JP4887707B2 - Vehicle and tire combination - Google Patents

Description

The present invention relates to a pneumatic tire in which a tire front and back mounting direction is specified when the vehicle is mounted, and more specifically, a vehicle capable of improving durability while suppressing increase in tire mass and deterioration in riding comfort. And a tire combination .

In recent years, with the increase in output and weight of vehicles, or improvement in the fashionability of vehicles, pneumatic tires have become wider, larger inner diameters and lower section heights (for example, patents). Reference 1). As a result, the air volume inside the tire has decreased, and the load factor on the tire has increased. In such a situation, it is difficult to sufficiently ensure the durability of the pneumatic tire, and troubles such as cord breakage of the carcass layer and interlayer separation tend to occur in the sidewall portion. In view of the increase in the load factor on the tire, durability can be improved by increasing the rubber gauge of the sidewall portion. However, when the rubber gauge of the sidewall portion is made thick, there is a disadvantage that the tire mass increases and the riding comfort deteriorates.
JP-A-9-249006

An object of the present invention is to provide a vehicle and tire combination that can improve durability while suppressing an increase in tire mass and deterioration in riding comfort.

In order to achieve the above object, the vehicle and tire combination of the present invention is a pneumatic tire in which the mounting direction of the front and back of the tire is specified when the vehicle is mounted, and the rubber gauge (Gi) on the side wall of the vehicle is set outside the vehicle. It is thicker than the rubber gauge (Go) of the side wall portion of the vehicle, and the relationship between the rubber gauge (Gi) of the side wall portion inside the vehicle and the rubber gauge (Go) of the side wall portion outside the vehicle is Go / Gi = 0.3-0. .9, and the rubber hardness (Hi) of the sidewall portion inside the vehicle is lower than the rubber hardness (Ho) of the sidewall portion outside the vehicle.

  As a result of earnest research on the cause of failure of a pneumatic tire having a low flatness ratio, the present inventor found that when the ground camber angle became negative due to a decrease in vehicle height due to loading or the like in the vehicle, the carcass layer in the sidewall portion inside the vehicle In view of the fact that there are many cases in which failures such as code breakage and interlayer separation occur, the present invention has been reached to deal with such typical failure occurrence situations.

  In other words, in the present invention, by selectively thickening the rubber gauge on the sidewall portion on the vehicle inner side where the failure occurrence frequency is high, the increase in the tire mass and the deterioration of the riding comfort are suppressed, and at the sidewall portion on the vehicle inner side. Prevents breakdowns and improves the durability of pneumatic tires. If the rubber gauge on the sidewall part inside the vehicle is simply thickened, the driving performance such as steering stability may be impaired due to the difference between the rigidity of the sidewall part inside the vehicle and the rigidity of the sidewall part outside the vehicle. However, it is possible to optimize the rigidity of both sidewall portions by reducing the rubber hardness of the sidewall portions inside the vehicle. However, the rigidity of both sidewall portions does not necessarily have to be equal, and the rubber hardness of both sidewall portions can be arbitrarily adjusted according to the required characteristics.

In the present invention, in order to achieve a higher level of weight reduction, riding comfort, and durability, the following configuration is preferably satisfied. That is, the relationship between the rubber gauge (Gi) of the sidewall portion inside the vehicle and the rubber gauge (Go) of the sidewall portion outside the vehicle is Go / Gi = 0.3 to 0.9 . Further, it is preferable that the rubber tan δ of the side wall portion inside the vehicle is lower than the rubber tan δ of the side wall portion outside the vehicle. Further, the height of the bead filler inside the vehicle is preferably lower than the height of the bead filler outside the vehicle.

  In the present invention, the rubber gauge (Gi, Go) of the sidewall portion means the average thickness of the rubber layer covering the outside of the carcass layer in the sidewall portion. More specifically, it is the average thickness of the rubber layer existing in the region from the design end of the tread portion to the height position of the rim flange in a state where the pneumatic tire is fitted to the standard rim. The thickness of the rubber layer is measured in a direction perpendicular to the adjacent carcass layer. The rubber hardness (Hi, Ho) of the sidewall portion means the JIS-A hardness at 20 ° C. of the rubber layer covering the outside of the carcass layer in the sidewall portion. The rubber tan δ in the sidewall portion means a loss tangent at 60 ° C. of the rubber layer covering the outside of the carcass layer in the sidewall portion. The loss tangent is measured using a viscoelastic spectrometer under conditions of a temperature of 60 ° C., a frequency of 20 Hz, an initial strain of 10%, and a dynamic strain of ± 2%.

