JPH0740714A - Pneumatic tire for passenger car - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire for passenger car which can reduce the PRCF and the handle flowing amount without deteriorating the intrinsic characteristics of a herical pattern, even though the try pattern is made in a herical pattern. CONSTITUTION:While sipings which combine from two obtuse angle points P and P' of a lozenge-shaped block to two points Q and Q' separated 0.20<=d/D<0.50 and 0.20<=d'/D<0.50 to the block width D along the sides at an auxiliary groove side of the lozenge-shaped block, are provided to the lozenge-shaped block of a herical pattern, the angle of the sipings to the peripheral direction of a tire is made 5 deg. or more, in this pneumatic tire for passenger car.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for passenger cars having a so-called helical pattern of block patterns, and more particularly to a pneumatic tire for passenger cars in which the handle flow of the vehicle, which is a drawback of the helical patterns, is improved. Containing tires.

[0002]

2. Description of the Related Art Among tread patterns provided in pneumatic tires for passenger cars, a block pattern has better drainage and a better wet performance than a rib pattern. However, on the other hand, there is a drawback that the pattern noise is larger than that of the rib pattern. In order to reduce the pattern noise of such a block pattern while ensuring the wet performance, the so-called sub-grooves are inclined in the same direction with respect to the plurality of main grooves extending in the tire circumferential direction. A helical pattern has been proposed.

In this helical pattern, the block shape is a rhombus and the rigidity of the front and rear ends is small, so the impact force of the road surface reaction force component in the tire lateral direction when the block steps on the road surface becomes weak. , The impact noise can be reduced. However, this diamond-shaped block has a greater rigidity on the obtuse angle side than the acute angle side of the left and right ends, and is uneven on the left and right, so when the road is stepped on, the road surface reaction force component of the tire lateral component increases, As a result, cornering force (hereinafter PRCF)
There is a drawback that the steering wheel flow that hinders the straight running of the vehicle is generated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make a tread pattern a so-called helical pattern, but to reduce the PRCF and the steering wheel flow rate without deteriorating the original characteristics of the helical pattern. The object is to provide a pneumatic tire for use, especially a radial tire.

[0005]

A pneumatic tire for passenger cars according to the present invention that achieves the above object comprises a plurality of main grooves extending in the tire circumferential direction on a tread surface and a plurality of parallel main grooves. In a pneumatic tire in which sub-grooves to be arranged are diagonally intersected to form a block pattern composed of a large number of rhombic blocks, two obtuse angle points of the rhombic blocks are provided in the rhombic blocks arranged at least in the ground contact center area of the tread surface. 0.20 ≦ d / with respect to the block width D from P and P ′ along the sub-groove side of the diamond-shaped block.
D <0.50 and 0.20 ≦ d ′ / D <0.50
It is characterized in that a sipe that connects two points Q and Q ′ apart from each other is provided and the angle of the sipe with respect to the tire circumferential direction is 5 ° or more.

By providing the sipe having the above-described structure in the rhombus block, the rigidity on the acute side and the obtuse angle side are made substantially the same, so that the tire lateral force of the road surface reaction force when the rhombus block steps on the road surface. It is possible to reduce the direction component and reduce the handle flow amount. Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

FIG. 1 shows an example of a tread pattern provided in the pneumatic tire of the present invention. Within the tread contact width W of the tread surface 1, a plurality of main grooves 2 are arranged in the tire circumferential direction.
Are provided, and a large number of sub-grooves 3 are spirally provided so as to intersect the main grooves 2 obliquely, and a large number of rhombus blocks 4 are provided.
Is formed. Among these, in the diamond-shaped block 4 forming the two block rows located in the center, sipe 5 inclined in the direction opposite to the sub-groove 3 is provided so as to divide into two.

As shown in FIG. 2, the sipe 5 is separated from the two obtuse angle points P and P'of the rhombic block along the sides of the sub groove 3 by a distance d and d'in the tire width direction. It is formed so as to connect two points Q and Q '. This distance d,
d ′ is 0.20 ≦ d / with respect to the block width D, respectively.
It is installed in the region of D <0.50 and 0.20 ≦ d ′ / D <0.50, and the sipe 5 has an inclination angle θ with respect to the tire circumferential direction of 5 ° or more.

By setting the end portions Q and Q'of the sipe 5 within the above-mentioned d / D and d '/ D range as described above, the rigidity is higher than the acute angle side with respect to the center of the block width, respectively. Since the obtuse angle points P and P'are offset, the rigidity of the left and right end portions of the rhombus block 5 is substantially balanced between the obtuse angle side and the acute angle side. Therefore, this diamond-shaped block 5
Reduces the lateral component of the road reaction force when the vehicle steps on the road surface. Further, the sipes 5 act so as to cancel out the road surface reaction forces in the tire width direction due to the edges of the auxiliary grooves 3 with respect to the tire circumferential direction. Therefore, by summing up these actions, the PRCF as a whole is
To lower the flow and prevent steering wheel flow.

The helical pattern is designed to reduce the pattern noise of the block pattern. Since the sipe 5 reduces the rigidity of the rhombus block 4, the pattern noise reducing effect is further improved. D / D, d'defining the ends Q, Q'of the sipe 5
When / D is 0.50 or more, the rigidity difference between the acute angle side and the obtuse angle side is further increased as compared with the case where no sipe is provided, so that PRCF is increased rather. If the d / D and d '/ D are less than 0.20, uneven wear of the heel and toe is likely to occur in the diamond block. Further, if the inclination angle θ of the sipe 5 with respect to the tire circumferential direction is smaller than 5 °, the PRCF reduction effect cannot be expected.

