JPH0453722B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a low-noise tire with a block pattern that reduces the noise generated when the tire contacts the road surface during running and can be used for motorcycles, passenger cars, trucks, buses, etc. . [Prior Art] Conventionally, in order to improve the traction and braking performance of tires, tires with a block pattern having a block row consisting of blocks arranged in the circumferential direction of the tire have been used for motorcycles, passenger cars, trucks, buses, etc. ,
It is used in a wide range of applications. In such a tire tread, the design elements, that is, the blocks are repeated in a continuous pattern in the circumferential direction of the tire, so that the air contained in the grooves between the blocks is compressed and released as the tire rolls. In addition, as the tires roll, the pulse vibrations emitted from each block occur repeatedly, creating compression waves in the nearby air, producing pattern noise or impacting sound, and this noise matches the resonance frequency of each part of the vehicle. Its value increases. Traditionally, to reduce this type of noise, the noise is dispersed over a wide frequency band to make it less noticeable, and to prevent the noise from increasing due to resonance.
A variable pitch method that improves the arrangement of blocks is known. The variable pitch method involves arranging several types of blocks with different circumferential lengths in the circumferential direction of the tire, and changing the time interval of the pulse noise or vibration generated when the blocks leave the ground contact surface to a specific frequency. This is a method to prevent noise concentration. However, even if a design element has a good dispersion degree in terms of frequency modulation theory, if the ratio of the longest block length to the shortest block length is large, the difference in stiffness of the design elements will be large, resulting in vibration characteristics during tire rolling. In addition to having an adverse effect on the tire wear pattern and causing uneven wear in the tire wear pattern, employing blocks with different circumferential lengths in each block row also requires a great deal of effort in production. An object of the present invention is to provide a low-noise block pattern tire that is easy to produce and can reduce the noise level. [Technical means] The present invention provides at least two tires extending in the circumferential direction of the tire.
In a tire with a block pattern in which a plurality of block rows are formed in the tread portion by vertical grooves and horizontal grooves that intersect with the vertical grooves, the block rows are blocks having the same length in the circumferential direction. One basic block row is lined up at the same circumferential pitch, and the blocks adjacent to the blocks in the basic block row in the tire axial direction are shifted in the tire circumferential direction from the blocks in the basic block row. The blocks in the phase difference block array are identical and have a circumferential length longer than the circumferential length of the blocks in the basic block array, and the number of blocks in the phase difference block array is is the same as the number of blocks in the basic block row, and the amount of positional deviation of the block in the phase difference block row with respect to the block in the basic block row adjacent in the tire axial direction is the same as the number of blocks in the phase difference block row adjacent in the circumferential direction. This is a low-noise tire characterized by two blocks each being different. [Operation] Each block of the basic block array and the phase difference block array is formed to have the same circumferential length. Therefore, the difference in rigidity in the circumferential direction is reduced, uneven wear is reduced, and vibration characteristics are improved. Further, there is one basic block sequence, and the blocks are arranged at the same pitch in the circumferential direction, whereas the phase difference blocks are arranged with sequential phase differences with respect to the blocks of the basic block sequence. This prevents synchronization of grounding and enables the dispersion of noise frequencies, resulting in lower noise. It has also been confirmed that the unit block length of the phase difference block array is made larger than the unit block length of the basic block array, which improves wear resistance and helps reduce noise. Furthermore, as described above, since the blocks in the same circumferential direction are basically used to form the phase difference block array, the mold can be manufactured easily and productivity can be improved. An embodiment of the present invention will be described below based on the drawings. In FIG. 1, which shows the tread section unfolded, the low-noise tire has at least two longitudinal grooves extending in the circumferential direction of the tire, in this example two longitudinal grooves, and a lateral groove intersecting the longitudinal grooves in the tread section. As a result, a basic block row A is formed in the tread portion, in which blocks A1, A2, and A3 are lined up in the circumferential direction on the tire equator, and blocks B1, B2, B3, and B3 are arranged on both sides of the basic block row A.
Phase difference block rows B and C in which C1, C2, and C3 (not shown) are arranged in the circumferential direction are provided. The blocks A1 to A3 of the basic block row A have the same circumferential length la and are arranged circumferentially at the same circumferential pitch. Each block B1 to B is included in the phase difference block rows B and C.
3. C1 to C3 also have the same circumferential lengths lb and lc, respectively, and have longer circumferential lengths than the circumferential length la of the blocks in the basic block row, and furthermore, each of the block rows A and B , C are both set to the same number. In addition, block B1 of the phase difference block arrays B and C
~B3, C1-C3 are blocks of the phase difference block row that are adjacent to blocks A1-A3 of the basic block row in the tire axial direction, and are positioned shifted in the tire circumferential direction from blocks A1-A3 of the basic block row. They are arranged with their positions shifted by amounts S1, M1, L1, S2, M2, and L2. The amount of positional deviation refers to the circumferential edge of the block adjacent in the tire axial direction to the unit blocks A1, A2, A3... of the basic block row A, and the circumferential edge of the unit block A1, A2, A3... of the basic block row A. For phase difference block row B, it is the distance in the circumferential direction between the upper edges in the figure, and for phase difference block row C, it is the distance between the lower edges in the figure. Furthermore, the positional deviation amount S1, M1, L1, S2, M2, L2
is made different for each two blocks B1 to B3 and C1 to C3 of the phase difference block rows adjacent in the circumferential direction. In this example, for example, block B1 of the phase difference block array B is displaced in the circumferential direction from block A1 of the basic block array A adjacent in the axial direction by a displacement amount S1, and block B2 is displaced in the axial direction. Block A2 of the adjacent basic block row A is displaced by a positional deviation amount M1 in the circumferential direction, and block B3 is similarly displaced from the basic block row A.
Positional deviation L1 in the circumferential direction with respect to block A3
The position is shifted. Here, the positional deviation amount S1, M1, L1 is S1<M1<L1
This positional shift amount can be repeated periodically or randomly in the circumferential direction. On the other hand, blocks C1 to C3 of the phase difference block array C
Similarly, the blocks are shifted from the blocks in the basic block array A by the shift amounts S2, M2, and L2. By arranging phase difference block arrays with different positional deviations on the left and right sides of the basic block array in this way, it is possible to reduce synchronization when the blocks touch the road surface. Note that each block in the portion not shown in the figure is formed by repeating the block shown in the figure. In addition to the three different types of blocks in the circumferential direction, the phase difference block array B can have more types of blocks, or can have two types. Furthermore, by making each block in the phase difference block array longer than the circumferential length of the blocks in the basic block array, the rigidity of the block can be increased and the wear resistance of the tread portion can be improved. Examples Tires for motorcycles having a tire size of 4,60-18 were manufactured as trial tires as shown in Tables 1 and 2 (Example) and tires shown in FIG. 2 (Comparative Example). The amount of positional deviation is S1=S2, M1=M2,
L1=L2, and are represented as S, M, and L in the table. Each numerical value in FIG. 2 is in mm, and numerical values other than the above-mentioned numerical values in the example tire are determined according to the dimensions in FIG. 2. Noise test is air pressure 1.75
Kgf/cm ² and a load of 100 kgf, in accordance with the tire noise test method specified in JASO.C606, with a sound collecting microphone directly beside the tire and 50 cm from the center of the tire width.
The tire was installed at a height of 25cm above the ground surface, and the drum was driven in an anechoic chamber, and measurements were taken while the tire was rotating. Note that the patterns of the example and comparative example had exactly the same shape except that there was a phase difference. As shown in FIG. 3, the measurement results of the noise level show that the example product has a reduced noise level. [Effect of the invention] As described above, in a tire with a block pattern having a plurality of rows of blocks, the blocks can be mutually connected.

