JPH09286209A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the transmission of human power to a vehicle body by disposing a rubber sheet 7 whose loss tangent tanδ is less than a specified value at a specified temperature and whose thickness is in a specified range in the outside in the axial direction of the tire of the innermost side of carcass layers. SOLUTION: A tire 1 comprises a pair of side walls 2, a tread portion 3, and a carcass 5 having an end wound around a bead ring 4 buried in the top of the side wall 2. A belt 6 is disposed in the crown portion of the carcass 5 between the tread portion 3 and the carcass 5. A rubber sheet 7 whose loss tangent tanδ in over 60 when the temperature is 25 deg.C is disposed at the place of 55mm from a bead base line in the outside in the axial direction of the tire of the innermost carcass 5 of the carcass layers. The thickness of the rubber sheet 7 is over 0.8mm and under 4.0mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire having improved noise and riding comfort.

[0002]

2. Description of the Related Art Noise generated from tires during traveling is related to the condition of a traveling road surface, and the vibration is transmitted through a vehicle body to affect a driver or a passenger in a vehicle cabin.
Road noise of 0 to 500 HZ) and noise of a wider frequency band radiated from tires into the atmosphere are known. Especially, the latter is associated with the surrounding environment with the recent development of motorization. It has become a serious social problem because it has a large impact on In addition, input from the tire contact surface when passing through road joints or steps is transmitted to the vehicle body through the carcass layer, sidewalls, etc. and is given to the driver and passengers in the vehicle interior, so it is necessary to expand the expressway network in recent years. As the vehicle speed increases, the influence of the increase in vehicle speed also increases, and there is a growing demand for improved ride comfort.

The noise is related to the tread pattern engraved on the tread portion of the tire, and is caused by the pitch component, that is, when the tread portion passes through the ground contact surface, it is mainly due to compression / expansion of air in the groove. The radiated sound due to the vibration of the resulting air and the radiated sound based on the vibration of the entire tread portion including the belt layer and the carcass layer embedded inside the tread portion are included. It is widely known that the noise due to the pitch component can be reduced by using the pitch variation method when designing the pattern. On the other hand, in order to reduce the noise due to the vibration of the tread portion, it has been considered effective to make the gauge of the tread rubber thick and to additionally arrange a cord reinforcing layer around the belt layer. However, thickening the gauge of the tread rubber not only deteriorates rolling resistance, but also lowers shear rigidity of the tread portion, which deteriorates steering stability. In addition, the addition of the cord reinforcing layer has a problem that the interlayer shear strain of the belt portion is increased and rolling resistance is deteriorated. On the other hand, ride comfort is to reduce the rigidity of the carcass layer and sidewalls because the input from the tire contact surface when passing through seams and steps on the road is transmitted to the vehicle body through the carcass layer and sidewalls. Although it is possible to suppress the transmission of the input to the vehicle body and improve the ride comfort, there is a problem that the steering stability is reduced. The noise caused by the vibration of the tread part is greatly affected by the vibration transmitted from that part to the carcass layer, the sidewall, etc.
In order to improve ride comfort, it is effective to suppress transmission of input to the vehicle body by improving the carcass layer and the sidewall as described above. As described above, in order to improve the noise and the riding comfort, it is possible to effectively suppress the transmission of the input to the vehicle body by improving the carcass layer, the sidewall, and the like. Accordingly, Japanese Patent Laid-Open No. 2-2081
03 and Japanese Patent Application Laid-Open No. 5-270207, etc., in which the damper sheet is disposed on the side wall portion, and a rubber sheet having high hardness is disposed in a portion sandwiched between the belt and the carcass, thereby improving ride comfort and noise. Although there is an invention, the effect did not sufficiently satisfy users and the like.

[0004]

DISCLOSURE OF THE INVENTION The inventor has made an input by improving a carcass layer, a sidewall and the like in order to sufficiently improve noise and riding comfort without lowering rolling resistance and steering stability. The purpose was to effectively suppress the transmission of the vehicle to the vehicle body.

As described above, in order to improve the noise and the riding comfort, it is effective to suppress the transmission of the input to the vehicle body by improving the carcass layer, the side wall, etc., as described above. As a result of examining the cause that could not be achieved by the conventional technique, it was decided to improve the arrangement position, thickness and material of the vibration damping sheet.

[0006]

According to the present invention, at least one radial ply carcass layer is provided between the bead cores embedded in a pair of bead portions and between the bead portions to reinforce the pair of sidewall portions and the tread. A tire provided with, in the range from the bead heel in the tire radial direction to the axially outer end of the belt layer, the loss tangent at 25 ° C outside the carcass layer on the innermost tire side of the carcass layer in the axial direction of the tire. tan δ is 0.
A pneumatic radial tire, wherein a rubber sheet having a thickness of 60 or less is arranged, and the thickness of the rubber sheet is 0.8 mm or more and 4.0 mm or less.

