JPH06143927A - Pair of pneumatic tire combining grip force and rigidity feeling of front and rear wheels - Google Patents

Abstract

PURPOSE:To provide pairs of pneumatic tires combining a grip force and rigidity feeling in a use temperature region for front and rear wheels of high performance automobile. CONSTITUTION:Assuming that the tangent of loss and stored elastic modulus of tread rubber of front and rear wheel tires are tandelta (F), Es (F) and tandelta (R) and Es (R), the relation of 0.5<tandelta (F)<tandelta (R); 1.0X10<8>dyn/cm<2Es (F); 1.0X10<8>dyn/cm<2Es (R) shall be satisfied in 30 deg.C., while the relation of 0.85<=tandelta (F)/tandelta (R)<=0.95; 0.9<=Es(F)/Es (R)<=1.1 shall be satisfied in 30 deg.C or more and 100 deg.C or less of temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a pair of front wheels and rear wheels for use in vehicles capable of high-speed running, in particular sports cars or racing cars, etc., which are required to have high dynamic performance. It relates to a pneumatic tire pair.

[0002]

2. Description of the Related Art In recent years, high-speed driving performance of automobiles has been remarkably advanced, and along with this, advanced tires equipped with these automobiles have been used for tires which determine the final maneuverability and stability of the automobile. There is an increasing demand for higher performance so that exercise performance can be fully exhibited. Especially, in a sports car that requires outstanding steering stability performance when driving including cornering, or in a racing car that competes for 1/10 seconds by using advanced running methods, the exercise performance that the tires used can demonstrate is It's a serious problem.

The above-mentioned problem of tire dynamic performance mainly occurs during cornering and lane change. The first problem is that the grip force of the front tires and the grip force of the rear tires on the road surface cannot always maintain a suitable balance. For example, if the grip force of the front tires is significantly higher than that of the rear tires, the rear wheels will skid and the vehicle will be extremely oversteered, which may cause a spin. In the opposite case, strong understeer results, resulting in a lack of sporty running and more time lost in the race.

The second problem is that the rigidity of front and rear tires is not uniform. The sense of rigidity means the responsiveness of the vehicle during steering according to the driver's feeling and the sharpness of the steering wheel. Unless the front and rear wheels have a uniform sense of rigidity and the level is not maintained at a high level, the driver cannot expect and drive the desired vehicle. As a result, similar to the above, sporty driving cannot be performed, and in the case of a race, loss time increases.

Conventionally, attempts have been made to deal with the above problems mainly in terms of structure, for example, by devising belt rigidity and sidewall rigidity.

Further, there is Japanese Patent Laid-Open No. 190504/1989 as a prior art which is thought to lead to the solution of the above problems. In this technique, the front tires and the rear tires have different tread patterns, and the tires having the negative ratio of the front tires to the rear tires are mounted in combination.

Further, in relation to the above, Japanese Patent Laid-Open No. 3-1972
There is No. 05 publication. This disclosed technology uses different tires for the front and rear wheels, the relationship between the loss tangent of the rubber of the tire tread of each of the front and rear wheels, the relationship between the pitch number and the loss tangent together with the regulation of the pitch number of each tread pattern, and It shows the hardness of the tread rubber.

[0008]

Since the above-mentioned structural countermeasure technique does not take up the tread rubber in contact with the road surface, it is possible to cope with changes in road surface conditions and tire temperatures, particularly temperature changes in the tread portion. As a result, there has been a problem that it is not possible to match and balance the gripping force and the rigidity at a high level of the front and rear tires in various running methods.

The technique disclosed in Japanese Patent Application Laid-Open No. 1-195050 is different from the conventional one in that the same excellent high-speed turning performance can be obtained even on a wet road surface as on a dry road surface by changing the negative ratio of the tires of the front and rear wheels. Superior to technology. However, this technique can balance the grip and rigidity of the tires of the front and rear wheels in the pattern, but since the tread rubber itself is not taken into consideration, there is still an unacceptable limit to these balances, There was a problem that it could not be adapted to the running method of the vehicle, which requires a higher degree of movement performance.

