JPH026204A - Pneumatic tire for passenger car - Google Patents

Abstract

PURPOSE:To reduce noise at the time of steering operation of passenger tire having a tread pattern in an herringbone pattern so as to improve its dry control stability by specifying the bending position of each auxiliary groove and the angle thereof and the setting direction with respect to the car. CONSTITUTION:Auxiliary grooves 2 bent at right and left shoulder parts of a tire according to the present invention are arranged such that angles theta1, theta2, theta3 are respectively set within 0-90 deg. from the center area of tire to the bent point (lime C-C) and it is bent at an angle thetar of 90-135 deg. with respect to the tire peripheral direction at the bent point. The bent point (line C-C) of both the shoulder parts of the auxiliary groove are set at the position corresponding to 75-95% of the length (distance) B of the contacting width A against the ground so that it is in a protruding form seeing from the advance direction of car. It is thus possible to reduce noise at the time of steering operation of tire without deterioration in the wet skid performance.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a unidirectional tread pattern (hereinafter referred to as a unidirectional pattern) that has excellent wet skid performance and reduces noise during steering. This invention relates to pneumatic tires for passenger cars.

[Conventional technology]

Conventionally, as shown in Fig. 2, tires with excellent wet skid performance such as tire drainage performance have been developed with multiple main grooves 1.
When the tire is mounted on a vehicle, it has a sub-groove 2 having a bending point (line c-c position) or a bent part in the center area of the tire and a part of the shoulder of the tire (W indicates the width of contact with the ground), respectively. A tire is known which has a so-called herringbone-like unidirectional pattern in which the bending point C of the center region of the sub-groove 2 forms a V-shape in the direction of travel of the vehicle.

However, tires having such a herringbone-like unidirectional pattern have a problem in that the noise is significantly louder when the vehicle is steered than when the vehicle is moving straight. That is, in FIG. 2, the shaded area shows the shape of the tire contact area when the tire is mounted on a vehicle and the steering wheel is turned to the right (the contact area is seen through from inside the tire), and the steering wheel. When the vehicle is steered to the right by operation, the intersecting angle between the minor groove 2 in a part of the left shoulder on the outside of the turn where the load increases and the trailing edge line Lx of the tire's contact area (L+ is the leading edge line) is 000. (P part).

On the other hand, when turning, a lateral force is generated as shown by the arrow, and this lateral force distorts the shoulder block. When this distorted shoulder block is released from the ground surface, the intersection angle is close to 00 at the P part, so the entire block is released instantly, so there is a large gap between the block and the road surface. This causes the vehicle to slip, and the noise is significantly louder than when the vehicle is traveling straight.

[Problem to be solved by the invention]

An object of the present invention is to provide a tire for a passenger car that reduces noise generation during steering without impairing the excellent wet skid performance of the tire for a passenger car having a unidirectional pattern in the form of a herringbone pattern. It is.

[Means to solve the problem]

The tire of the present invention is characterized by consisting of a plurality of main grooves extending in the circumferential direction of the tire and a plurality of sub-grooves that cross the main grooves, and that these sub-grooves satisfy the following requirements (1) and (2). Features.

■ From a part of the tire center to a bending point of a part of both left and right shoulders, the angle with respect to the tire circumferential direction is set within the range of 0 to 90°, and at the bending point, the angle with respect to the tire circumferential direction is set within the range of 90 to 135°. It is bent at an angle, and the bending point is 75% to 95χ of the tire's [contact width x 172] (hereinafter referred to as half contact width) from the tire circumferential center line EE'.
(1) be installed on the vehicle so that the bending point of the sub-groove is convex when viewed from the direction of travel of the vehicle;

In the present invention, the above-mentioned ground contact width refers to a value determined for a tire with an air pressure corresponding to the designed regular load specified by JATMA and a load of 85X of the designed regular load.

FIG. 1 shows an example of the tread pattern of a passenger car tire according to the present invention, which is composed of a plurality of main grooves 1 and a plurality of sub-grooves 2 that cross the main grooves. , both the left and right shoulders are partially bent (the white arrows indicate the direction of tire travel).

In the tire of the present invention, it is important that the position and bending angle of the bending point (line C-C) of the sub-groove 2, which bends at a portion of both the left and right shoulders, and its bending angle are not arbitrary, but are at a specific position and angle. be.

First, the sub-groove 2, which is bent at a portion of both the left and right shoulders of the tire of the present invention, extends from the tire center area to the bending point (line c-c
) up to the angle θ8. θ2. θ3
are respectively set within the range of 0 to 90°,
906~ in the tire circumferential direction at the bending point (bending position)
It is necessary that it be bent at an angle θ7 of 1356 degrees.

That is, if the bending angle θ7 of this sub-groove exceeds 135°, the amount of rolling is not large, but the dry steering stability deteriorates, while if the bending angle θ7 is less than 90°, the dry steering stability is good. However, the amount of rolling is large (which is not desirable).

Then, a bending point of a part of both shoulders of the minor groove <line c-c>
must be provided at a position corresponding to a length (distance) B of 75 to 95χ of the tire half-contact width A from the tire circumferential center line EE'. That is, the bending point (line c-c) of this minor groove is aligned with the tire circumferential center line E-E'
If it is provided at a position corresponding to less than 75% of the tire's half-contact width A, the amount of rolling will be small, but the wet skid performance will deteriorate; c)
If it is provided at a position corresponding to a length exceeding 95χ of the half-contact width A, the wet skid property will be good, but the amount of rolling will increase, which is not preferable.

