JPH0755605B2 - Two-wheeled vehicle tires - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motorcycle tire having improved cornering performance, especially in a soft tire for running on uneven terrain.

[Conventional technology]

For example, a motocross tire employs a so-called small land pattern block pattern a as shown in FIG. 8 in order to satisfy sufficient grip performance, traction performance, and soil removal performance on rough terrain.

In addition, since the motocross course is often constructed by cutting out the mountains, it tends to get bogged down in the rain, so under these circumstances, the block b can bite into the soft road surface and grasp the road surface firmly on the kicking side. A wet type in which the rising angle of the block end surface c on the stepping side is deepened to 4 to 5 ° is used.
However, although the course in rainy weather becomes mud, there are also soft road surface parts due to differences in soil and topography, and in many cases it hardens gradually due to weather recovery. The running performance of is also required.

[Problems to be Solved by the Invention]

However, the conventional wet type adopts a deep rising angle as described above, so the block rigidity is low, and therefore the grip force becomes insufficient on hard road surfaces, especially slipping during cornering etc. Is extremely bad. It should be noted that this tendency is more noticeable in the front wheels on the non-driving side.

Therefore, the present inventor has devised to improve the cornering performance on a hard road surface while maintaining the road surface gripping property on a soft road surface by making the end surface rising angle shallow only in the block located on the tread shoulder side.

This is because when traveling on a soft road surface, the bank angle is small, that is, straightening and cornering are performed with the vehicle body standing upright, and therefore the influence of the shoulder block on the soft road surface is relatively small.

However, it has been found that it is difficult to obtain sufficient road surface gripping property and block rigidity only by making the rising angle shallow in this device.

An object of the present invention is to provide a tire for a motorcycle capable of solving the above-mentioned problems, based on the provision of a slope portion having a deep rising angle and a slope portion having a shallow rising angle on the end surface of the shoulder block.

[Means for Solving the Problems]

To achieve the above-mentioned object, the tire for a motorcycle of the present invention comprises a tire tread portion, and a tread portion having a block pattern in which blocks having end faces to be a protruding side and a stepping side when the tire is rotated are arranged side by side, and a side portion. A carcass having a carcass cord that passes through the wall part and is folded back at the bead core of the bead part and arranged at an angle of 30 to 40 ° to the tire equator is arranged, and the surface area S1 of the tread part and the total surface area of the block are the land area. The land ratio S2 / S1, which is the ratio to S2, is set to be larger than 0.15 and smaller than 0.25, while the length L that is 1/4 times the tread width TW is separated from the tire equator in the axial direction of the tire. A first section line is defined between the reference line 1 and the tread edge with reference to the line l.
x1, the 2nd division line x, the 1st division area y1, the 2nd division area y2, and the 3rd division area toward the tire axial direction outer side
The block in which the tire axial direction center z1 is located in the first divisional region y1 including the first division line x1 is divided into 3 to 6 with respect to the plane including the tire axis at the end face.
A sloped portion having a bottom length at an angle of 8 ° and a sloped portion having a bottom length at an angle of 8 to 12 ° are provided, and a tire axial center z2 is provided in a second sectioned region y2 including the second section line x2. The block located is 3 to 6 with respect to the plane including the tire shaft on the end face thereof.
The block having a sloped portion having a bottom length at an angle of 13 ° and a sloped portion having a bottom length at an angle of 13 to 17 °, in which the tire axial center z3 is located in the third divisional region y3, Has a sloped portion having a bottom length at an angle of 3 to 6 ° with respect to a plane including the tire axis and a sloped portion having a bottom length at an angle of 18 to 22 °.

Further, it is preferable that the first, second, and third sections are formed to have the same width.

[Action]

In this way, a block having an end face composed of a slope portion rising at a shallow angle and a slope portion rising at a deep angle has a soft road surface gripping property as compared with a block made of one slope rising at an intermediate angle, It is excellent in both block rigidity, and therefore by arranging such a block on the tread shoulder part, it is possible to improve the grip performance when cornering on a hard road surface and to maintain the road surface gripability on a soft road surface. You can

In addition, the rigidity of the block that divides the shoulder part into three parts and arranges it in each divided area, that is, the grip performance on the hard road surface, is increased as it approaches the shoulder edge, and the stress that increases with the camber angle is countered, so that the running stability is further improved. sell.

〔Example〕

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

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a plan view showing its block pattern.