The technique disclosed in Japanese Patent Laid-Open No. 3-197205 takes a step forward in that the loss tangent of the tread rubber of the tires on the front and rear wheels is taken into consideration. But this technology
With the aim of achieving a high degree of steering stability with the value of the loss tangent at one point of 60 ° C and the value of hardness at room temperature, the temperature dependence of the tread rubber, that is, the rubber physical properties associated with the temperature change of each tread of the front and rear tires. Is not taken into account.

For this reason, the balance of the grip force and the feeling of rigidity of the front and rear wheel tires is lost due to the temperature difference between the start and the middle of the running, the temperature change during the running, the difference in the outside air temperature, etc., and of course the dry road surface on the wet road surface. However, there was a problem that the desired higher exercise performance could not be exhibited. Further, since this technique represents the rigidity of the tread rubber by the static hardness, there is a problem that it does not match the dynamic transient characteristics of the tire.

Therefore, an object of the present invention is to allow the sports car or racing car to fully exhibit its higher-level transient motion performance under the ambient temperature change as well as the tread rubber temperature change. According to various running conditions on both wet and dry road surfaces, the pneumatic tire paired with the front and rear wheels is capable of exerting a high degree of grip and rigidity of the front and rear tires and appropriately balancing them. Is to propose.

[0013]

In order to achieve the above-mentioned object, a pneumatic tire pair according to the present invention, which has a grip and a sense of rigidity of front and rear wheels, has a front tire and a rear tire in a mounted state of an automobile. The tread rubbers have different qualities, the loss tangent and storage elastic modulus of the tread rubber of the front tire are tan δ (F) and Es (F), and the loss tangent and storage elastic modulus of the tread rubber of the rear tire are tan δ.
(R) and Es (R), the loss tangent and the storage elastic modulus of these tread rubbers are 0.5 <tan δ (F) <tan δ (R); 1.0 × 10 ^{8 at} 30 ° C. dyn / cm ² <Es (F); 1.0 × 10 ⁸ dyn / cm ² <Es (R); and in the temperature range of 30 ° C. or higher and 100 ° C. or lower, 0.85 ≦ tan δ (F) / tan δ (R) ≦ 0.9
5; 0.9 ≦ Es (F) / Es (R) ≦ 1.1;

The present invention will be described more specifically below. First, the pair of pneumatic tires of the present invention is a pair of tires mounted on the front wheels and tires mounted on the rear wheels, and the treads of the front wheel mounted tires and the rear wheel mounted tires are made of different rubber materials.

Hysteresis loss is a loss tangent and is represented by tan δ as one representative characteristic of the dynamic viscoelasticity of the tread rubber in each of the above tires, and the dynamic elastic modulus is a storage elastic modulus as the other representative characteristic. It is represented by. The loss tangent of the tread rubber of the front tire is represented by tan δ (F), the storage elastic modulus is represented by Es (F), and the loss tangent of the rear tire is represented by tan δ (R), and the storage elastic modulus is represented by Es (R).
It is well known that tan δ is a value obtained by dividing the loss elastic modulus El by the storage elastic modulus Es.

The loss tangent value and the storage elastic modulus value at each temperature of 30 ° C. of the tread rubbers of the front wheel-mounted tire and the rear wheel-mounted tire satisfy the following relationship. 0.5 <tan δ (F) <tan δ (R); 1.0 × 10 ⁸ dyn / cm ² <Es (F); 1.0 × 10 ⁸ dyn / cm ² <Es (R).

In addition to the above relationship, the loss tangent value and the storage elastic modulus value of each tread rubber over the temperature range of 30 ° C to 100 ° C always satisfy the following relationship in this temperature range. It is a thing. 0.85 ≦ tanδ
(F) / tan δ (R) ≦ 0.95; 0.9 ≦ Es (F) / Es (R) ≦ 1.1.

The pneumatic tire paired with the front and rear wheels of the present invention is required to satisfy the above-mentioned relationship at 30 ° C. in the physical relationship between the tread rubbers of the front tire and the rear tire mounted on the vehicle. However, this is not sufficient alone, and at the same time, the object can be sufficiently achieved only when the above relationship in the temperature range of 30 ° C. to 100 ° C. is satisfied.