That is, FIG. 3 shows the shape of the tire contact surface (shaded area) when the tire of the present invention corresponding to FIG. 2 is mounted on a vehicle and the steering wheel is turned to the right (the contact surface is (see through). From this figure, it can be seen that in the case of the tire of the present invention, when the tire is steered to the right, as in the conventional tire shown in Fig. 2, the minor groove 2 of the shoulder part and the trailing edge line L2 of the ground contact area are formed. Since the intersection angle never becomes 0'' at once (P'' part, the noise caused by slipping with the road surface or when turning the steering wheel does not increase significantly compared to when driving straight.

FIG. 3 shows that the tire of the present invention, which has a herringbone trend pattern, is mounted so that the bending points (line C-c) of both shoulders are convex when viewed from the direction of travel of the vehicle. It also shows that this is necessary.

In the present invention, the shape of the main groove, the groove width and depth of the main groove and the sub-groove are not particularly limited, but the shape of the main groove is preferably linear from the viewpoint of the characteristics of the wafer 1. The width of the main groove is 6 to 12 mm, the depth is 5 to 9 mm, and the width of the minor groove is 2 to 12 mm.
6 mm, and the depth is preferably 5 to 9 mm.

〔Example〕

EXAMPLES Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

The tire performance was evaluated by the wet skid performance index, pre-steering feel, and dry steering stability feeling tests described below.

Wet skid performance index: A circular turning test with a turning radius of 100 m was conducted on a wet road surface with a water depth of 5 mm, and the maximum lateral acceleration was compared and evaluated.

Feeling before steering: The vehicle turned left and right (steering) on a circle with a radius of 30 mm on a dry road surface at a running speed of 40 km/hour, and the feeling before turning was evaluated.

Dry handling stability feeling: Air pressure 2.20Kgf/cm”, load 31400Kg
An actual vehicle driving test was conducted under the following conditions at a speed of 60 Km/hour to 120 Km/hour, and the feeling was evaluated.

Example It has the trend pattern shown in Figure 1, θ,.

θ2 and θ are each 45″, θ7 is 1200, and the length of the minor groove from the tire center to the bending point is 65L, 75χ, and 90χ, which is the tire half-contact width A.

Six types of tires (size 195/65R15) of 95χ, 100χ, and 110χ were created, and their wet skid performance index and feeling before steering were evaluated. FIG. 4 is a diagram plotting the wet skid performance of the tire and the noise characteristics during steering (feeling before steering) with respect to the set position of the bending point C of the sub-groove. From the figure, by providing the bending point of the minor groove at a length B of 75 to 95χ of the tire half-contact width A from the tire circumferential center line EE', it is possible to maintain good wet skid performance and roll. It can be seen that the front of the rudder can be reduced.

Moreover, it has a tread pattern shown in FIG. 1, and has a tread pattern of θ0. θ
2 and θ3 are each 45 degrees, the length B of the minor groove from the tire circumferential center line EE' to the bending point is 90% of the tire half-contact width A, and θ7 is 70' and 90 degrees.
, 120°, 135°, and 150° (size 195/65R15) were prepared, and their dry steering stability feeling and pre-steering feeling were evaluated.

FIG. 5 is a diagram plotting the relationship between the eight bending angles at the bending points of the secondary grooves, the feeling before steering, and the feeling of dry steering stability.

From the figure, the bending angle θ7 at the bending point of the sub groove 2 is 90″~
It can be seen that by setting the angle within the range of 135', it is possible to maintain good dry steering stability and reduce the amount before turning.

〔Effect of the invention〕

According to the present invention, in a passenger car tire having a herringbone tread pattern, by specifying the bending position and angle of the sub-groove, and the mounting direction on a vehicle, the tire having the herringbone pattern can be improved. It is possible to reduce noise during steering of this tire and improve dry steering stability without compromising wet skid performance, and together with the distinctive design of the herringbone pattern, the product value can be significantly increased. can.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of the tread pattern of the tire of the present invention, and FIGS. 2 and 3 show the relationship between the tread pattern and the shape of the steering landing surface of the conventional tire and the tire of the present invention, respectively. Fig. 4 is a diagram showing the relationship between the installation position of the bending point of the sub-groove, wet skid performance of the tire, and noise characteristics during steering, and Fig. 5 is a diagram showing the relationship between the installation position of the bending point of the sub-groove and the noise characteristics during steering, and Fig. 5 shows the bending angle θ at the bending point of the sub-groove. FIG. 3 is a diagram showing the relationship between the amount of rolling and the feeling of the amount of rolling and the feeling of dry steering stability. 1...Leading, 2...Minor groove, c-c...Bending point, θ
,. θ2. θ3.0 teeth...bending angle of the minor groove.

Claims (1)

[Scope of Claims] Consists of a plurality of main grooves extending in the tire circumferential direction and a plurality of sub-grooves that cross the main grooves, and these sub-grooves satisfy the following requirements (1) and (2). A pneumatic tire for passenger cars featuring: (1) The tire center part to the bending points of both left and right shoulder parts are arranged at an angle of 0 to 90 degrees with respect to the tire circumferential direction, and the bending points are arranged at an angle of 90 to 90 degrees with respect to the tire circumferential direction.
It is bent at an angle of 135 degrees, and the bending point is 75 degrees from the tire circumferential center line to the tire's [ground contact width x 1/2].
% to 95% of the length; and (2) be mounted on the vehicle so that the bending point of the minor groove has a convex shape when viewed from the direction of travel of the vehicle.