JPH0427681Y2 - - Google Patents

Description

[Detailed explanation of the idea]

TECHNICAL FIELD The present invention relates to a low-noise tire that can reduce noise during running without impairing traction, and can be particularly suited for use in off-road motorcycles. In general, motorcycle tires, especially motorcycle tires used on Oyaroad, are separated and divided by horizontal grooves a extending in the axial direction of the tire, as shown in Fig. 1, in order to increase the traction force. Blocks b arranged along guiding surface
A tread pattern d having a tread pattern d is widely used. However, in such a tread pattern d,
When running at high speed on a paved road surface, the block b is discontinuous at the center of the tread where it makes particularly strong contact with the ground, the contact of the block b with the ground becomes discontinuous, and the impact sound of the block b striking the ground becomes louder. The present invention was completed as a result of research on block arrangement in the center of the tread, and aims to provide a low-noise tire that can reduce noise without impairing traction force and can solve the above-mentioned problems. An embodiment of the present invention will be described below based on the drawings. In FIG. 2 showing the tread portion, the low noise tire 1 has lateral grooves G1, G2,
A block group P1 consisting of blocks A1, A2, A1, A2... which are continuous in the circumferential direction along the tire equatorial plane X with G1, G2... separated, and blocks B1, B2 which are continuous in the tire circumferential direction on both sides, A block group P2 consisting of B1, B2... and blocks C1, C2, C1,
In addition to arranging block group P3 consisting of C2...,
A rectangular parallelepiped-shaped block D...
Other block groups P4 and P5 consisting of E... are attached. In this specification, the central part of the tread
CR refers to the area of width W centered on the tire equatorial plane X where the tire tread actually makes contact with the ground. Each block A1, A2..., B1, B2..., C1, C2... forming the block groups P1, P2, P3...
is formed by the alternating repetition of a basic block F1, both of which are continuous in a straight line in the circumferential direction and have the same shape, and a block F2, which is the basic block F1 reversed symmetrically with respect to the tire circumference line. . Blocks F1 and F2 have two connecting sides 6a and 6b that are parallel to the tire equatorial plane
In this example, the connecting sides 6a and 6b are oblique sides 9 that are inclined at the same angle in a V-shape from both ends of the short side 5 toward the long side 4.
a, 9b, and the oblique side 9 extending from the other end.
The hypotenuse 10a intersects with the tire axial direction axis Y perpendicular to the tire equatorial plane X at a larger angle than that of a and 9b.
10b, and small horizontal sides 11a and 11b that are parallel to the tire axis direction Y that connects the other ends of the oblique sides 10a and 10b and both ends of the long side 4, and thus are the connecting sides of blocks F1 and F2. 6a and 6b are hollow in the shape of a dogleg and are symmetrical with respect to the tire axial direction line Y, and as a result, the blocks F1 and F2 are formed by the base formed by the short side 5, the oblique sides 9a and 9b, and their extensions. It has an octagonal shape with wing parts 13 and 14 extending from the top 12. Also, adjacent blocks F1 and F2 have horizontal grooves between them.
By forming G1 and G2 to be relatively narrow, the projection range of the length L sandwiched by the projection lines K1 and K2 projected from the upper and lower edges of the long side 4 to the tire equatorial plane X, overlaps each other. Overlapping projection portions of length L1 are sequentially formed. Adjacent blocks F1, F2...
By forming such an overlapping projection portion between them, discontinuity in ground pressure at the tread center CR in the circumferential direction of the tire 1 is reduced, and impact noise is reduced. Here, the length of the overlap projection part
It is preferable that L1 be within 40% of the length L of the projection range. This length L is the width of the lateral grooves G1 and G2 that divide blocks F1, F2... in the circumferential direction, and the lateral grooves.
It can be adjusted by adjusting the inclination angle of G1 and G2, that is, the shape of blocks F1 and F2, etc., but this length L1 is 40% of the above.
If it exceeds this, the traction force will decrease. Furthermore, each block of block groups P1, P2, and P3
A1, A2..., B1, B2..., C1, C2... are made by placing the basic block F1 of the same shape and the reversed block F2 of the shape reversed along the tire circumference line, respectively, as described above. They are arranged alternately,
Therefore, the horizontal groove separating each block F1, F2
G1 and G2 are connecting sides 6a and 6b of blocks F1 and F2
are inclined in opposite directions alternately in the circumferential direction in accordance with the shape of. When the lateral grooves G1 and G2 are all inclined in the same direction, when the tread surface makes contact with the ground, it is subjected to uneven stress corresponding to the direction of inclination, which impairs the smoothness of steering wheel operation. Also, the inclination angle α of the lateral grooves G1, G2, that is, the oblique sides 9a, 9b or the oblique sides 10a, 10
The angle at part b with respect to the tire axial direction line Y is:
The range is ±30° to ±80°. If this angle exceeds 80°, the traction force will decrease, while if the angle is small, the wear resistance of the block will decrease and noise reduction will not be achieved sufficiently. Next, the lateral sides 11a and 11b of the blocks F1 and F2 are most likely to be deformed and worn by the road surface during running, so the axial length of the lateral sides 11a and 11b should be at least 5% of the block width h. is desirable.
However, if it exceeds 50%, it becomes difficult to reduce noise. Furthermore, block D of the block groups P4 and P5...
E... has its upper and lower edges aligned with each block A1, A2..., B1,
The horizontal sides 11a, 11b of B2..., C1, C2... are arranged at different positions in the tire circumferential direction, and the block groups A1, P3 of each block group P1, P2, P3 are
A2…, B1, B2…, C1, C2… each horizontal side 1
Also in 1a and 11b, it is desirable that the pitches are staggered from each other so that their circumferential positions do not overlap. In this way, the low-noise tire of the present invention is based on the fact that the block has overlapping projected parts that overlap each other by projecting the parts, and thereby prevents the overlapping of the pumping sounds and maintains traction while reducing noise. It can be suitably used for motorcycles. Example An example product of the tread pattern shown in Fig. 2,
Comparative example product 1 shown in Fig. 1 and shown in Fig. 3,
A cross-ply motorcycle tire with a tire size of 5.10-17 and 4PR. was prototyped using Comparative Example Product 2 with a tread pattern having a trapezoidal block e and a rectangular parallelepiped block f, and an internal pressure of 1.5
Kg/cm ² , under driving conditions with a load of 120 kg, place a sound-collecting microphone directly next to the tire with a distance of 50 cm from the center of the tire width.
Measured in an anechoic chamber at a height of 25 cm from the ground contact surface (based on the tire noise test method specified in JASO C606). The detailed specifications of the example product are as follows.

