JPH0649441Y2 - Low noise tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a low-noise tire that can reduce noise during traveling without impairing traction and can be suitably used as a tire for passenger cars.

[Conventional technology]

Generally, in order to increase the traction force in a tire, as shown in FIG. 1, a rib formed by a longitudinal groove extending in the tire circumferential direction is divided by a lateral groove a extending in the tire axial direction, and the tread is parallel to the tire equatorial plane X. It is widely adopted that the block pattern b is composed of rows of blocks b arranged in the tire circumferential direction.

[Problems to be solved by the device]

However, when a tire having such a block pattern travels at a high speed on a paved road surface, the blocks b are intermittently grounded for each block arranged in the tire circumferential direction, and a discontinuous impact sound is generated at a tread edge at the time of grounding. Is causing noise.

In addition to such impact noise, the air inside the groove surrounding the block is compressed along with the deformation of the block at the time of grounding,
When this expands, a compressional wave is generated, which becomes a pumping sound, and noise is easily generated.

Further, in the tire having such a block pattern, in order to further improve the traction force, as shown in FIG.
It is preferable to increase the rigidity of the block by increasing the length of the block in the tire axial direction, rather than by making the length of the block in the axial direction of the tire small, such as 6 rows provided with vertical main grooves. .

However, in such a horizontally long block having a large rigidity, the impact sound of the block b hitting the ground is further increased, and the length of the groove sandwiched by the block is increased, so that a pumping sound based on the compression wave of the air is also generated. Increase.

The present invention has been completed as a result of various studies on blocks in the tread portion, and an object thereof is to provide a low-noise tire capable of reducing noise without impairing traction force.

[Means for Solving the Problems]

In the present invention, the tread has a block pattern in which blocks are arranged in the tire circumferential direction, and 1 to 3 vertical main grooves having a groove width of 7 to 15 mm extending in the tire circumferential direction and lateral grooves intersecting with the vertical main grooves. In the block divided by, each of the lateral grooves that sandwich the block opens on the same straight line in the tire circumferential direction and has a groove width of 1 to 1 that is interrupted at the connecting portion.
A low noise tire in which a linear vertical groove of 4 mm is formed and the circumferential length of the connecting portion is 30% or less of the circumferential length of the block.

[Action]

In this way, the number of vertical main grooves extending in the tire circumferential direction and having a groove width of 7 to 15 mm is set to 1 to 3, and the length of the block in the tire axial direction is increased to improve the traction. Also, by providing vertical narrow grooves that open in both lateral grooves that sandwich this block and extend in the tire circumferential direction, the rigidity of the block is alleviated, the impact at the stepped edge of the block is alleviated, and the air escape is increased to some extent to create a pumping noise. It is possible to suppress the impact sound and reduce the noise. Furthermore, by providing vertical narrow grooves on the same straight line in the tire circumferential direction,
The length of the connecting portion between the vertical narrow grooves is reduced, and while increasing the effect of mitigating the block rigidity as 30% or less of the circumferential length of the block, preventing excessive reduction in tread rigidity by having the connecting portion, Particularly, it can be suitably used as a passenger car tire.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 2 and 3 show an embodiment of the present invention. In the drawings, a tire 1 has 1 to 3 treads, in this embodiment, two longitudinal main grooves L1 and L2 extending in the tire circumferential direction and lateral grooves. By providing G ...., a block group P1 made up of blocks A arranged in the tire circumferential direction on the tire equatorial plane X, and vertical main grooves L1 on both sides of the block group P1 in the ground contact portion CR of the tread portion. A block group P2, P3 of shoulders made up of blocks B, C arranged along the shoulder edge in the tire circumferential direction with L2 interposed therebetween.
And are formed.

Each block A, B, C is divided in the tire circumferential direction by the lateral groove G, and each block A, B, C extends on the same straight line in the tire circumferential direction and sandwiches these blocks A to C. A linear vertical narrow groove 2 that opens in the lateral groove G is provided. The vertical narrow groove 2 is interrupted in the blocks A to C to form a connecting portion. Further, in the present embodiment, the vertical narrow groove 2 is provided in the central portion of both wall surfaces of the blocks A to C facing the horizontal groove G, and opens in the horizontal groove G, respectively.

In the present specification, the ground contact portion CR of the tread portion refers to an area having a width centered on the tire equatorial plane and the tire tread surface actually touches the road surface under normal running conditions.

The vertical main grooves L1 and L2 extend in the tire circumferential direction and are preferably linear grooves, and the groove width WL is 7 mm or more. This vertical main groove contributes to drainage on a wet road surface, and if the groove width WL is less than 7 mm, its effect is not sufficient. On the other hand, if the groove width is made too large, the block width inevitably decreases, which is not preferable from the viewpoint of wear resistance and traction, and in the case of tires for passenger cars, it is usually set to 15 mm or less.

Further, one to three vertical main grooves can be provided as described above, for example, one vertical main groove is arranged on the equatorial plane of the tire or two vertical main grooves are arranged on both sides thereof.

