JPS6271707A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the steering stability and drive feeling and reduce noise by setting the relation between the longitudinal and the lateral rigity of the outside part of a tire positioned outside a vehicle and the relation between the longitudinal and lateral rigidity of the inside part of the tire inside the vehicle so as to satisfy the following equations. CONSTITUTION:The longitudinal rigidity KVO and the lateral rigidity KLO of the tire outside part positioned outside a vehicle and the longitudinal rigidity KVI and the lateral rigidity KLI of the tire inside part positioned inside the vehicle are set so as to satisfy the following equations. With such constitution, the drive feeling can be improved by reducing the deflection quantity of the tire, and the steering stability can be improved by improving the cornering force and the cornering power. Further, noise can be reduced by reducing the vibration in the vertical direction.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pneumatic tire that improves riding comfort and steering stability and reduces noise by changing the stiffness of the inner and outer parts of the tire. .

[Conventional technology]

Generally, when tires are mounted on a vehicle and the vehicle is driven, the load and deformation behavior are different between the inner side and the outer side of the vehicle around the tire equator. Particularly when the vehicle is cornering, the tire side portions on the outside of the vehicle, which are located outside the turning circle, receive a large load. As a result, compared to when the tire is running straight, as shown by the solid line in Figure 1, when turning, the tread contact surface of the tire is approximately trapezoidal with a longer contact area on the outside of the turning circle, as shown by the broken line. becomes. This imbalance in ground contact conditions not only causes uneven wear of the tread, but also impairs steering stability. To date, proposals have been made to make the tread patterns of tires located on the inside and outside of a vehicle asymmetrical, or to have a structure in which the stiffness of the tire bead differs on both sides.

However, these methods merely make both sides asymmetrical, and there is no consideration from a comprehensive perspective of ride comfort, handling stability, and low noise to determine how much the stiffness should be quantitatively adjusted. do not have.

[Problem to be solved]

The present invention improves riding comfort by setting the longitudinal and lateral stiffness characteristics of the tire side portions within a predetermined range on both sides of the tire.
The objective is to provide a pneumatic tire with excellent handling stability and low noise.

(Technical Means) An air system characterized in that the longitudinal stiffness KVO and lateral stiffness KLO of the outer part of the tire located on the outside of the vehicle and the longitudinal stiffness KVI and lateral stiffness KLI of the inner part of the tire located on the inside of the vehicle satisfy the following relationship. It is a built-in tire.

1.5≦KVO/KVT≦3.0 1.5≦K LO/K Ll≦3.0 An embodiment of the present invention will be described based on the drawings.

The lateral stiffness KLO1KLr of the outer part of the tire and the inner part of the tire means that the tire is assembled on a rim, for example, size 185/70SR.
14, the specified internal pressure is 2. After filling with OOkg/cj, the amount of lateral deflection δ■, δO is measured when a load of 400 kir is applied to each tire and the lateral force is changed, and the value is divided by the lateral load. .

On the other hand, the longitudinal stiffness of the outer part of the tire and the inner part of the tire is KVO1KV.
I means the tire is assembled on a rim, for example, size 185/70.
In the case of SR14, the specified internal pressure is 2. After filling with OOkg/c111, the amount of vertical deflection is measured when a load is applied in the radial direction of the tire, and the value is calculated by dividing the amount by the load.

Therefore, in the present invention, the ratio of the longitudinal stiffness and lateral stiffness of the outer tire part and the tire inner part K VO / K VL K LO / K
Set Ll to 1.5 or more and 3.0 or less.

Generally, the higher the cornering power and cornering force, the better the steering stability, and the higher the cornering force under high load, the better the cornering limit. The lateral acceleration generated when the vehicle corners causes the vehicle to turn, and the load on the tire sidewall located on the outside of the vehicle with respect to the turning center increases, while the load on the tire sidewall located on the inside of the vehicle decreases.

Therefore, the cornering limit depends on the rigidity of the tire sidewall located on the outside of the vehicle. Therefore, from the viewpoint of handling stability, it is necessary to make the lateral rigidity of the outer side of the tire higher than that of the inner side of the tire.

Next, regarding ride comfort, if the longitudinal stiffness of the outer part of the tire is KvO and the longitudinal stiffness of the inner part of the tire is KVI, then the total longitudinal stiffness is expressed as the sum of both. Accordingly *-KVI+KVO
(KVO>Kν■) Here, for example, if KVO-2KVI, then water-3KVI.Comparing this with a conventional tire in which both sides of the tire have the same longitudinal stiffness, the longitudinal stiffness of the conventional tire (2KVO) is 25% smaller. As a result, riding comfort improves.

Furthermore, in terms of low noise, that is, relatively high-frequency vibrations and muffled sounds in the vehicle interior in response to road surface input, both sides of the tire function as a vibration transmission system. Here, if the longitudinal stiffness 1 and the lateral stiffness of both sides of the tire are changed on the inside and outside, the natural circular frequency WO1 damping ratio CO expressed by the following equation will also have different values on both sides.

WO-k/m m: Mass C0=C/2 km k: Spring constant C: Damping coefficient Therefore, the frequency response during driving is more dispersed compared to conventional tires that have the same stiffness on both sides, resulting in lower peaks and lower noise. can be achieved.

In the tire having the cross-sectional structure shown in FIG. 3, various tires with different longitudinal and lateral rigidities were manufactured by changing the bead apex A and the bead reinforcing material B.

7.'' 7./ /゛/''7.' Table 1 The measurement results of the tire characteristics of each tire of Comparative Example 1, Comparative Example 3, and Example 1 are shown in FIGS. 4 to 7.

In the embodiment of the present invention, as shown in Fig. 4, the amount of tire deflection is small and ride comfort is improved, and as shown in Figs. S5 and 6, cornering force and cornering power are improved, so F! A: In addition to the improvement in longitudinal stability, it can be seen from Fig. 7 that the vertical vibration is smaller and the noise is reduced.

(Effects of the Invention) As described above, in the present invention, the longitudinal stiffness and lateral stiffness of the outer and inner parts of the tire are set within predetermined ranges, so that it is possible to improve riding comfort, driving stability, and reduce noise.

[Brief explanation of drawings]

Claims (1)

[Claims] (1) Longitudinal stiffness KVO of the outer part of the tire located on the outer side of the vehicle
, and a pneumatic tire characterized in that the lateral stiffness KLO, the longitudinal stiffness KVI and the lateral stiffness KLI of the inner side of the tire located on the inner side of the vehicle satisfy the following relationship. 1.5≦KVO/KVI≦3.0 1.5≦KLO/KLI≦3.0