  The present invention is particularly preferably applied to a pneumatic tire having a tire cross-section height of 120 mm or less and a flatness ratio of 55% or less. Thus, when the said structure is employ | adopted for the pneumatic tire with a low flat rate, the remarkable improvement effect can be acquired about durability.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a pneumatic tire according to an embodiment of the present invention. The pneumatic tire of the present embodiment has a tire cross-section height SH of 120 mm or less and a flatness ratio of 55% or less, and the mounting direction of the tire front and back when the vehicle is mounted is designated. The vehicle inner side when the vehicle is mounted is indicated by IN, and the vehicle outer side when the vehicle is mounted is indicated by OUT.

  In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 made up of a plurality of aligned carcass cords is mounted between the pair of bead portions 3 and 3. Both ends of the carcass layer 4 are wound around the bead core 5 from the inside of the tire to the outside of the tire. A bead filler 6 made of high-hardness rubber is disposed on the outer periphery of the bead core 5, and the bead filler 6 is wrapped by the carcass layer 4. A chafer 7 is disposed in the bead portion 3 so as to cover at least a portion from the bead toe to the bead heel. On the other hand, a belt layer 8 including a reinforcing cord that is inclined with respect to the tire circumferential direction is disposed on the outer peripheral side of the carcass layer 4 in the tread portion 1. Further, a belt cover layer 9 including reinforcing cords oriented in the tire circumferential direction is disposed on the outer peripheral side of the belt layer 8.

  In the pneumatic tire, a tread rubber layer 11 is disposed on the outer side of the carcass layer 4 and the belt layer 8 in the tread portion 1, and side wall rubber is disposed on the outer side of the carcass layer 4 in the sidewall portion 2. A layer 12 is disposed, and a rim cushion rubber layer 13 is disposed in a region outside the carcass layer 4 in the region from the sidewall portion 2 to the bead portion 3.

  Here, the rubber gauge (Gi) of the sidewall portion 2 inside the vehicle is thicker than the rubber gauge (Go) of the sidewall portion 2 outside the vehicle. As shown in FIG. 1, the rubber gauges (Gi, Go) are designed in the tire width direction of the design end of the tread portion 1 (the groove pattern including the main groove 21 and the lug groove 22) when the pneumatic tire is fitted to the standard rim. This is the average thickness of the rubber layer in the region X from the outer end) to the height position of the rim flange F. The rubber gauges (Gi, Go) of these sidewall portions 2 define the average thickness, but considering the resistance to damage, the lower limit value of the local rubber thickness is preferably 1.5 mm. Further, in addition to the rubber gauges (Gi, Go) being asymmetric, the rubber hardness (Hi) of the sidewall portion 2 inside the vehicle is lower than the rubber hardness (Ho) of the sidewall portion 2 outside the vehicle. .

  As described above, by making the rubber gauge (Gi) of the sidewall portion 2 inside the vehicle thicker than the rubber gauge (Go) of the sidewall portion 2 outside the vehicle, while suppressing an increase in tire mass and deterioration in riding comfort, It is possible to prevent a failure in the sidewall portion 2 inside the vehicle and improve the durability of the pneumatic tire. When the rubber gauge (Gi) of the sidewall portion 2 inside the vehicle is simply increased, driving stability and the like are caused by the difference between the rigidity of the sidewall portion 2 inside the vehicle and the rigidity of the sidewall portion 2 outside the vehicle. Although the performance may be impaired, the rigidity of both sidewall portions is reduced by making the rubber hardness (Hi) of the sidewall portion 2 inside the vehicle lower than the rubber hardness (Ho) of the sidewall portion 2 outside the vehicle. It is possible to optimize.

