JP2768464B2 - Pneumatic radial tires with improved ride comfort - Google Patents

Description

The present invention relates to a pneumatic radial tire having improved riding comfort without impairing steering stability, and is particularly used for a passenger car. (Prior Art) A pair of sidewall portions and a tread portion extending between both sidewall portions are connected in a toroidal manner, and each of these portions is formed from at least one ply of a layer arranged in a direction substantially orthogonal to the equatorial plane of the tire. Carcass,
A non-extensible belt layer is arranged between the carcass and the tread portion, and the tread portion is composed of a plurality of layers of an outer rubber layer located on the outer side in the radial direction of the tire and an inner rubber layer located on the inner side. Pneumatic radial tires are disclosed in
It is known in Japanese Patent Application Laid-Open No. 124411 (conventional example 1) and Japanese Patent Application Laid-Open No. 61-295103 (conventional example 2). (Problems to be Solved by the Invention) By the way, in the conventional example 1, although the dynamic elastic modulus of the tread surface layer (outer rubber layer) is set to 115 kg · f / cm ² or less, actually, As disclosed in that publication, 85 kg
an f / cm ^2, which in the case the vehicle goes over irregularities such as joints or manhole of a road, the contact of the tread surface layer to be grounded directly to the road surface too hard impact force becomes large, ride comfort difference It was not much improved. Also, in the conventional example 2, the dynamic elastic modulus of the tread portion outer rubber layer is 70 to 150 kg · f / cm ^2, and although the contact of the tread portion surface layer is softer than that of the conventional example 1, it is still the same. The hit was too hard, the impact force was large, and the riding comfort was not much improved. The present invention uses a rubber capable of softly hitting a road surface and suppressing an impact input as an outer rubber layer on a side directly contacting a road surface, and further using a rubber with a large damping property for an inner rubber layer, so that a vehicle can be used. When encountering irregularities such as road joints and manholes, the impact force is attenuated by the inner rubber layer to improve ride comfort despite suppressing the impact force,
An object of the present invention is to provide an inner filler in a side wall portion to provide its rigidity and secure steering stability. (Means for Solving the Problems) According to the present invention, a pair of sidewall portions and a tread portion extending between both sidewall portions are connected in a toroidal manner.
Each of these parts is reinforced with a carcass composed of at least one ply of a layer arranged in a direction substantially orthogonal to the equatorial plane of the tire, a non-extensible belt layer is arranged between the carcass and the tread part, and the tread part is In order to achieve the above-mentioned object, in a pneumatic radial tire composed of a plurality of layers of an outer rubber layer located on the outer side in the radial direction of the tire and an inner rubber layer located on the inner side, the following technical We took steps. That is, the power elastic modulus E ′ of the outer rubber layer 6 is E ′ ≦ E ′.
Are as 50kg · f / cm ^2, the inner rubber layer 7 loss tangent (tan [delta) is are the tan [delta ≧ 0.4, be provided in the inner side of the bead filler provided with the bead portion is stretched toward the shoulder portion near Inside filler is inserted into the sidewall part, and the filler is 8% at 200% M.
It is characterized by having rubber properties of 0 kg · f / cm ² or more. Furthermore, the present invention provides, in addition to the above-described configuration,
5,5A is composed of a plurality of layers, and a dynamic elastic modulus E 'is provided between the layers.
Is E '≦ 40 kg · f / cm ² and the loss tangent tanδ is tanδ
Soft and low damping cushion rubber layer 12 with ≦ 0.2
Is characterized by being interposed. (Operation) When a vehicle crosses a road joint or a manhole, a large impact force and deformation are applied to the tread portion 3 of the tire 1. In this case, the outer rubber layer 6 which is directly in contact with the road surface has a dynamic elastic modulus E 'of E'≤50 kg · f / cm ² and has a soft hit, so that a large impact input is softened. The inner rubber layer 7 has a loss tangent tanδ of tanδ ≧ 0.4.
Therefore, the impact input is made soft by the outer rubber layer 6 and the impact force is attenuated by the inner rubber layer 7. An inside filler 10 is inserted into the sidewall portion 2 from the bead portion to the vicinity of the shoulder portion.
Has a rubber property of 80 kg · f / cm ² or more at 200% M, so that the rigidity of the side wall portion 2 is improved and the outer rubber layer 6
Prevents the steering stability from deteriorating even with a soft touch. Further, in the present invention, between the belt layers 5, 5A made a plurality of layers,
When the dynamic elastic modulus E 'is E'≤40 kg · f / cm ² and the loss tangent tan
When δ is tan δ ≦ 0.2 and the cushion rubber 12 which is soft and has low damping property is interposed, the impact force is attenuated by the inner rubber layer 7 when riding over road unevenness, and the belt layer 5
It can absorb the large shear force generated at 5A and reduce the vibration transmission to the rim. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, reference numeral 1 denotes a pneumatic radial tire according to the present invention, which shows the right half from the equator plane OO, but the left half is symmetric with the right half. The tire 1 according to the present embodiment includes a pair of sidewall portions 2.
