JP2799010B2 - Motorcycle tires - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for a motorcycle capable of increasing indexing power and running stability when running on uneven terrain, particularly on soft soil.

[Conventional technology]

In motorcycles traveling on uneven terrain, there is a demand for safe and prompt traveling regardless of the state of the road surface.

On the other hand, on uneven terrain, there are a wide variety of conditions including hard soil roads, soft soil roads, muddy roads, and sandy roads, and multiple patterns are prepared according to these road surface conditions. And then use selective.

Especially for soft roads, muddy roads, tires that run on soft roads such as sandy ground, it is not enough to obtain index power with grip like tires that run on hard soil roads,
The tread surface forms a block pattern composed of a plurality of blocks formed by deep grooves, and at the same time, the rising angle of the block mural is increased, and the block is bitten into the road surface, whereby the index force is determined by the wall portion and angle of the block. Was getting.

[Problems to be solved by the invention]

However, even when the tread portion is configured as described above, the index force tends to be still insufficient, and there has been a demand from customers for further increase in the index force for soft soil traveling.

The inventor has conducted intensive studies and found that by providing semi-ribs extending along the tire axle method between blocks in the tire circumferential direction, soft soil on the traveling road surface can efficiently mesh with the block wall surfaces and increase the tire's index force. I found it.

An object of the present invention is to provide a motorcycle tire capable of responding to the above-mentioned demand by increasing the indexing force even on a soft soil road surface by providing semi-ribs extending in the tire axial direction in lateral grooves arranged between blocks. And

[Means for solving the problem]

The present invention forms a block pattern having a block divided by the groove by providing a groove including a center lateral groove which passes through the tire equator in the tire axial direction and is separated in the tire circumferential direction in the tread portion, and The height of the center lateral groove is approximately 1/3 or more and 1/2 or less, the length in the axial direction of the tire is 40% or less of the tread width, and the tire circumference at the upper end is approximately at the middle position of the center lateral groove in the tire circumferential direction. Thickness in the direction
This is a motorcycle tire provided with semi-ribs having a length of 1 mm or less and extending substantially in the circumferential direction of the tire so as to expand toward the bottom toward the bottom.

[Action]

Since the semi-ribs having the above-described configuration and having a wedge shape are provided, the soil, sand, or mud that has entered the lateral grooves is pressed toward the wall surfaces of the blocks by the semi-ribs, and the pressing force reduces the density of the sediment interposed in the lateral grooves. As a result of the increase and the removal of the water contained in the earth and sand, the block biting property of the block is improved, and the indexing force can be increased by the engagement between the block and the earth and sand even when traveling on soft soil.

〔Example〕

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

In the figure, a motorcycle tire 1 of the present invention includes a block B provided around a tread portion 2 and a lateral groove 3 interposed between the blocks B.
Are provided with semi-ribs 4.

The motorcycle tire 1 includes a tread portion 2 having the blocks B,..., Sidewall portions 13 extending radially inward from both ends thereof, and the sidewall portions.
13 having bead portions 15, 15 located at the radial inner end,
Between the bead cores 16 provided in the bead portion 15, a toroidal carcass 17 passing through the sidewall portions 13, 13 and the tread portion 2 is bridged, and a belt layer 19 is disposed radially outside thereof. I have.

The tread portion 2 extends outwardly from the center of the crown substantially in parallel with the loop portion on the crown of the carcass 17 and has a cross-sectional shape in which the tread width TW, which is the straight width thereof, exceeds the maximum width of the sidewall portion 13. Camber thrust during cornering is maintained.

In the present embodiment, the carcass 17 is composed of two carcass plies 17A and 17B in which fiber cords such as nylon and polyester are arranged at an angle of 30 ° to 90 ° with respect to the equator of the tire. A cross-ply structure in which the cord angles of 17A and 17B cross each other is adopted.

In this embodiment, the belt layer 19 has a thickness of 30 with respect to the tire equator C.
It consists of a single belt ply with a carcass cord inclined at an angle of ゜ to 40 ゜, and the tread width TW is 60 to 90 ゜
By arranging the carcass 17 in the width of ゜, the carcass 17 is covered and protected in the tread portion 2 and the rigidity of the tread portion 2 is increased. The belt cord is the carcass 17
The same or different fiber cord as the carcass cord is used.

The tread portion 2 has a plurality of longitudinal grooves 21 extending in the tire circumferential direction, and a plurality of center lateral grooves 3 extending in the tire axial direction across the tire equator C between the longitudinal grooves 21. A groove G is provided, and a block pattern 5 having a plurality of blocks B... Divided by the groove G is formed.

In the present embodiment, in the center of the tread portion 2 through which the tire equator C passes, a first block row B1 having a small groove having a long side in the tire axial direction and a small depth passing on the tire equator C line, A second block row B2 composed of a block and a rectangular block arranged laterally in the tire axial direction; a third block row B3 arranged symmetrically with respect to the tire equator C; Are arranged at substantially equal pitches in the tire circumferential direction, and are provided around the outer peripheral surface of the tread portion 2.

