JP4145397B2 - Pneumatic tires for motorcycles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire for a two-wheeled vehicle in which a zigzag center land portion having a relatively narrow width is formed in a center region of a tread portion. More specifically, the present invention relates to a so-called rain groove wandering of the tire. Improve sex.
[0002]
[Prior art]
A pneumatic tire for a motorcycle is not used only on a normal smooth road surface paved with asphalt or the like. As shown in FIG. 7, a plurality of rain grooves are arranged along a traveling direction of the vehicle. There is a possibility that it will be used on special road surfaces that are arranged at a set pitch, such as those used on highways in California, which is a city in the United States. It is desirable to design the tire so that it can be used.
[0003]
In such a special road surface, the groove groove edge edge of the circumferential groove located in the center region of the tread portion of the tire is caught or fitted into the rain groove carved on the road surface, so that it is small. There is a possibility that a so-called rain groove wandering phenomenon, which is a phenomenon in which the steering wheel is removed and the running stability is lost, may occur.
[0004]
For this reason, in a conventional pneumatic tire for a motorcycle, in the center region of the tread, a circumferential groove is formed as a single straight groove, and a land portion that does not form a rib-like land portion in the region is configured. Or it is common to suppress the occurrence of rain groove wandering phenomenon by making the circumferential groove zigzag so that the edge of the groove wall of the circumferential groove is not caught by the rain groove carved on the road surface. It is.
[0005]
[Problems to be solved by the invention]
However, as motorcycles become more sophisticated in recent years, further improvements in stability during high-speed driving and shimmy performance due to resonance with the vehicle body are required. It was necessary to reduce the rigidity of the land portion located in the center region of the tread portion.
[0006]
The most effective means for achieving this is to arrange a pair of circumferential main grooves extending along the tire equator plane in the center region so as to be relatively narrow between them. It is useful to have a tread pattern with a wide rib-like land.
[0007]
Although the tire having the tread pattern is good in straight running stability during high-speed running and shimmy performance due to resonance with the vehicle body, it is easy to fit into a rain groove in which the rib-like land portion is carved on the road surface, Since the above-described rain groove wandering performance tends to deteriorate, it is necessary to improve the performance.
[0008]
An object of the present invention is a pneumatic tire for a two-wheeled motor vehicle having a tread pattern as described above, which has excellent straight running stability at high speed running, less shimmy due to resonance with the vehicle body, and improved rain groove wandering performance. To provide tires.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a pneumatic tire for a two-wheeled vehicle according to the present invention has a relatively narrow width at a tread center portion by a pair of saw-tooth or wave-shaped circumferential high-angle zigzag grooves disposed on both sides of the tire equator. In a pneumatic tire for a two-wheeled vehicle in which a zigzag land portion is formed,
The sawtooth or corrugated circumferential high-angle zigzag groove has a plurality of long high-angle portions on the circumference thereof that have an angle (θ) with respect to the tire equator that is greater than 0 ° and that is inclined at 15 ° or less. It consists of a short connecting part that connects the long high angle part,
The protruding corner apex (A) on one side of the zigzag center land portion formed by the pair of sawtooth or wavy circumferential high angle zigzag grooves and the entering corner portion on the other side of the land portion The distance (D) between the sawtooth or corrugated circumferential high-angle zigzag groove to be formed is the distance (D) between 18.5 to 25.4 mm or 45 to 55 mm. The ratio (D / P ratio) to the rain groove arrangement pitch (P) on the road surface is set in the range of 0.25 to 1.30.
[0010]
Moreover, it is preferable that at least the long high angle portion of the pair of sawtooth or wave-shaped circumferential high angle zigzag grooves is chamfered.
