tire of the present invention, it is preferable that the sound absorbing member is provided on the inner surface of the inner liner at least in the center in the tire width direction. As a result, the center portion in the tire width direction protrudes due to the centrifugal force at the time of traveling, and the unevenness of the ground contact shape is corrected, so that riding comfort can be improved.

  In the pneumatic radial tire of the present invention, it is preferable that the width of the sound absorbing member in the tire width direction is 10% or more of the width of the belt. When the width of the sound absorbing member in the tire width direction satisfies the above requirements, sufficient reduction in road noise and improvement in ride comfort of the vehicle can be achieved.

  In the pneumatic radial tire of the present invention, it is preferable that the sound absorbing member has a thickness of 5 mm to 50 mm. When the thickness of the sound absorbing member is 5 mm or more, road noise can be sufficiently reduced. On the other hand, when the thickness of the sound absorbing member is 50 mm or less, peeling of the sound absorbing member is avoided. Can do.

Furthermore, the pneumatic radial tire of the present invention is
When the tire is incorporated into the rim and the internal pressure is 250 kPa or more,
When the cross-sectional width SW of the tire is less than 165 (mm), the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD is 0.26 or less,
When the cross-sectional width SW of the tire is 165 (mm) or more, the cross-sectional width SW and the outer diameter OD of the tire need to satisfy the relational expression (V).
When the tire cross-sectional width SW and the outer diameter OD satisfy the above relationship, both the tire rolling resistance and the tire weight can be reduced. However, the present inventors satisfy these relationships. Furthermore, it has been found that by providing a sound absorbing member on the tire lumen side, a tire with reduced road noise and improved ride comfort can be obtained by these synergistic effects. Such a synergistic effect is that the sound absorption is improved with respect to the specific vibration generated by the high internal pressure and narrowing of the tire, road noise can be more effectively suppressed than the conventional tire, and the above formula should be satisfied. This is considered to be due to the improvement of the ground contact shape by increasing the diameter of the tire.

The pneumatic radial tire of the present invention further reduces road noise and further increases ride comfort when the cross-sectional width SW is less than 165 (mm) and when the cross-sectional width SW is 165 (mm) or more. In order to achieve both improvement and SW, the outer diameter OD is expressed by the relational expression (VII);
OD ≧ −0.0187 × SW ² + 9.15 × SW-380 (VII)
It is preferable to satisfy. The pneumatic radial tire of the present invention preferably satisfies SW / OD ≦ 0.26, and further satisfies SW / OD ≦ 0.24 in order to further reduce road noise and further improve riding comfort. It is more preferable to satisfy.

  The pneumatic radial tire of the present invention includes a radial carcass, an angled steel belt layer, and a belt reinforcing layer as described above, and has a configuration in which the cross-sectional width SW and the outer diameter OD satisfy the above relationship. There is no particular limitation, and it can be produced by a usual method. As the gas filled in the pneumatic radial tire, an inert gas such as nitrogen, argon, helium, or the like can be used in addition to air having a normal or oxygen partial pressure adjusted.

The tire / rim assembly of the present invention is a combination of the pneumatic radial tire and the rim of the present invention. Such an assembly has reduced road noise and improved ride comfort.
The tire / rim assembly of the present invention is not particularly limited, and can be assembled by a normal method.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

The sound absorbing member is composed of a nonwoven fabric in which a plurality of polyester fibers are entangled and integrated, and the porosity Φ represented by the above formula (VI) is 0.97, and the interfiber space represented by the above formula (V) A porous sound absorber having an average distance d of 0.50δ to 4.00δ was used. The thickness of the sound absorbing member was set as shown in Table 1, and affixed to the tire cavity to produce a radial tire (size 165 / 60R20, cross-sectional width SW = 165 mm, outer diameter OD = 706 mm). And about the obtained prototype tire, the road noise property and riding comfort were evaluated with the following method.
The prototype tire includes a radial carcass, a belt composed of two angled steel belt layers (60 °), a belt reinforcing layer, and an inner liner. Further, the width of the sound absorbing member in the tire width direction was set to 50% of the width of the belt, and the center of the sound absorbing member in the tire width direction was matched with the center portion in the tire width direction. The results are shown in Table 1.

<Road noise>
The prototype tire was filled with gas to an internal pressure of 300 KPa and mounted on an actual vehicle. Then, the vehicle traveled on a rough road at a speed of 60 km / h, and the in-vehicle sound (decibel) was measured. The measured value of the in-vehicle sound in the actual vehicle equipped with the tire of Comparative Example 1 was taken as 100, and each index was displayed. It shows that road noise property is so favorable that this index value is small.

<Ride comfort>
In the same manner as described above, the vehicle was run on a rough road at a speed of 60 km / h, and the driver's sensitivity was evaluated for ride comfort. The highest score was 10 and the evaluation was performed in 10 stages. The larger this value, the better the actual vehicle performance.

  According to the results in Table 1, it can be seen that the pneumatic radial tire satisfying the requirements of the present invention has reduced road noise and improved riding comfort.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Radial carcass 5 Belt 5a Angled steel belt layer 6 Belt reinforcement layer 7 Bead core 8 Inner liner 9 Sound absorbing member

Claims (11)

One or more carcass having a pair of bead portions and a pair of sidewall portions, and a tread portion connected to both sidewall portions, and extending in a toroidal shape between the pair of bead portions, and a crown of the carcass A belt composed of at least two angled steel belt layers disposed on the outer side of the tire in the radial direction of the tire, and a belt reinforcing layer disposed adjacent to the belt and spirally wound with an organic fiber cord in the tire circumferential direction. A pneumatic radial tire,
Furthermore, a sound absorbing member is provided on the tire lumen side,
When the tire is incorporated into the rim and the internal pressure is 250 kPa,
When the cross-sectional width SW of the tire is less than 165 (mm), the ratio SW / OD of the cross-sectional width SW of the tire to the outer diameter OD is 0.26 or less,
When the cross-sectional width SW of the tire is 165 (mm) or more, the cross-sectional width SW and the outer diameter OD of the tire are expressed by the relational expression (I):
OD (mm) ≧ 2.135 × SW + 282.3 (I)
A pneumatic radial tire characterized by satisfying   The pneumatic radial tire according to claim 1, wherein the sound absorbing member is a porous sound absorber.   The pneumatic radial tire according to claim 2, wherein the porous sound absorber is a material made of foamed rubber or synthetic resin and having open cells or closed cells.   The pneumatic radial tire according to claim 2, wherein the porous sound absorber is a fiber assembly material in which animal fibers, plant fibers, and / or synthetic fibers are entangled and integrated.   The pneumatic radial tire according to any one of claims 1 to 4, further comprising an inner liner on the tire inner surface side of the carcass, and further comprising the sound absorbing member on an inner surface of the inner liner.   The pneumatic radial tire according to any one of claims 1 to 5, wherein the sound absorbing member is provided on the entire inner surface of the tire.   The pneumatic radial tire according to any one of claims 1 to 5, wherein the sound absorbing member is provided on a part of an inner surface of the tire.   The pneumatic radial tire according to claim 6 or 7, wherein the sound absorbing member is provided on an inner surface of the inner liner at least in a center portion in a tire width direction.   The pneumatic radial tire according to any one of claims 1 to 8, wherein a width of the sound absorbing member in a tire width direction is 10% or more of a width of the belt.   The pneumatic radial tire according to any one of claims 1 to 9, wherein the sound absorbing member has a thickness of 5 mm to 50 mm.   The pneumatic radial tire and rim assembly according to any one of claims 1 to 10.

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