The loss tangent value and the storage elastic modulus value are values obtained by measurement under the following conditions. That is, a rubber test piece having a length of 20 mm, a width of 4.7 mm, and a thickness of 2 mm was cut out from an actual tire tread, and this rubber test piece was attached to a viscoelasticity measuring device, and then the initial tension was applied to the rubber test piece. 1.7 kgf / cm ² was applied, and in this state, a vibration having a frequency of 50 Hz and an amplitude distortion of 2% was applied to the rubber test piece, and the ambient temperature was initially set to 20 ° C and the temperature was raised at a rate of 1 ° C per minute. The measurement is performed while performing the process up to 100 ° C.

[0020]

First, in order to enhance the grip and rigidity of the front and rear tires to a high degree, and at the same time to match the grip and rigidity of the front and rear tires, the temperature is set to 30 ° C.
The dynamic viscoelasticity of each tread rubber in Table 1 was used as the basis of the characteristic value. The value at 30 ° C. is used because the characteristic value of the dynamic viscoelasticity of rubber at this temperature has the closest correlation to the above characteristic in the actual use state of the tire.

At 30 ° C., tan δ (R) of the tread rubber of the rear tire is calculated as t of the tread rubber of the front tire.
When the value exceeds an δ (F), it is possible to maintain the balance by appropriately adjusting the gripping force of the front and rear tires in a running state, particularly in a curve running at a high speed, and thereby maintaining a weak understeer tendency. It is possible to If the values of these loss tangents are matched, or if they are reversed, the grip force of the front tires will greatly exceed the grip force of the rear tires, which causes the vehicle to exhibit a strong oversteer tendency and the vehicle to spin. Causing a risk of steering failure.

Also, tan δ of the tread rubber of the front tires
When (F) is set to a value exceeding 0.5, high gripping force can be exerted on each of the front and rear tires. This is particularly effective on wet road surfaces. If this value is 0.5 or less, the desired grip force cannot be obtained.

Next, the storage elastic moduli Es (F) and Es (R) of the tread rubbers of the front and rear tires are both 1.0 ×.
When the value exceeds 10 ⁸ , high rigidity can be imparted to the tread in the transitional state, and the front and rear tires can exhibit a high rigidity feeling during steering. As a result, it is possible to obtain desirable vehicle responsiveness and steering wheel sharpness. Es (F) and Es
If the value of (R) is 1.0 × 10 ⁸ or less, these desirable performances cannot be obtained and it is impossible.

These three relationships at 30 ° C.
In any case, it is the basis for enabling the exertion of a high degree of transient motion performance mainly in the turning motion.In addition to this, the present invention responds to the temperature change of the tread rubber as described below. And the performance to match the grip and rigidity of the front and rear tires.

Further, in order to prevent the balance of the grip force of the front and rear tires from being lost due to the temperature change, particularly the change in the tire characteristics due to the temperature rise of the tire, first, at 30 ° C.
In the temperature range from 100 to 100 ° C., the degree of temperature dependence of tan δ of each tread rubber of the front and rear tires is adjusted, and the value of tan δ (F) / tan δ (R) is set to 0.
It falls within the range of 85 or more and 0.95 or less. If the value of this ratio is less than 0.85, the grip force of the rear tires becomes relatively small, and the tendency of understeering becomes strong, and the steering effect of the vehicle decreases, which is not preferable. Further, when the value of this ratio exceeds 0 ° 95, the grip force of the rear tires becomes relatively small, the tendency of oversteering of the vehicle becomes strong, the rear part of the vehicle does not fit well during steering, and the risk of spin increases. Is impossible.

Secondly, in the temperature range of 30 ° C. to 100 ° C., the temperature dependence of Es of each tread rubber of the front and rear tires is determined so that the value of Es (F) / Es (R) is 0.9 or more. By making it fall within the range of 1.1 or less, it becomes possible to match the rigidity of the front and rear tires. This makes it possible to stabilize the behavior of the vehicle while maintaining the responsiveness of the vehicle during steering and the sharpness of the steering wheel at a high level. If the value of Es (F) / Es (R) is less than 0.9, the rigidity of the front tires is insufficient, and as a result, the vehicle tends to understeer, which is not preferable. If this value exceeds 1.1, the rigidity of the rear tires becomes insufficient, the vehicle tends to oversteer, and the vehicle exhibits unstable and dangerous behavior during steering, which is not preferable.