[0011]
Further, the distance between the apex of the projected corner and the apex of the opposite bank is such that the rain groove pitch (P) on the road surface is in the range of 18.5 to 25.4 mm. When the ratio (D / P ratio) to the arrangement pitch (P) is in the range of 0.50 to 1.30, and the rain groove arrangement pitch (P) on the traveling road surface is in the range of 45 to 55 mm, the rain groove arrangement is The ratio (D / P ratio) to the installation pitch (P) is more preferably in the range of 0.25 to 0.50.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a typical tread pattern of a pneumatic tire for a motorcycle according to the present invention, wherein 1 is a tread portion, 2 is a tire equatorial plane, 3 and 4 are circumferential high-angle zigzag grooves, and 5 is a zigzag shape. It is the center land.
[0013]
The tire having the tread pattern shown in FIG. 1 has a pair of saw-tooth or wave-shaped circumferential high-angle zigzag grooves 3 and 4 extending along the tire equatorial plane 2 in the center region of the tread portion 1. By disposing, a zigzag center land portion 5 having a relatively narrow width is formed in the tread center portion.
[0014]
The main feature of the present invention is that the sawtooth or corrugated circumferential high-angle zigzag grooves 3 and 4 are long, high-angle inclined at an angle θ with respect to the tire equator 2 of greater than 0 ° and less than 15 °. A plurality of angled portions 3a, 4a are provided on the circumference, and are composed of short connecting portions 3b, 4b connecting the long high angle portions 3a, 4a, and the pair of saw-tooth or wave-shaped circumferential high-angle zigzag grooves 3 , 4 formed on one side of the zigzag center land portion 5 and the opposite corner of the circumferential high-angle zigzag groove 4 that forms the corner on the other side of the land portion 5 The distance D to the apex B is set to a range of 0.25 to 1.30 as a ratio D / P ratio to the rain groove arrangement pitch P on the traveling road surface.
[0015]
By adopting the above configuration, the zigzag center land portion 5 is less likely to be fitted into the rain groove 10 carved on the road surface 9, and the above-described rain groove wandering performance is greatly improved. Since the rigidity of the land portion located in the center region of the portion 1 is appropriately softened, it is possible to improve both straight running stability during high speed running and shimmy performance due to resonance with the vehicle body.
[0016]
The circumferential high-angle zigzag groove is preferably a sawtooth shape as shown in FIG. 1 or a wavy shape as shown in FIG. 3, but other zigzag grooves are also preferred. It may be. Further, the protruding corner apex A located at the edges 5a, 5b of the zigzag center land portion 5 is clear if it is a saw blade, but the edge shape is curved like a wavy zigzag groove. In some cases, the projected corner apex A is not clear. In such a case, the points on the edge where each end edge of the zigzag center land portion 5 protrudes most outward in the tire width direction is defined as the projected corner apex A. (FIG. 3).
[0017]
By the way, most of the arrangement pitch P of the rain grooves 10 carved on the special road surface 9 is set in the range of 18.5 to 25.4 mm or in the range of 45 to 55 mm.
[0018]
In the present invention, in any special road surface 9, if the ratio D / P is set in the range of 0.25 to 1.30, it is conspicuous for all road surfaces 9 provided with a plurality of rain grooves 10. In the former case, the ratio D / P is preferably in the range of 0.50 to 1.30. In the latter case, the ratio D / P is more preferably in the range of 0.25 to 0.50. .
[0019]
That is, when the ratio D / P is less than 0.50 for the former and less than 0.25 for the latter, the width of the zigzag center land portion 5 becomes narrower and the land portion rigidity of the tread portion 1 becomes insufficient, resulting in poor steering stability. This is because the ratio D / P exceeds 1.30 for the former and exceeds 0.50 for the latter, and the tread land portion becomes flexible as the width of the zigzag center land portion 5 increases. This is because the effect of the vehicle is not obtained effectively, and the stability at high speed and the shimmy performance due to resonance with the vehicle body tend to deteriorate, and in addition, in the case of pneumatic tires for motorcycles, the curvature is Since it is relatively large, step wear is likely to occur.