【table】

[Table] Figure 4 shows the results of the noise test. It is clear that the example product has a reduced noise level.

[Brief explanation of the drawing]

FIG. 1 is a partial plan view showing the tread portion of a conventional tire, FIG. 2 is a partial plan view showing an embodiment of the present invention, and FIG. 3 is a partial plan view showing the tread portion of another conventional tire. FIG. 4 is a diagram showing the relationship between noise level and speed. A1, A2, B1, B2, C1, C2...Block,
G1, G2...Horizontal groove, L1...Length of overlapped projection part,
P1, P2, P3...Brock County, X...Tire equatorial plane.

Claims (1)

[Scope of utility model registration request] At the center of the tread where the tire tread makes contact with the ground,
A group of blocks that are arranged in a straight line in the circumferential direction across a lateral groove and that are along the tire's equatorial plane X.
P1 and block groups P2 and P3 arranged on both sides thereof are provided, and each block group P1 to P3 consists of a basic block and a block obtained by inverting this basic block symmetrically with respect to the circumferential line. The block is composed of the blocks adjacent to each other in the circumferential direction, and each block has a long side 4 and a short side 5 in the circumferential direction tilted in a V-shape from both ends of the short side 5 toward the long side 4. hypotenuses 9a, 9b and hypotenuses 9a, 9b
The oblique side 9 with respect to the tire axial direction line Y from the other end
The hypotenuse 10a intersects at a larger angle than a and 9b,
10b, and horizontal sides 11a, 11b parallel to the tire axial direction line Y connecting the other ends of the oblique sides 10a, 10b and both ends of the long oblique side 4, and having a length of 5% or more and 50% or less of the block width h. Connecting side 6 consisting of
6a and 6b, and each of the circumferentially adjacent blocks has overlapping projection portions that overlap each other in a projection plane onto the tire's equatorial plane.