And a carcass 4 composed of at least one ply (two ply in the figure) of a layer in which a tread portion 3 extending between both sidewall portions is connected in a toroidal manner, and these portions are arranged in a direction substantially orthogonal to the equatorial plane of the tire. Reinforced. Inextensible belt layer 5,5A between carcass 4 and tread 3
In this example, the tread portion 3 is arranged as a two-layer steel belt, and the tread portion 3 is made up of a plurality of layers of an outer rubber layer 6 located outside in the radial direction of the tire and an inner rubber layer 7 located inside. It is configured. In FIG. 1, reference numeral 8 denotes a bead bundle, and 9 denotes a bead filler. The outer rubber layer 6 directly contacts the road surface. In order to soften the contact at the time of contact with the ground, the dynamic elastic modulus E ′ is set to E ′ ≦ 50 kg · f / cm ² , that is, 30 to 50k
g · f / cm ² . E 'is 35 to 45 kg · f / cm ²
It is desirable that Here, E ′ ≦ 50 kg · f / cm ² is defined as E ′> 50 kg · f
This is because, when it is / cm ² , when the tread portion 3 of the tire 1 encounters unevenness on the road surface, the tread portion is too hard and the impact force becomes large. Since the inner rubber layer 7 has a soft touch on the outer rubber layer 6, it is necessary to attenuate the vibration. For this reason, the loss tangent, that is, tan δ, is 0.4 to 0.7, preferably 0.60 to 0.7.
It is set to 0. Here, tan δ ≧ 0.4 is set because tan δ <0.4 is inconvenient for attenuating vibration. Reference numeral 10 denotes an inside filler, which extends from the bead portion to the vicinity of the shoulder portion and is inserted into the sidewall portion 2 inside the bead filler 9.
Has a rubber property of 80 kg · f / cm ² or more at 200% M (modulus), has a stretch length of about 2/3 of the tire height H, and has a thickness of 1.5 mm or less. . That is, since the rubber properties of the outer rubber layer 6 of the tread portion 3 are soft, there is a possibility that steering stability may be impaired.
The rigidity of the vehicle has been increased to prevent a decrease in steering stability. Referring to FIG. 2, the vibration evaluation, that is, the result of the envelope characteristic is shown by the impact force PP and the damping rate λ at the time of the overshoot of the protrusion, and as is clear from this, the protrusions (road joints, manholes, etc.) are also apparent. ), Even if a large impact force and deformation are applied to the tread portion 3 of the tire, the outer rubber layer 6 softens the contact with the road surface, and the inner rubber layer 7 attenuates the impact force to improve ride comfort. It can be understood that it has been improved. The experimental tire shown in FIG. 2 is as follows. Tire Type 165SR13 Tire Internal Pressure 1.8kg ・ f / cm ² Load 310kg Speed 40km / hr Referring to FIG. 3, a second embodiment of the present invention is shown, which is common with the first embodiment shown in FIG. The parts to be described are denoted by common symbols, and the differences will be described in detail below. Reference numeral 11 denotes an organic fiber layer (under ply), which is a rubberized sheet of nylon or polyester cord. As shown in FIGS. 4 and 5, when the cord angle of the belt layers 5, 5A is α ゜, Underply cord cord angle β
゜ is β ゜ = α ゜ ± 4 or β ゜ = −α ゜ ± 4 ゜. Numeral 12 is a cushion rubber, which is interposed between the belt layers 5, 5A.
f / cm ² or less, and tanδ is 0.20 or less,
The gauge thickness is 0.5 to 1.5 mm, and the width of the belt layer 5,5A is 2 /
3 or more. Therefore, the cushion rubber 12 may have the same width as the belt layers 5, 5A wider and narrower than this. Thus, the cushion rubber 12 and the under ply 11
Was interposed for the following reason. That is, when the vehicle gets over large unevenness, the tire is deformed to the shoulder portion and the sidewall portion, and a large shearing force is generated also in the two or more belt layers 5, 5A intersecting due to the deformation. This shearing force is transmitted from the bead portion to the rim through the carcass 4 forming the skeleton of the tire. Therefore, in order to reduce the above-mentioned shearing force, a soft and low-damping cushion rubber is provided between the belt layers 5, 5A.
12 are interposed. Further, since the shear force may be transmitted to the rim through the carcass 4 only by interposing the cushion rubber 12, the collision force and the shear force may be reduced in order to further reduce the collision force and the shear force.