The range of temperature change is 30 ° C to 100 ° C
The range is set because the temperature distribution of the tread rubber from the initial stage to the middle stage and the final stage of running is represented by this temperature range.

[0028]

Example: Both front and rear tires are 205 / 60R1 in size
A pneumatic tire for passenger cars, which is No. 5, is selected. Three tires are used in the examples. Moreover, in order to verify the effect of each tire of the example, tires of comparative examples having the same size of 7 examples were prepared. Table 1 shows the values of tan δ and Es at 30 ° C., 60 ° C. and 100 ° C. from the rubbers (A) to (H) used for the tread of these tires.

[0029]

[Table 1]

Table 2 shows the rubbers of the tire treads of the front wheels and the rear wheels of the tires of Examples 1 to 3 and Comparative Examples 1 to 7, respectively. ) To (H) are used in the section of (front wheel / rear wheel). For example, A / B in Example 1 indicates that the tread rubber of the front tire is A and the tread rubber of the rear tire is B. Similarly, in Table 2, the values of tan δ (F) / tan δ (R) at 30 ° C., 60 ° C. and 100 ° C. of the tread rubber of each tire of the front wheels and the rear wheels are represented by (tan δ
The value of Es (F) / Es (R) is also shown in the section of (Es ratio).

[0031]

[Table 2]

Tires of Examples 1 to 3 and Comparative Example 1
The tires from Nos. 1 to 7 were used as test tires, and the following evaluation tests were carried out using actual vehicles. The test method was as follows. Each test tire was installed in a standard rim 6JJ × 15, and the standard internal pressure was 2.2k.
After filling with gf / cm ² and mounting it on a test vehicle, it was evaluated by two experienced test drivers for feeling evaluation of circuit running in various running methods.

Table 3 shows the measurement results of the maximum temperature of the tread immediately after running and the scores of the test drivers. The score is 10
The score is perfect and the passing score is 7 or more. The temperature of the tread rubber at the start of the test was 25 ° C.

[0034]

[Table 3]

In Table 3, the height of the gripping force is represented as (grip feeling) in the table, and this is shown by (F) for the front tire and (R) for the rear tire. This grip feeling score is a total value from the start to the end of the test.
Also, the difference in grip force between the front and rear tires is expressed as grip balance. The larger the value, the better.

In Table 3, the sense of rigidity is the responsiveness of the vehicle during steering over the entire period from the beginning to the end of travel.
The change at the time of HOT represents the change in the feeling of rigidity when the vehicle runs from the beginning of running until the temperature of the tread rubber rises.

As is clear from the results of the evaluation test, the tires of the respective examples according to the present invention have excellent gripping force and rigidity in comparison with the tires of the comparative examples from the start of running to the front and rear tires. At the same time, it can be seen that the balance between the front and rear wheel tires is maintained at a high level while maintaining the grip and rigidity of the front and rear tires at a high level even during or immediately before the running when the temperature of the tread rubber has risen. .

[0038]

According to the present invention, the grip force of the front tires and the rear tires and the gripping force of the front tires and the rear tires under various running conditions on both wet and dry road surfaces under the temperature change of the tread rubber as well as the ambient temperature change. It is possible to achieve a high level of rigidity and to balance the grip and rigidity of these front and rear wheel tires appropriately, and to use it for vehicles such as sports cars or racing cars that require a higher degree of transient motion performance. It is possible to provide a pneumatic tire paired with front and rear wheels, which is suitable for.

Claims (1)

[Claims] 1. The tread rubber quality of a front tire is different from that of a rear tire when the vehicle is mounted, and the loss tangent and the storage elastic modulus of the tread rubber of the front tire are tan δ.
(F) and Es (F), the loss tangent and storage elastic modulus of the tread rubber of the rear tire are tan δ (R) and Es.
(R), the loss tangent and storage elastic modulus of these tread rubbers are 0.5 <tan δ (F) <tan δ (R) at 30 ° C .; 1.0 × 10 ⁸ dyn / cm ² < Es (F); 1.0 × 10 ⁸ dyn / cm ² <Es (R); and in the temperature range of 30 ° C. or higher and 100 ° C. or lower, 0.85 ≦ tanδ (F) / tanδ (R) ≦ 0.9
5; 0.9 ≤ Es (F) / Es (R) ≤ 1.1;