  In the pneumatic tire, the relationship between the rubber gauge (Gi) of the sidewall portion 2 inside the vehicle and the rubber gauge (Go) of the sidewall portion 2 outside the vehicle is preferably set to Go / Gi = 0.3 to 0.9. If the rubber gauge (Go) is less than 30% of the rubber gauge (Gi), it will be difficult to adjust the rigidity by the rubber hardness. Conversely, if the rubber gauge (Gi) exceeds 90% of the rubber gauge (Gi), the effect of reducing weight and improving riding comfort will be reduced. . It is desirable that the rubber gauge (Gi) of the sidewall portion 2 inside the vehicle is 1.7 mm to 12.0 mm, and the rubber gauge (Go) of the sidewall portion 2 outside the vehicle is 1.5 mm to 10.5 mm.

  On the other hand, the relationship between the rubber hardness (Hi) of the sidewall portion 2 inside the vehicle and the rubber hardness (Ho) of the sidewall portion 2 outside the vehicle is preferably Ho−Hi = 3-20. In particular, the rubber hardness (Hi) of the sidewall portion 2 on the vehicle inner side is preferably 40 to 64, and the rubber hardness (Ho) of the sidewall portion 2 on the vehicle outer side is preferably 48 to 70.

  The rubber tan δ of the sidewall portion 2 on the vehicle inner side is preferably lower than the rubber tan δ of the sidewall portion 2 on the vehicle outer side. By suppressing the heat generation due to the loss energy in the sidewall portion 2 inside the vehicle, a failure in the sidewall portion 2 inside the vehicle can be suppressed.

  Furthermore, the height of the bead filler 6 on the vehicle inner side is preferably lower than the height of the bead filler 6 on the vehicle outer side. By reducing the height of the bead filler 6 inside the vehicle, local deformation of the side wall portion 2 inside the vehicle when a load is applied can be suppressed, and cord breakage and interlayer separation of the carcass layer 4 can be prevented. it can.

  For pneumatic tires of tire size 245 / 40R18, tires of conventional examples, examples 1 to 3 and comparative examples, in which only the rubber gauges (Gi, Go) and rubber hardness (Hi, Ho) of the sidewall are varied, are manufactured. did.

  About these test tires, riding comfort and load durability were evaluated by the following test methods, and the results are also shown in Table 1.

Ride comfort:
The test tire was fitted to a wheel with a rim size of 18 × 8 J and mounted on a vehicle with a displacement of 5000 cc, and sensory evaluation was performed by a driver under the condition of an air pressure of 230 kPa. The evaluation results are shown as an index with the conventional example being 100. A larger index value means better ride comfort.

Load durability:
An indoor drum durability test was performed on the test tire. In the indoor drum endurance test, the load was 151% of the load capacity, the air pressure was 330 kPa, the camber angle was −3 °, and the speed was 81 km / h. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the load durability.

  As shown in Table 1, the tires of Examples 1 to 3 had significantly improved load durability while having a riding comfort equal to or higher than that of the conventional example. On the other hand, since the tire of the comparative example has an effect of improving the load durability by increasing the rubber gauges of both side wall portions, the riding comfort has deteriorated in exchange.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Chafer 8 Belt layer 9 Belt cover layer 11 Tread rubber layer 12 Side wall rubber layer 13 Rim cushion rubber layer 21 Main groove 22 Lug groove Gi Vehicle Rubber gauge on the inner side wall part Go Rubber gauge on the outer side wall part of the vehicle IN Vehicle inner side OUT Vehicle outer side SH Tire cross-section height

Claims (4)

In a pneumatic tire with the direction of mounting the front and back of the tire when the vehicle is mounted, the rubber gauge (Gi) of the sidewall portion inside the vehicle is thicker than the rubber gauge (Go) of the sidewall portion outside the vehicle, The relationship between the rubber gauge (Gi) of the wall portion and the rubber gauge (Go) of the sidewall portion outside the vehicle is Go / Gi = 0.3 to 0.9, and the rubber hardness (Hi) of the sidewall portion inside the vehicle is the vehicle. A vehicle and tire combination that is lower than the rubber hardness (Ho) of the outer sidewall. The vehicle and tire combination according to claim 1 , wherein the rubber tan δ of the sidewall portion inside the vehicle is lower than the rubber tan δ of the sidewall portion outside the vehicle . Vehicle and tire combination as set forth in any one of claims 1-2 for the height of the bead filler on the vehicle inner side is set lower than the height of the bead filler on the vehicle outer side. The vehicle and tire combination according to any one of claims 1 to 3 , wherein a tire cross-section height is 120 mm or less and a flatness ratio is 55% or less.

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