The inventor has found out that most of the vibrations are transmitted to the vehicle body along the carcass layer, and examined the effective arrangement position of the rubber sheet for vibration damping in order to suppress the transmission. As a result, it was clarified that disposing the rubber sheet for vibration damping in the portion where the carcass has high tension has a transmission suppressing effect. Specifically, since the carcass is given a tension by the internal pressure at the time of the internal pressure, the rubber sheet for vibration damping is arranged more outward than the inner side in the tire axial direction of the carcass closest to the tire inner surface side in the carcass layer. It is more effective.

Further, in the range from the bead heel in the tire radial direction to the axially outer end of the belt layer (so-called side portion), the vibration absorbing rubber sheet is arranged at a portion where the tension of the carcass is intentionally increased. By that,
It turned out to have a remarkable effect. Generally, the carcass line, which is the locus of the carcass, is often set to a natural equilibrium shape or a shape close to it, so a rubber sheet with sufficient thickness as described above should be placed on the innermost tire side of the carcass layer. By arranging the carcass on the outer side from the inner side in the tire axial direction, at the time of vulcanization molding, the portion on which the rubber sheet is arranged is at least the innermost carcass of the tire as compared to other portions. Since the carcass line of the portion where the rubber sheet is placed is locally moved from the other portion to the tire meridian cross section after the vulcanization because the carcass line is moved to the tire inner surface side from the natural equilibrium shape or a shape close to it in the meridional section. It will be located closer to the inner surface of the tire. Therefore, after the internal pressure filling, the carcass layer is given a tension by the internal pressure, and the carcass line changes to a natural equilibrium shape or a shape close to it, so that the portion where the rubber sheet is arranged is different from the other portions before and after the internal pressure filling. Since the moving distance in the meridional section of the tire becomes large, the tension of the carcass inevitably becomes high. Therefore, a remarkable improvement effect can be obtained. Here,
The rubber sheet having a sufficient thickness means a sheet having a thickness of 0.8 mm or more.

The thickness of the rubber sheet is 0.8 mm.
Even after the following, after assembling on the rim of the specified rim width of the tire, from the time of pneumatic filling at maximum load capacity to 5% of maximum tire load capacity or at 0.3 kgf / cm ² whichever is larger. When the carcass tension is changed, the carcass tension is locally increased by changing the shape of the carcass on the tire meridional section, which is changed by a means such as JP-A-3-74209 or Japanese Patent Publication No. 8-9281. By arranging the rubber sheet at a position where the height is increased, a remarkable effect is obtained. Specifically, after assembling the tire to a rim having a specified rim width of the tire, the tire is loaded at a maximum load capacity of 5 times from the time of pneumatic pressure filling to the tire maximum load capacity.
% Or 0.3 kgf / cm ² when changing to pneumatic filling, the carcass movement distance in the meridional section of the tire at the place where the vibration damping sheet is arranged in the side part is a (mm), and the side part When the maximum moving distance of the carcass in the meridional section of the tire other than the position where the vibration damping sheet is arranged is b (mm), a
It is preferable that a / b, which is the ratio of b and b, is 1.3 or more.

Usually, when a rubber sheet or the like is arranged on the side portion and the rubber gauge is increased, the rolling resistance is deteriorated. Therefore, as a result of examining the material of the rubber sheet, the thickness of the rubber sheet is 4 mm or less,
It was also found that if the loss tangent tan δ at 25 ° C is 0.60 or less, the rolling resistance does not deteriorate. The measurement of the loss tangent tan δ here is that the initial strain of each sample is 10
%, Frequency 50 Hz, dynamic strain 1.0%, and temperature 25
The measurement was carried out using a spectrometer T-1000 manufactured by Toyo Seiki under the conditions of °.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In order to confirm the above effects, several pneumatic radial tires having a tire size of 195 / 65R15 were prepared, and a test tire was assembled on a 5.5J × 15 rim to obtain 1.8kgf / The inside pressure of cm ² was filled, and the following tests were carried out indoors or in an actual vehicle.

First, as a rolling resistance test, the test tire was pressed against a drum having a diameter of 1707 mm while being loaded with a load of 400 kg, and the tire was coasted from a speed of 200 km / h.
The rolling resistance was calculated from the degree of the speed during rotation. still,
In the evaluation, the conventional tire was set to 100 and the other test tires were indicated by indices.

Next, in a ride comfort test, an actual vehicle was run on a test course at a speed of 40 to 80 km / h on a stepped road surface, a seam road surface, a Belgian road, etc., and the feeling of the test was evaluated by a test driver. The evaluation was based on a 10-point scale.

In addition, in the actual vehicle on the asphalt road
In accordance with JASO C606-81 standard, steady running noise was measured at a speed of 52 km / h, and the difference in passing noise from the conventional tire is displayed in dB.