Each of the blocks B forming the first, second, and third block rows B1, B2, and B3 has a large rising angle of the block wall surface 22 facing in the circumferential direction. Standing at an angle of ゜.

The center lateral grooves 3 are formed between the respective block rows B1, B2, B3, B1,..., And the semi-ribs 4 are provided at substantially middle positions of the center lateral grooves 3 in the tire circumferential direction.

The semi-ribs 4 are in the form of elongated rectangles whose longitudinal direction is the tire axial direction as shown in FIGS. 2 and 3, and the height H is set to be not less than 1/3 and not more than 1/2 of the depth D of the center lateral groove 3. The length L of the semi-rib 4 in the tire axial direction is 40% of the tread width TW.
It is as follows.

If the height H of the semi-ribs 4 is less than 1/3 of the depth D of the center lateral groove 3, the semi-ribs 4 are small and run on soft soil because the pressing force for pressing the earth and sand entering the grooves toward the block B is insufficient. Insufficient indexing power. On the other hand, if it exceeds 根, the strength of the root portion is insufficient at the time of biting of earth and sand, and the semi-ribs 4 are easily damaged.

On the other hand, when traveling on a soft road surface such as soil and sand, the bank angle is usually small, that is, the straight running and cornering are performed with the vehicle standing, so that the influence of the lateral groove located on the shoulder side on the soft road surface is relatively small. Therefore, even if the length L of the semi-rib 4 is increased beyond 40% of the tread width TW, the indexing force does not increase and there is no effect on cornering.

Further, the semi-rib 4 has a thickness T in the tire circumferential direction at the upper end thereof.
Is set to 1 mm or less and extends substantially in the circumferential direction of the tire so as to expand toward the bottom toward the bottom. In the present embodiment, the surface 24 facing the circumferential direction of the semi-rib 4 and the groove bottom surface 25 of the center lateral groove 3 are connected by an arc surface having a radius R substantially equal to the height H. If the thickness T is 1 mm or more, the earth and sand that has entered the center lateral groove 3 is branched, and the earth and sand cannot be smoothly moved toward the wall surfaces 22 and 22 facing the block.

The semi-ribs 4 are organically combined with each other by restricting the height H, regulating the thickness T, and expanding the hem in the tire circumferential direction, so that the soil and sand that have entered the center lateral groove are blocked on both sides. By moving toward the wall surfaces 21 and 21 and pressing against the wall surfaces 21 and 21, even when traveling on the ground of soft soil, the meshing can be smoothed and the indexing force can be increased.

〔Concrete example〕

A prototype tire having a tire size of 110 / 90-19 K990 and having the configuration shown in FIGS. 1 to 3 was prototyped, mounted on the rear wheel of a 250 cc motocross motorcycle, and tested on a motocross course. 80/1 tire size on the front wheels of the test car
A conventional tire having a pattern of 00-21 K990 and having no pattern shown in FIG. 4, that is, having no semi-rib was mounted.

When testing, use the same tag on the front wheels of the test vehicle. Ears were attached to both front and rear wheels (comparative example) to compare the performance.

The test was performed by a dedicated rider, and the rider's feeling was evaluated using a five-point method.

 Table 1 shows the test results.

〔The invention's effect〕

As described above, the motorcycle tire of the present invention has wedge-shaped semi-ribs with height, width, and thickness regulated in the center lateral groove between the blocks, so that the indexing force is enhanced on a soft soil road surface and the ground is uneven. The driving ability in can be improved.

[Brief description of the drawings]

1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a plan view showing a block pattern of the tread portion, FIG. 3 is an end view showing the AA line on an enlarged scale, FIG. FIG. 3 is a plan view showing a conventional tread portion pattern. 2 ... tread, 3 ... center lateral groove, 4 ... semi-rib, 5 ... block pattern, B ... block, C ... tire equator, D ... center lateral groove depth, H ... semi-rib height , G: Groove, L: Semi-rib length, T: Semi-rib thickness, TW: Tread width.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-64004 (JP, A) JP-A-62-157808 (JP, A) JP-A-63-130408 (JP, A) 56406 (JP, U) Japanese Utility Model Showa 62-151102 (JP, U) Japanese Utility Model Showa 62-196705 (JP, U) Japanese Utility Model Application Showa 61-113104 (JP, U) JP 4-33641 (JP, B2) 62-28281 (JP, Y2) 5-24561 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60C 11/11 B60C 11/08 B60C 11/04

Claims (1)

(57) [Claims] 1. A block pattern having a block divided by the groove is formed in a tread portion by providing a groove including a center lateral groove which passes through a tire equator in a tire axial direction and is separated in a tire circumferential direction. At the center of the center lateral groove in the tire circumferential direction, the height of the center lateral groove is 1/3 or more and 1/2 or less, the length in the tire axial direction is 40% or less of the tread width, and the tire at the upper end. The circumferential thickness is
A motorcycle tire having a semi-rib that is 1 mm or less and extends substantially in the circumferential direction of the tire so as to expand toward the bottom toward the bottom.