JPS595603Y2 - Radial tires for passenger cars - Google Patents

Description

[Detailed Description of the Invention] In recent years in the automobile industry, there has been a demand for improving the running fuel efficiency of vehicles from the viewpoints of energy conservation and economy.

One of the reasons for this is to lower the rolling resistance of the tire.

The rolling resistance of a tire is mainly caused by energy loss caused by movement of the tread and other structural materials such as the sidewall, playing force, and bead parts due to rolling.

However, it is known that radial tires for passenger cars, which use an organic fiber material for the case and a steel material for the belt, have lower rolling resistance than so-called bias tires.

The present invention relates to a radial tire for a passenger car in which the rolling resistance of the radial tire for a passenger car is further reduced.

The present invention will be explained below. EPA in the United States (En
vronmentalProtectionAge
(7) Vehicle fuel consumption tests are conducted on a chassis dynamo.

The present inventor completed the present invention as a result of intensive research to reduce the rolling resistance of tires on this chassis dynamo.

That is, it was found that the proportion of the tread portion involved in rolling resistance was approximately 50%, of which deformation due to compression accounted for approximately 40% and deformation due to bending accounted for approximately 10%.

Through this analysis, it has become possible to take effective measures to reduce the rolling resistance of tires.

Since the contribution of the tread portion is large, the aim of the present invention is to significantly reduce rolling resistance mainly through the viscoelastic properties of the tread rubber.

As for the viscoelastic properties of the rubber of the tread, it is preferable that the rubber has a small energy loss due to compressive deformation, and also has a small energy loss due to bending deformation.

If the compressive deformation of rubber is a constant stress behavior, the energy loss due to it is loss compliance E”/(E”)2
If the bending deformation is a constant strain behavior, the resulting energy loss is considered to be proportional to the loss modulus E''.

Therefore, in order to lower the rolling resistance from the dynamic characteristics of rubber, it is desirable to first lower the loss compliance and, in addition, lower the loss modulus.

From this, by increasing the complex modulus of elasticity E and lowering the loss modulus E, both the rolling resistance due to compressive deformation and the rolling resistance due to bending deformation can be decreased to a certain extent.

More preferably, when lowering the loss conformance and loss elasticity, the weighting is about 40:10 as described above (emphasis is placed on countermeasures for E''/(E)'' rather than E'').

Furthermore, it was found that this effect was greater in the center of the tread.

Therefore, in the present invention, the rolling resistance is significantly lowered by the following steps (see Figures 1 and 2).

That is, for a sample whose tread is made of one or more types of rubber and has a width TW1 that is 55% of the tread width TW at the center and has a shape of 30 mm in length, 4 mm in width, and 1.5 mm in thickness, the temperature is 70 mm. 70 kg/cm'<E'< 120 kg/cm when measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of °C, frequency of 10 Hz, amplitude of 2%, and initial strain of 10%.
cm" and 2kg/m<E"<13kg/am' and 0.3X10-3crrf/kg<E"/ (E US) 2
<2.3X10-3cxr'/kg Rubber 1, which has dynamic characteristics, accounts for 80% or more of the tire weight.

In addition, on both sides of the center part of the tread, there is a different type of rubber 2 different from the center part, for example, E = 60 kg/cm", E" =
15 kg/am" can be used to compensate for unsatisfactory performance in the center, such as wet skid performance.

With the present invention as described above, the rolling resistance of the tire can be lowered for the reasons mentioned above.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a tire for explaining an example of the radial tire of the present invention, and FIGS. 2 a to 2 d are tread portions for explaining examples of the tread portion of the radial tire of the present invention shown in FIG. A cross-sectional view of each is shown. TW... Tread width, TW1... Width of 55% of the tread width, A... Torets F, B...
...Belt, C...Case, 1...
・The rubber material specified in the scope of the utility model registration claim of this invention,
2...A different type of rubber from 1.

Claims (1)

[Claims for Utility Model Registration] The case has an organic fiber material cord layer, and the belt has at least one cord layer.
A radial tire for a passenger car with one or more metal cord layers, the tread of which is made of one or more types of rubber, has a dynamic characteristic of 70 kg/cm2 in a width range of 55% of the tread width in the central part. <E rice〈120kg/cm" and 2 kg/crn2<E"<13 kg
/cttt" and 0.3X 10-3cm2/kg<
E''/ (E')2< 2.3X10-3crrf/
kg where E" is the complex modulus of elasticity, E" is the loss modulus, and E"/(E)2 is the loss compliance. A radial tire for a passenger car that contains 80% or more of rubber by weight.