In the figure, a motorcycle tire (hereinafter referred to as a tire) 1
Has a tread portion 2 provided with the block pattern P, a sidewall portion 3 extending inward in the tire radial direction from both ends thereof, and bead portions 5 and 5 located at the radial inner end of the sidewall portion 3. A toroidal carcass 7 passing through the sidewall portion 3 and the tread portion 2 is bridged between the bead cores 6 provided in the bead portion 5, and a breaker 9 is arranged on the outer side in the radial direction.

The tread portion 2 extends on the crown of the carcass 7 outward from the center of the crown substantially in parallel to the ring portion thereof, and has a tread width TW that is a straight line width thereof that exceeds the maximum width of the sidewall portion 3. Camber thrust is maintained during cornering.

The carcass 7 has a carcass cord with respect to the tire equator.
In this example, the two plies 7A and 7B are arranged at an angle of 30 to 40 °.
Both ends of each ply are folded back from the inside to the outside around the bead core 6, and the edge ends of the sidewall portion 3 differ in height position.

The carcass cord has an initial tensile modulus of 850 kg /
An organic fiber cord of about mm ² such as rayon, polyester or nylon can be preferably used. In this example, the carcass 7 has a cross ply structure in which cord angles of the plies 7A and 7B are crossed with each other.

A bead apex 10 made of hard rubber whose thickness gradually decreases from the bead core 6 in the sidewall direction is arranged in a portion surrounded by the carcass main body portion and the folded portion to enhance tire lateral rigidity.

The breaker 9 is composed of one ply in this example, which is provided with a breaker cord that is inclined at about the same degree as the carcass cord, that is, at an angle of about 30 to 40 ° with respect to the tire equator. The carcass 7 is covered and protected by being arranged with a width of 90%. As the breaker cord, the same or different organic fiber cord as the carcass 7 is used, and the breaker cord and the carcass ply 7B on the adjacent side are arranged with their cord angles intersecting. Also, the carcass 7,
In the tread portion 2 in which the breaker 9 is embedded, a block pattern P including short blocks B ... Is formed.

In this example, the block putter P is provided on the tread crown portion 2A defined between the reference lines 1 and 1 in the circumferential direction that separates the length L of 1/4 times the tread width TW from the tire equator CO in the tire axial direction. It consists of a central block group arranged and a shoulder block group arranged in the shoulder portion 2B defined outside the reference line 1. Each block B0 that constitutes the central block group
As shown in FIG. 3, each groove surface B0s on the kicking side and the stepping side when the tire rotates is formed by an inclined surface inclined at a rising angle θ of 3 to 6 ° with respect to a plane including the tire shaft. As a result, a strong road surface gripping property is exhibited during straight running on a soft road surface.

Further, in this example, the shoulder portion 2B is divided into first, second and third sections having the same width toward the tire axial direction outer side by the first and second section lines x1 and x2 parallel to the reference line l. Area y1, y2,
The shoulder block group is divided into y3, whereby the first axial direction block z1 is located in the first divisional region y1 including the first division line x1.
And a second shoulder block B2 where the tire axial center z2 is located in the second sectional area y2 including the second section line x2, and a third shoulder block B3 where the tire axial center z3 is located in the third sectional area y3. It is divided into blocks B3 ...

Here, the end surface B1S of the block B1 is, as shown in FIGS. 4 and 5 (a) and (b), 3 to 3 with respect to a plane including the tire shaft in a direction in which the block B1 has a bottom length. Slope part B1a inclined at a rising angle α1 of 6 ° and 8-12
It is formed by two planes including a slope portion B1b inclined at a rising angle β1 of ゜, and similarly, the block B2 has its end face B2S.
As shown in FIGS. 6 (a) and 6 (b), a slope portion B2a having a rising angle α2 of 3 to 6 ° and a slope portion B2b having a rising angle β2 of 13 to 17 °, and the block B3 The end surface B3s of the slanted surface B3s has a rising angle α3 of 3 to 6 ° as shown in FIGS. 7 (a) and (b).
a and a slope portion B3b that inclines at a rising angle β3 of 18 to 22 °
And are formed respectively. (The slope portions B1a, B2a, B3a on the side having a deeper rising angle are collectively referred to as the slope portion Ba, and the other slope portions B1b, B2b, B3b are referred to as the slope portion Bb.) A block having two sloped portions is superior in road gripping property and block rigidity to a block having one sloped surface having a rising angle in the middle between the two sloped portions. By arranging in 2B, it is possible to improve cornering performance on a hard road surface turning at a deep bank angle without impairing the road surface gripping performance on a soft road surface turning at a relatively shallow bank angle. Further, in the shoulder block group, the rigidity of the block located outside is increased in response to the stress increased by the increase of the bank angle, so that the cornering performance can be further improved.