【table】

【table】

[Table] By shifting, it is possible to prevent synchronization of the sound generated when the block contacts the road surface, reduce the absolute value of the noise level, and furthermore, it is possible to reduce the noise due to frequency dispersion.

[Brief explanation of drawings]

FIG. 1 is a partial plan view of the tread portion of the tire of the present invention, FIG. 2 is a partial plan view of the tread portion of a conventional tire, and FIG. 3 is a graph showing the relationship between speed and noise level.

Claims (1)

[Scope of Claims] 1. A tire with a block pattern in which a plurality of block rows arranged in the circumferential direction are formed in the tread portion by at least two longitudinal grooves extending in the circumferential direction of the tire and lateral grooves that intersect with the longitudinal grooves. In this case, the block row includes one basic block row in which blocks having the same circumferential length are lined up at the same circumferential pitch, and blocks adjacent to the blocks in the basic block row in the tire axial direction. Blocks are composed of a series of phase difference blocks arranged in the tire circumferential direction with their positions shifted in the tire circumferential direction, and the blocks in the phase difference block series have a length in the circumferential direction that is identical and longer than the circumferential length of the blocks in the basic block series. and the number of blocks in the phase difference block train is the same as the number of blocks in the basic block train, and the number of blocks in the basic block train is A low-noise tire characterized in that the amount of positional shift is different for each two blocks of a phase difference block row adjacent in the circumferential direction.