When the underply 11 is β ゜ = α ゜ ± 4 or β ゜ = −α ゜ ±
The vibration damping effect is further enhanced by interposing under 4 mm. Here, the dynamic elastic modulus E ′ of the outer rubber layer 6 and the tan δ value of the inner rubber layer 7 are compared with the embodiment of the present invention and a comparative example (conventional example).
Table 1 below shows a comparison with Table 1. In the above Table 1, PP is the impact force at the time of riding over the protrusion,
λ also indicates the damping rate, and these indices are based on 100 based on the current tire (E'73 kg · f / cm ² , tan δ value 0.256). In the above table, the * mark indicates that the dynamic elastic modulus E 'is 35 kg.
・ F / cm ² and the case where a cushion rubber layer with a tan δ value of 0.163 was interposed, and the Δ mark indicates that the dynamic elastic modulus E ′ was 43 kg · f / cm ²
In the case where the tan δ value is interposed with the cushion rubber layer of 0.163, the mark ○ indicates the case where no cushion rubber layer is interposed, and the mark ▲ indicates that the dynamic elastic modulus E ′ is 43 kg · f / cm ² . tanδ
This shows a case where a cushion rubber layer having a value of 0.215 is interposed. As is clear from Table 1, the dynamic elastic modulus E 'of the outer rubber layer 6 is in the range of E' ≦ 50 kg · f / cm ² , and the tan δ value of the inner rubber layer 7 is in the range of tan δ ≧ 0.4. Sometimes, the impact input when the vehicle encounters unevenness is suppressed by the soft touch of the outer rubber layer 6 and is attenuated by the inner rubber layer 7, which shows that the ride comfort has been improved. Is done. Further, the cushion rubber 12 has a dynamic elastic modulus E '.
6 is less than 40 kg · f / cm ² , the vibration transmission is low by interposing a rubber having a tan δ value of 0.20 or less between the belt layers.
This can be understood from the example shown in FIG. In FIG. 6, A is the cushion rubber 12 having an E 'of 35 kg.
・ If tanδ value is 0.163 at f / cm ² , B is also 43kg ・ f / c
In the case of m ² and tan δ value: 0.163, in FIG.
Means that the cushion rubber 12 has an E 'of 35 kgf / cm ² and a tan δ value of 0.
163 and D show the case where E 'was 43 kg · f / cm ² and the tan δ value was 0.215. In both cases A and B, the E ′ of the outer rubber layer was 48 kg · f / cm ^2.
In cm ^2, tan [delta value of the inner rubber layer provides those 0.637,
For both C and D, E 'of the outer rubber layer was 43 kg · f / cm ² ,
The tan δ value of the inner rubber layer is 0.637. The tire conditions of the data in FIGS. 6 and 7 are as follows. Tire size 195 / 60R14 Tire internal pressure 2.0 kg · f / cm ² Tire load 320 kg · f Next, the relationship between the under ply 11 and the inside filler is shown in Table 2 below. However, in Table 2, E 'of the outer rubber layer 6 is 43 kg.
F / cm ² , the tan δ value of the inner rubber layer 7 is 0.637, the E ′ of the cushion rubber 12 is 35 kg · f / cm ² and the tan δ value is 0.163. In Table-2, when * 1 and * 2 do not insert an under ply, * 1 indicates PP99 and λ.
However, 98 and * 2 are PP-99 and λ97, and all except for * 1 and * 2 are shown with the under ply inserted. In Table-2, inside filler 10 is 200
% M 83kg ・ f / cm ² , under ply angle 0 ゜ (65
゜) The cornering power CP, the impact force and the damping rate when the vehicle goes over the protrusion are shown by PP, λ, the handling H by the actual vehicle feeling evaluation, and the riding comfort R by the five-point evaluation.
