JPS6390404A - Nonsymmetrical pattern of pneumatic radial tire of car - Google Patents

Abstract

PURPOSE:To improve drivability by providing crossing main grooves in three areas formed with two circumferential grooves on a tread, at the same interval for each of said areas and making a circumferential pitch and inclination angle in a specific relation between areas. CONSTITUTION:A tread T is divided into areas 1-3 by means of tread ends (e), (e) and circumferential main grooves 4, 5. And, crossing main grooves 6-9 are provided so as to be at the same interval in the circumferential direction for each of the areas 1-3, and relations P1>P2>P3, P1/P2=1.5-3, and P1/P3=2-4 are established among circumferential pitches P1-P3 in the respective areas. Also, the crossing main grooves 6-9 are inclined in the circumferential direction being directed from the area having a larger pitch to the area having a smaller pitch, with each inclination angle being set as, alpha1=15-40 deg., alpha2=30-60 deg., and alpha3=50-90 deg.. And, the contact with ground is made from the center area of tire at the time of rolling under a load. By this structure, the drivability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic radial tire pattern for passenger cars, and particularly to a novel pattern that improves handling stability.

(Prior Art) Generally, a tire pattern is a symmetrical pattern consisting of a rib pattern and a protrusion pattern. Some asymmetrical patterns can be seen, but in any case, they focused on either dry handling or wet handling, or they were a compromise between them.

(Problem to be Solved by the Invention) However, drivers generally purchase only one type of tire. - If you purchase a tire twice, it will remain the same tire until it is completely worn out. That is, in the case of a dry-oriented tire, wet performance must be sacrificed to some extent, and in the case of a wet-oriented tire, the opposite is true. Therefore, the present invention aims to provide a tread pattern that can easily ensure performance according to each person's preference depending on which of the various performances is prioritized.

(Means for Solving the Problems) As a result of various studies conducted by the inventors, they focused on arranging tread patterns with different characteristics on both sides of the tread.
In particular, it has been discovered that the block rigidity, that is, the pitch ratio in the circumferential direction can be changed, and specifically, this can be achieved as follows.

In an asymmetrical pattern of a pneumatic radial tire for a passenger car having at least two main grooves in the circumferential direction and defined by the main grooves into at least three regions, the transverse grooves crossing the main grooves are arranged in at least one section in each section. at least transverse main grooves opening at the tread ends and extending in the transverse direction are disposed in each section at substantially equal intervals circumferentially; the transverse main grooves in the three sections extend from one tread end to the other; This problem was solved by sequentially changing the circumferential pitch ratio of the transverse main grooves in each area.

(Function) The pattern is asymmetrical except for the center, the tread area is divided into at least three areas, each area is provided with a plurality of grooves extending at least in the transverse direction on the circumference, and the circumferential pitch ratio of the transverse main grooves is one side. The reason why the area changes sequentially from one area to the other is that the circumferential pitch ratio of the areas on both sides of the tread is set at both extremes. By setting the pitch ratio in the circumferential direction midway between both side areas, sudden changes in tread rigidity or characteristics are avoided, allowing for smooth changes. One way to use it is to install it so that the side with the larger circumferential pitch ratio faces the outside of the vehicle, and if you want performance in dry conditions to be important, and if you want performance in wet conditions, you can install it in the opposite direction. Furthermore, by changing the mounting method for the front and rear wheels, it is possible to adapt to various characteristics.

In order to ensure rigidity, it is preferable that the inclination angle of the transverse main groove with respect to the tire circumferential direction gradually increases from an area with a large circumferential pitch ratio to an area with a small circumferential pitch ratio, and each angle is 1.
5-40°, 30-60°, 50-9°.

A directional pattern is also preferred, ie, a pattern that contacts the ground sequentially from the transverse main groove in the center area of the tire tread toward the tread edges when the tire rolls under load.

(Example) Tire size: 205/80R15 FIG. 1 shows a developed view of a pattern of one example of the present invention, which is a tire having a general tire structure and reinforcement structure.

The tread T has tread ends e, e and a circumferential wide main groove 4 (
1,2,3. It is divided into sections, and each section has a transverse main groove 8, 7, 8, 9 . are arranged at substantially equal intervals in each area in the circumferential direction.The circumferential pitch P1 of the transverse main grooves B in the first area is 70 mm, and the inclination angle αl with respect to the tire circumferential direction is 20 degrees. Pitch P2.35 wet, α2, 42°, 3 area has pitch P3 of 17.5mm
, α3 is 82°. Moreover, narrow grooves 10 of grooves @21 mm are arranged on both sides of the wide main groove 4 in the circumferential direction.

Furthermore, although the transverse main grooves 8 and 7 in areas 1 and 2 are not open to the circumferentially wide main groove 4, it goes without saying that they may be opened, provided that at least 50% of the area is There needs to be a groove.

Next, an example of the mounting method will be described below.In this embodiment, it is preferable that the center area of the tire contacts the ground when the tire rolls under load, for reasons such as drainage properties.

Also, the radius X of the center part of this embodiment is 71 mm.

(1) Dry driving: Both the front and rear wheels are mounted so that one area faces outside the vehicle, A (2) Wet driving, opposite to dry driving, B (3) Wet driving: Front wheels have one area facing inside the vehicle, and the rear The wheels are generally installed so that area 1 is located on the outside of the vehicle, as shown in C. However, this can be changed if necessary.

(effect) Great performance, expressed as an index with conventional tires set as 100.

, the conventional E tire is center-unisymmetric with 1 area placed on both sides, and the other parts are substantially the same as the l area, and the F tire is center-unisymmetric with 2.3 areas placed on both sides, both of which are center-unisymmetric. It is a directional pattern that touches the ground when the load rolls from the area.

[Brief explanation of the drawing]

FIG. 1 is a partial circumferential plan view of the pneumatic radial tire of the present invention.

Claims (1)

[Claims] 1. In an asymmetrical pattern of a pneumatic radial tire for a passenger car, which has at least two main grooves in the circumferential direction and is defined by the main grooves into at least three areas, the tire crosses the main grooves. The transverse grooves are open at least at each tread end, and at least transverse main grooves extending in the transverse direction are arranged at substantially equal intervals on the circumference in each region, and the transverse main grooves in the three regions are located at one tread end. A pattern of a pneumatic radial tire for a passenger car, characterized in that the circumferential pitch ratio of the transverse main grooves in each section changes sequentially from one tread end to the other tread end. 2. In claim 1, the inclination angle of the transverse main groove with respect to the tire circumferential direction gradually increases from an area with a large circumferential pitch ratio to an area with a small circumferential pitch ratio on the circumference of the transverse main groove, preferably 15 to 15. 40°, 30~60°, 50~9
A pneumatic radial tire pattern for passenger cars characterized by a 0° range. 3. The pattern of a pneumatic radial tire for a passenger car according to claim 1, wherein the transverse main groove forms a directional pattern such that the tire contacts the ground sequentially from the center area during load rolling. 4. In claim 1, if the smaller circumferential pitch ratio of the transverse main groove is 1, then the ratio is 1.5 to 3, 2 to 4 in order.
A pneumatic radial tire pattern for passenger cars characterized by a range of .