[0020]
In addition, the reason why the circumferential high angle zigzag grooves 3 and 4 are limited to the zigzag groove is that when the straight groove is used, the edge of the zigzag center land portion 5 is completely grooved over the entire length of the ground contact length. In order to prevent such a situation from occurring, there is a tendency that a steering wheel is taken out and the steering stability is lost and the driving stability is lost, and a very dangerous state tends to occur for the driver.
[0021]
Further, the long high angle portions 3a and 4a constituting the circumferential high angle zigzag grooves 3 and 4 are disposed so as to be inclined with respect to the tire equatorial plane 2. The long high angle portions 3a and 4a are inclined. This can prevent the edge portions 5a and 5b of the zigzag center land portion 5 from being caught or fitted in the rain groove 10, thereby improving the rain groove wandering property. .
[0022]
The reason why the angle θ of the long high-angle portions 3a and 4a constituting the circumferential high-angle zigzag grooves 3 and 4 with respect to the tire equator is limited to more than 0 ° and not more than 15 ° is the above-described rain groove wandering In order to improve the performance, the larger the inclination angle θ, the better. However, in order to improve the drainage performance, on the contrary, the smaller the inclination angle θ, the better. As a result of intensive studies, it was found that both performances can be achieved at 15 ° or less.
[0023]
Further, according to the present invention, the edges 5a and 5b of the zigzag center land portion 5 are configured to be prevented from being caught or fitted into the rain groove 10. However, in this configuration as well, the zigzag center land portion 5 is prevented. It is difficult to completely eliminate the possibility that the edges 5a and 5b of the portion 5 fit into the rain groove 10.
[0024]
Therefore, in the present invention, as shown in FIGS. 2 and 4, it is preferable to provide the chamfered portion 7 at the end edges 5a and 5b of the zigzag center land portion 5, whereby the zigzag center land It is possible to further prevent the edges 5a and 5b of the portion 5 from being caught or fitted into the rain groove 10, thereby further improving the rain groove wandering property.
[0025]
The above description only shows an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.
[0026]
For example, each of the tires shown in FIGS. 1 to 4 has a pair (two) of circumferential high-angle zigzag grooves arranged in the tread portion 1. However, the present invention is not limited to this configuration. Without being limited, the number of circumferential high-angle zigzag grooves can be increased as necessary. Further, in these drawings, an inclined groove 11 extending from the short connecting portions 3b and 4b of the circumferential grooves 3 and 4 toward the outer side in the tire width direction, and 2 extending from the inclined groove 11 in a direction substantially orthogonal thereto. The auxiliary grooves 12 and 13 of the book are provided, but such grooves can be appropriately provided as necessary.
[0027]
【Example】
Next, a pneumatic tire for a motorcycle according to the present invention was prototyped and its performance was evaluated, which will be described below.
In the first and second embodiments, only the front wheel of the two-wheeled vehicle is provided with the tread pattern of the figure number shown in Table 1, the arrangement shape and number of the circumferential high angle zigzag grooves 3 and 4, and the edge of the zigzag center land portion 5. Pneumatic tires with and without chamfering and tread rigidity were mounted, and the performance was evaluated by running the motorcycle. The tire sizes were 120 / 75ZR17 for the front wheels and 180 / 55ZR17 for the rear wheels.
The other tire structures are almost the same as those of a general pneumatic tire for a motorcycle.
[0028]
For comparison, Conventional Example 1 using a tire in which only one straight circumferential main groove 14 is arranged in the center region of the tread portion and straight circumferential main grooves 15, 16 in the center region of the tread portion. Also for Conventional Example 2 using tires having two tires, the performance was evaluated by attaching the same to a two-wheeled vehicle and running the two-wheeled vehicle.