Finally, a steering stability test was performed. On the test course, the actual vehicle traveled straight at a speed of 60 to 120 km / h, changed lanes, and turned a circle to evaluate the feeling by the test driver. The evaluation was made by the 10-point scale, as in the above-mentioned riding comfort test.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a partial sectional view of a tire showing Example 1 of the present invention. In the figure, a tire 1 has a pair of side walls 2 and a tread portion 3 extending in a cylindrical shape across both side walls 2.
Are connected in a toroidal shape, and a carcass 5 having an end wound around a bead ring 4 embedded at the tip of the side wall 2 is formed into a side wall 2 and a tread portion 3.
The belt 6 extending through the region of the carcass 5 and the tread 3 at the crown portion of the carcass 5 extends over the width of the tread. Carcass 5
It consists of one ply in which polyester (rayon, nylon, etc. can be substituted) fiber cords are arranged at approximately 90 ° (radial) with respect to the equatorial plane O, and the belt layer is made of steel or aramid. Two belt plies in which non-stretchable cords, etc., are inclined with respect to the equatorial plane O at an angle of 24 ° are superposed so that the cords cross each other.

Example 1 In Example 1, as shown in FIG. 1, a vibration damping sheet having a tan δ of 0.55, a thickness of 0.8 mm and a width of 30 mm is arranged at a distance P from the bead baseline of 55 mm. Let After assembling the rim of the tire of the specified rim width of the tire,
0.3kgf / cm from pneumatic filling at maximum load capacity
^2. When changing to the time of pneumatic filling, the moving distance of the carcass in the meridional section of the tire at the location where the vibration damping sheet is arranged in the side portion is set to a (mm), and the vibration damping sheet is arranged in the side portion. When the maximum moving distance of the carcass in the meridional section of the tire at a position other than the above was set to b (mm), the ratio a / b, which is the ratio of a to b, was 1.3. -Example 2 Example 2 was the same as Example 1 except that the thickness of the vibration absorbing sheet was 3.0 mm and the a / b was 1.6. -Example 3 Example 3 was the same as Example 1 except that the thickness of the vibration absorbing sheet was 4.0 mm and the a / b was 1.8. -Example 4 In Example 4, the thickness of the vibration-damping sheet was 0.7 mm. As a result of applying the shape as shown in FIG.
The same as Example 1 except that b was 3.0. Comparative Example 1 Comparative Example 1 is the same as Example 1 except that the vibration damping sheet has a tan δ of 0.65, a thickness of 3.0 mm, and a / b, which is the ratio of a to b, of 1.6. It was similar. Comparative Example 2 Comparative Example 2 was the same as Example 1 except that the vibration damping sheet had a thickness of 0.6 mm and the a / b was 1.0. Comparative Example 3 Comparative Example 3 was the same as Example 1 except that the thickness of the vibration absorbing sheet was 4.5 mm and the a / b was 2.0. -Conventional example The conventional example was the same as that of the example 1 except that the vibration absorbing sheet was not arranged.

The results of the tests conducted on the above-mentioned test tires are shown in Table 1 below.

[0019]

[Table 1]

[0020]

INDUSTRIAL APPLICABILITY As described above, in order to sufficiently improve the noise and the riding comfort without lowering the rolling resistance and the steering stability, the input is transmitted to the vehicle body by improving the carcass layer and the sidewall. Can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view of a left half of a tire showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a left half of a tire showing a fourth embodiment of the present invention.

[Explanation of symbols]

 1 tire 2 sidewall 3 tread 4 bead core 5 carcass 6 belt 7 rubber sheet

Claims (2)

[Claims] 1. A tire having a carcass layer of at least one radial ply which extends between bead cores embedded in a pair of bead portions and reinforces a pair of sidewall portions continuous with the bead portions and a tread, the tire radius being In the range from the bead heel to the axially outer end of the belt layer, the loss tangent tan δ at 25 ° C. is 0.60 or less outside the carcass layer on the innermost tire side of the carcass layer in the axial direction of the tire. A pneumatic radial tire in which a certain rubber sheet is arranged, and the thickness of the rubber sheet is 0.8 mm or more and 4.0 mm or less. 2. A tire having a carcass layer of at least one radial ply that reinforces a pair of sidewall portions connected to the bead portions and a tread across bead cores embedded in the pair of bead portions, the tire radius being a tire radius. In the range from the bead heel to the axially outer end of the belt layer, the loss tangent tan δ at 25 ° C. is 0.60 or less outside the carcass layer on the innermost tire side of the carcass layer in the axial direction of the tire. And the thickness of the rubber sheet is 4.0
After arranging a rubber sheet having a size of less than or equal to mm, and assembling to a rim having a specified rim width of the tire, 5% of the maximum tire load capacity or 0.3 kgf / cm ² whichever is greater, from the time of pneumatic filling at maximum load capacity When changing to the time of pneumatic filling, the moving distance of the carcass in the tire meridional section of the portion where the vibration damping sheet is arranged is a (mm), and the tire at the portion other than where the vibration damping sheet is arranged in the side portion The maximum movement distance of the carcass in the meridional section is b
(Mm), a / b, which is the ratio of a and b, is 1.
Pneumatic radial tire characterized by being 3 or more.