In the present invention, the sipes 5 may be provided on all the rhombic blocks 4 on the tread surface, but the object of the present invention can be achieved if they are provided on at least the rhombic blocks 4 in the central region. . More preferably, it should be provided in the central region corresponding to at least 1/3 width of the tread ground contact width W. The reason for this is that the inventors of the present invention have experimentally investigated the contribution rate of each block row to the PRCF using a helical pattern in which six block rows are arranged in the tread ground contact width W, and the central two rows are shown. The block row alone occupies almost 62% of the total, and the remaining 38
The reason is that the two columns on both sides occupy the percentage only. From this, the object of the present invention can be achieved if the sipes are provided at least in the rhombic blocks of the block row in the central region, and according to the above-mentioned rules.

[0012]

Example: Tire size is 205 / 65R15 93
H, except that a tipe pattern is provided with a sipe, except that the helical pattern shown in FIG. 1 is used, and the d / D of the sipe provided in the diamond-shaped blocks in the central two-row block row,
The tires of Examples 1 to 3 in which d ′ / D and the inclination angle θ were different as shown in Table 1, the tires of Comparative Examples 1 to 10, and the tire of the conventional example in which no sipes were provided were manufactured. did.

In these tires, the block shapes of the rhombic blocks provided with sipes are shown in Table 1 for reference. Further, the range of the sipe inclination angle θ indicates the range in which the blocks are arranged in the tire circumferential direction due to the variable pitch. For these 14 types of tires,
Each of them was mounted on a rim with a rim size of 6 × 15 JJ and was filled with air pressure of 2.0 kg / cm ^2, and PRCF, handle flow rate, pattern noise and uneven wear were measured by the following measuring methods, and the measurement results are shown in Table 1. It was

PRCF: Residual cornering force (PRCF) of the plysteer component when a load of 500 kgf is applied to the test tire by an MTS cornering tester.
Was measured. The measurement results are shown by an index with the tire of Conventional Example being 100. The smaller the index, the better.

Steering wheel flow rate: A test tire was mounted on a passenger car with a displacement of 3000 cc, and the running speed was 100 km / h.
While traveling straight ahead, the distance (m) that the vehicle flowed in the lateral direction was measured when the hand was released from the steering wheel in a measurement section of 100 m. Pattern noise: A test tire was mounted on a passenger car with a displacement of 3000 cc, and five inspectors evaluated the pattern noise of the test vehicle at a speed of 60 km / h. The evaluation results are shown by an index with the average value of the evaluation values of 5 inspectors being 100 as the value of the tire of the conventional example. The larger the index, the better.

Uneven wear resistance: A test tire was attached to a passenger car with a displacement of 3000 cc, and the average value of heel and toe wear amount of each block was measured for the two central block rows after traveling 30,000 km on a general road. It was measured. The reciprocal of the measured value is used as the measurement result, and the reciprocal value of the conventional tire is 1
It is shown by an index of 00. A larger index means less uneven wear.

[0017] From Table 1, d / D and d'of the sipe provided in the diamond block
Example tires 1 to 3 in which the conditions of / d, θ are within the specified range of the present invention are superior to the conventional example tire in any of PRCF, steering wheel flow rate, and pattern noise, and uneven wear is almost equal to the conventional example tire. You can see that it can be maintained like a tire.

[0018]

As described above, in the pneumatic tire for passenger cars of the present invention, the two obtuse angle points P of the rhombus blocks are provided in the rhombus blocks arranged at least in the ground contact center area of the block pattern composed of a large number of rhombus blocks. Block width D along the sub-groove side of the rhombic block from P '
, 0.20 ≦ d / D <0.50, and 0.
Two points Q, Q'that are separated by 20≤d '/ D <0.50
Since the sipe that connects the sipe is provided and the angle of the sipe with respect to the tire circumferential direction is set to 5 ° or more, a large PRCF peculiar to the helical pattern can be reduced and steering wheel flow can be prevented. Moreover, the pattern noise can be further reduced by providing the sipes.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a tread pattern of a pneumatic tire for passenger cars of the present invention.

FIG. 2 is an enlarged view of a rhombus block provided in the tire of the present invention.

[Explanation of symbols]

 1 Tread surface 2 Main groove 3 Sub groove 4 Rhombic block 5 Sipe

Claims (1)

[Claims] 1. A block pattern composed of a large number of diamond-shaped blocks is formed by obliquely intersecting a plurality of main grooves extending in the tire circumferential direction on a tread surface with a plurality of sub-grooves arranged in parallel to the main grooves. In the formed pneumatic tire,
In the rhombic block arranged at least in the ground contact center area of the tread surface, 0 from the two obtuse angle points P and P ′ of the rhombic block along the sub groove side of the rhombic block with respect to the block width D, 0 .20 ≦ d / D <0.50 and a sipe that connects two points Q and Q ′ separated by 0.20 ≦ d ′ / D <0.50, and the angle of the sipe with respect to the tire circumferential direction Pneumatic tires for passenger cars with an angle of 5 ° or more.