A rating of 5 or more is considered good. That is, the “CP” means Cornering Power. When a car turns, a frictional force is generated from the tires that balances the centrifugal force. This force is called the cornering force. This cornering force increases in proportion to the turning angle of the tire. The ratio of the cornering force to the turning angle of the tire at this time is called CP. The "H" means "Handling" and indicates the ease of handling. Generally, as a subjective evaluation method, a score of 5 out of 5 is regarded as normal, and if it is better, it is 3.5, 4.0... In 0.5 point increments, and if it is worse, it is evaluated as 2.5, 2.0. The above “R” means Ride Comfort, and represents good ride comfort. This is also the same as H, and the same evaluation is performed using a subjective evaluation method with 5 points out of 3 points and 3 points as normal. (Effects of the Invention) As described above, according to the present invention, in the pneumatic radial tire in which the tread portion is composed of a plurality of (including two or more) layers of the outer rubber layer and the inner rubber layer, the outer rubber layer has a dynamic elasticity. The impact on the road surface of the tire becomes soft because the rate E 'is E' ≦ 50 kg · f / cm ^2, and even if a large impact and deformation are applied to the tread portion of the tire when the road surface unevenness is encountered, The shock input can be made soft. Further, since the impact input is made soft by the outer rubber layer and the tan δ value of the inner rubber layer is set to tan δ ≧ 0.4, the impact force can be attenuated by the inner rubber layer. Further, since the soft rubber having a small E 'is used as the outer rubber layer of the tread portion, the riding comfort is improved, but the steering stability may be reduced. 80kg / f / c at% M
Insert the inside filler consisting of m ² or more hard rubber, since it is aimed to improve rigidity, it is possible to prevent the steering stability decreases. Further, in the present invention, the dynamic elastic modulus E 'is E' ≦ 40 kg · f / cm ² and the tan δ value ≦ 0.2 between the plurality of belt layers.
With a cushion rubber that is soft and has low damping properties, the impact force is attenuated by the inner rubber layer when riding over uneven road surfaces, and the large shear force generated in the belt layer is absorbed and the vibration transmitted to the rim is transmitted. Can be lower. Therefore, the present invention is significantly useful as a vehicle in which the riding comfort is greatly improved without impairing the tire steering stability, particularly as a passenger car.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention, FIG. 1 is a cross-sectional view showing a right half according to the first embodiment, and FIG. FIG. 3 is a cross-sectional view showing the right half of the second embodiment, FIGS. 4 and 5 are plan views showing the angle between the belt layer and the underply, and FIGS. It is a graph which shows a vibration conductivity. DESCRIPTION OF SYMBOLS 1 ... tire, 2 ... sidewall part, 3 ... tread part, 4 ... carcass, 5 ... non-extensible belt layer, 6 ...
... outer rubber layer, 7 ... inner rubber layer, 10 ... inside filler.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yuichiro Iwahashi 1-4-1, Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Shigeaki Suzuki 1-4-1, Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (56) References JP-A-61-295103 (JP, A) JP-A-61-229602 (JP, A) JP-A-53-4902 (JP, A) JP-A-59-206207 (JP, A) JP-A-57-18503 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60C 11/00 B60C 15/06 B60C 13/00

Claims (1)

(57) [Claims] A pair of sidewall portions (2) and a tread portion (3) extending between both sidewall portions (2) are toroidally connected, and each of these portions is arranged in a direction substantially orthogonal to the equatorial plane of the tire. A carcass (4) composed of at least one ply, a non-extensible belt layer (5) is arranged between the carcass (4) and the tread portion (3), and the tread portion (3) has a radius of a tire. In a pneumatic radial tire composed of a plurality of layers of an outer rubber layer (6) located outward in a direction and an inner rubber layer (7) located inward, the outer rubber layer (6) is dynamic. Elastic modulus E 'is E'≤50kg
F / cm ^2, and the inner rubber layer (7) has a loss tangent (tan δ),
The inside filler (10) provided inside the bead filler (9) provided in the bead portion and extended toward the vicinity of the shoulder portion is inserted into the sidewall portion (2), and is inserted into the sidewall (2). ) Is a pneumatic radial tire with improved riding comfort, characterized by rubber properties of 80 kg · f / cm ² or more with a 200% modulus. 2. A pair of sidewall portions (2) and a tread portion (3) extending between both sidewall portions (2) are toroidally connected, and each of these portions is arranged in a direction substantially orthogonal to the equatorial plane of the tire. A carcass (4) composed of at least one ply, a non-extensible belt layer (5) is arranged between the carcass (4) and the tread portion (3), and the tread portion (3) has a radius of a tire. In a pneumatic radial tire composed of a plurality of layers of an outer rubber layer (6) located outward in a direction and an inner rubber layer (7) located inward, the outer rubber layer (6) is dynamic. Elastic modulus E 'is E'≤50kg
F / cm ^2, and the inner rubber layer (7) has a loss tangent (tan δ),
The inside filler (10) provided inside the bead filler (9) provided in the bead portion and extended toward the vicinity of the shoulder portion is inserted into the sidewall portion (2), and is inserted into the sidewall (2). ) Has a rubber property of 80 kg · f / cm ² or more with a modulus of 200% and a belt layer (5) (5A) having a plurality of layers, and a dynamic elastic modulus E ′ between the layers is E ′. ≤40kg ・ f / cm
^2, and the loss tangent tan [delta The pneumatic radial tire soft and damping low cushion rubber layer in tanδ ≦ 0.2 (12) has improved riding comfort, characterized in that it is interposed.