The rising angles α1, α2, α3, β1, β2,
β3 is a value obtained by various experiments. When the rising angles α1, α2, α3 are less than 3 ° and when the rising angles β1, β2, β3 are less than 8 °, less than 13 °, less than 18 °, respectively. The rigidity of each block B1, B2, B3 is insufficient. When the rising angles α1, α2, and α3 exceed 6 °, and the rising angles β1, β2, and β3 are 12 ° and 17 °, respectively.
When it exceeds 22 °, the soft road surface gripping property becomes insufficient.

In this example, it is preferable that the slope portion Ba and the slope portion Bb have substantially the same width, and that the slope portion Bb is arranged on the side closer to the tire equator.

This is due to the soft road surface gripping effect due to the deep rising angle of one block by making the width almost the same,
This is because both the effect of improving the block rigidity due to the shallow rising angle can be further enhanced, and because the camber thrust during cornering acts as a tensile force on the tire equator side of the block, the slope portion Bb
By arranging the tire on the equator side of the tire, the proof stress of the block can be further increased.

Note that such an effect is obtained by comparing the land area S2, which is the total surface area of the block, with the land surface area S2, which is the ratio of the surface area S1 of the tread portion 2.
More effective when / S1 is greater than 0.15 and less than 0.25.

[Advantages of the Invention] As described above, the tire for a motorcycle of the present invention is a block including an end surface having a slope portion that rises at a shallow angle in a predetermined angle range and a slope portion that rises at a deep angle in a shoulder portion. Because of the provision of the corners, the cornering performance on a hard road surface can be improved while maintaining the soft road surface gripping property. In particular, since the shoulder portion is divided into three regions and the outer block rigidity is higher than that of the inner portion, cornering performance can be further improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a plan view showing a part of the block pattern, FIG. 3 is a sectional view showing a block in a central block group, and FIG.
5 (a) -a perspective view of a block to be arranged in the section area of FIG.
6B is a cross-sectional view thereof, FIGS. 6A to 6B are cross-sectional views of blocks arranged in the second division area, and FIGS. 7A to 7B.
Is a cross-sectional view of a block arranged in the third divisional area, and FIG. 8 is a plan view showing a conventional technique. 2 ... Tread part, 3 ... Sidewall part, 5 ... Bead part, 6 ... Bead core, 7 ... Carcass, B, Bo, B1, B2, B3 ... Block, Bos, B1s, B2s, B3s ... ... End face, α1, α2, α3, β1, β2, β3 ... Rise angle.

Claims (2)

[Claims] 1. A tire tread portion is provided with a block pattern in which blocks having end faces that are a protruding side and a stepping side when a tire is rotated are juxtaposed, and passed through the tread portion, sidewall portion, and folded back at a bead core of a bead portion. In addition to arranging the carcass with the carcass cord arranged at an angle of 30 to 40 degrees to the tire equator,
The land ratio S2 / S1 which is the ratio of the surface area S1 of the tread to the land area S2 which is the total surface area of the block is larger than 0.15 and 0.25.
While making it smaller, 1/4 of the tread width TW from the tire equator
A reference line l in the circumferential direction, which is a double length L separated in the tire axial direction.
With reference to the first line between the reference line 1 and the tread edge
Section line x1 and second section line x2 toward the outer side in the axial direction of the tire, a first section region y1, a second section region y2, and a third section region
And the first division line x1
The block in which the tire axial center z1 is located in the first sectioned region y1 including is a slope portion having a bottom length at an end surface of 3 to 6 degrees with respect to a plane including the tire axis, and 8 to 12 degrees. And a slope portion having a bottom length at an angle of 2
The center of the axial direction z2 of the block is located in the second section y2 including the area of the slope of the end surface of which is 3 to 6 degrees with respect to the plane including the tire axis, and 13 to 17 degrees. And a slope portion having a bottom length at an angle of 3
The block in which the axial center z3 of the tire is located at the end of the block includes a slope portion having a bottom length at an angle of 3 to 6 degrees and a slope portion having a bottom length at an angle of 18 to 22 degrees with respect to a plane including the tire axis. A motorcycle tire with parts and parts. 2. The first, second and third sections y1, y2 and y3
The tire for a motorcycle according to claim 1, wherein the tires are divided into the same width.