[0029]
[Table 1]
[0030]
(Test method)
Each of the above test tires is mounted on a standard rim defined by JATMA to form a tire wheel, and a tire wheel having a tire internal pressure of 2.5 kgf / cm ² for the front wheel tire and 2.9 kgf / cm ² for the rear wheel tire is used on the motorcycle. Wearing and driving by a professional driver when driving on a special road with rain grooves engraved with a pitch P of 19mm, straight running at high speed, shimmy performance, and rain groove wandering Was evaluated. Table 1 shows these evaluation results. The numerical values for performance evaluation in Table 1 are all shown as an index ratio with the conventional example 1 as 100, and the larger the value, the better.
[0031]
From the evaluation results in Table 1, both Example 1 and Example 2 are superior in straight running performance and shimmy performance during high speed running as compared with Conventional Example 1, and the conventional example of rain groove wandering is also known. Compared to 2, it was significantly improved and almost the same level as in Conventional Example 1.
[0032]
【The invention's effect】
According to the present invention, pneumatic stability for a two-wheeled vehicle is excellent in straight running stability at high speed traveling, less shimmy due to resonance with the vehicle body, and less likely to cause the rain groove wandering phenomenon when traveling on the above-mentioned special road surface. Tires can now be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a tread pattern of a pneumatic tire for a motorcycle according to the present invention.
FIG. 2 is a diagram showing another embodiment.
FIG. 3 is a diagram showing another embodiment.
FIG. 4 is a diagram showing another embodiment.
FIG. 5 is a view showing a tread pattern of a tire of Conventional Example 1;
6 is a view showing a tread pattern of a tire of Conventional Example 2. FIG.
7A and 7B show an example of a special road surface 9 in which a plurality of rain grooves 10 are engraved. FIG. 7A is a cross-sectional view, and FIG. 7B is a plan view.
[Explanation of symbols]
1 Tread
2 Tire equator
3,4 circumferential high angle zigzag groove
5 Zigzag center land
6 Tire width direction
7 Chamfer
8 Vehicle direction
9 Special road surface
10 Rain groove
11 Inclined groove
12,13 Auxiliary groove
14 ~ 16 circumferential main groove

Claims (4)

In a pneumatic tire for a two-wheeled vehicle in which a relatively narrow zigzag land portion is formed in a tread center portion by a pair of saw blade-like or wavy circumferential high-angle zigzag grooves disposed on both sides of the tire equator,
The sawtooth or corrugated circumferential high-angle zigzag groove has a plurality of long high-angle portions on the circumference that are inclined when the angle (θ) to the tire equator is greater than 0 ° and less than 15 °, and It consists of a short connecting part that connects the long high angle part,
The protruding corner apex (A) on one side of the zigzag center land portion formed by the pair of sawtooth or wavy circumferential high angle zigzag grooves, and the entering corner portion on the other side of the land portion, The distance (D) between the sawtooth or corrugated circumferential high-angle zigzag groove to be formed is the distance (D) between 18.5 to 25.4 mm or 45 to 55 mm. A pneumatic tire for a two-wheeled vehicle, wherein a ratio (D / P ratio) to a rain groove arrangement pitch (P) on a road surface is set in a range of 0.25 to 1.30.   2. The air for a motorcycle according to claim 1, wherein at least one of the long high angle portions of the pair of sawtooth or wave-shaped circumferential high-angle zigzag grooves is chamfered. Enter tire. The distance (D) between the projected corner apex (A) and the opposite bank apex (B) is set to the rain groove arrangement pitch (P) on the traveling road surface in the range of 18.5 to 25.4 mm . The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the ratio (D / P ratio) is in the range of 0.50 to 1.30. The distance (D) between the protruding corner apex (A) and the opposite bank apex (B) is a ratio (D /) to the rain groove arrangement pitch (P) on the traveling road surface in the range of 45 to 55 mm. The pneumatic tire for a two-wheeled vehicle according to claim 1 or 2 , wherein the P ratio is in the range of 0.25 to 0.50.

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