By setting the number of the vertical main grooves L1 and L2 to be a small number of 1 to 3 and setting the groove width WL to be in the above range, the tire axial lengths of the blocks A to C of the ground contact portion CR can be reduced to the conventional values. It is possible to increase the width compared to that of the block pattern, and it can be made horizontally long with excellent traction. When the number of the vertical main grooves is four or more, the block axial rigidity is reduced by reducing the axial length of the block, that is, the width.

Further, the lateral grooves G ... As shown in FIGS. 2 and 3, each of the blocks A, B, and C has a shorter tire circumference than the length of each block in the tire axial direction so that the blocks A, B, and C are laterally long rectangular bodies. The tires are arranged in the tire circumferential direction with a pitch of the length in the direction.

Further, the lateral groove G can extend in the tire axial direction or can be formed to be inclined in the tire axial direction.

The vertical narrow grooves 2 extend linearly in the tire circumferential direction, and the groove width W2 is set in the range of 1 to 4 mm. The arrangement of the vertical narrow grooves 2 can reduce the rigidity of the blocks A, B, C, reduce the impact transmitted from the tread to each part of the tire at the time of grounding, and suppress the impact sound. Groove width
If W2 is less than 1 mm, this effect is small, while if it exceeds 4 mm, the rigidity of the block becomes too small, which is not desirable in terms of wear resistance.

Further, by making the vertical narrow groove 2 linear and extending in the tire circumferential direction, it is possible to easily release the compressed and expanded air in the groove due to the tread deformation at the time of contact with the ground, and reduce the occurrence of compression waves of air. Therefore, the pumping sound can be suppressed.

Further, the vertical narrow groove 2 is interrupted in the blocks A, B, and C, and its length is set to the tire circumferential direction length of the blocks A to C.
By having a connection portion of 30% or less and partially separating blocks A to C, transmission of vibrations and the like can be blocked and vibration noise can be reduced without excessively reducing the rigidity of the blocks. As shown in the enlarged view of the block A in FIG. 3, the traction can be maintained, for example, by leaving the connecting portion at the center of the block in the tire circumferential direction.

The length m of the connecting portion is 30% of the circumferential length M of the block.
It is preferably 10% or less. As mentioned above,
Since the connecting portion does not excessively reduce the block rigidity, it is set to a length that does not easily break.

As described above, the vertical narrow groove 2 separates the blocks A, B, and C at the central portion in the tire axial direction with a uniform length, that is, a1 =
It is preferred that a2, b1 = b2, c1 = c2, but different lengths can be used, namely a1 ≠ a2, b1 ≠ b2, c1 ≠ c2.
Further, according to the purpose, specifications such as the number, the arrangement, and the depth can be selected.

Further, the blocks A, B, and C may be trapezoidal, parallelogrammic, or the like, depending on the inclination of the lateral grooves, in addition to the rectangular plane.

Specific example In Fig. 2, the tire size is determined by removing the connecting part and using a tread pattern in which the blocks are separated by vertical grooves
A 205 / 60R15 passenger car tire with a modified vertical narrow groove 2 having a different groove width was prototyped at a speed of 40 to 80 km / h and an internal pressure of 2.0 kg / c.
Under a driving condition of m ² and a load of 515 kg, put the sound collecting microphone right next to the tire, 100 cm from the center of the tire width, and 25 cm from the ground contact surface.
Was measured in an anechoic chamber at the height of (in accordance with the tire noise test method specified in JIS OC606). The length m of the connecting part is 30%
It has been found that there is no great difference in the noise characteristics when:

The result of the noise test is shown in FIG.

The detailed specifications of the example products are as follows.

From FIG. 4, it is recognized that the noise level in the range of 1 to 4 mm of the vertical fine grooves is lower than that of the vertical fine grooves of 0 mm, that is, the one without the vertical fine grooves. Furthermore, there is no difference in traction in this range.

[Effects of the Invention] As described above, the impact noise and the pumping noise can be reduced and the noise can be reduced in the tire having a block pattern on the basis that the horizontally long blocks are partially separated by the vertical grooves in the tire circumferential direction. Further, since the blocks are separated only partially, it is possible to prevent the rigidity of the block from being excessively lowered and to maintain the traction force.

[Brief description of drawings]

FIG. 1 is a partial plan view showing a tread portion of a conventional tire,
FIG. 2 is a partial plan view showing an embodiment of the present invention, FIG. 3 is a partially enlarged view of a block, and FIG. 4 is a graph showing the relationship between the noise level and the groove width of the vertical narrow groove. A, B, C ... Block, G ... Horizontal groove, L1, L2 ... Vertical main groove, 2 ... Vertical narrow groove, CR ... Grounding part, P1, P2, P3 ... Block group.

Claims (1)

[Scope of utility model registration request] 1. A tread having a block pattern in which blocks are arranged in a tire circumferential direction, and 1 to 3 vertical main grooves having a groove width of 7 to 15 mm extending in the tire circumferential direction and lateral grooves intersecting with the vertical main grooves. Each of the blocks divided by and has a groove width of 1 which is opened at each of the lateral grooves sandwiching the block and extends on the same straight line in the tire circumferential direction and is interrupted at the connecting portion.
A low noise tire in which a straight vertical groove of up to 4 mm is formed and the circumferential length of the connecting portion is 30% or less of the circumferential length of the block.