JP2001315506A - Tire for motor-tricycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the abrasion resistance of a tire for a motor-tricycle. SOLUTION: This tire for a motor-tricycle is mounted on two rear wheels of the motor-tricycle. A pair of longitudinal grooves 7 and 7 continuously extended in the tire circumferential direction at both sides of a tire equator C are formed on a tread face 2a for defining a central rib 9 located between the longitudinal grooves 7 and 7, and side parts 10 respectively formed between the longitudinal groove 7 and a tread ground end E. The central rib 9 has a width L of 15-30% of a tread ground width TW. The side part 10 is formed by a row of blocks of blocks B defined by lug groove-shaped translots 11 with one end communicated with the longitudinal groove 7 and the other end extended over the treat ground end E. A depth of the translot 11 is determined to be 5-7% of a nominal size of a sectional width of the tire, and equalized to a length from one end to the tread ground end. A radius of curvature of the tread face 2a is determined to be 75-200% of the nominal size of the cross- sectional width of the tire on a tire meridional cross-section in a load-free state with the internal pressure charged after the rim assembling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire for a motorcycle capable of improving abrasion resistance.

[0002]

2. Description of the Related Art As shown in FIG. 3, there is known a tricycle M having two wheels Rt, Rt, each having one wheel Ft in front and driven by a motor. Have been. This type of three-wheeled motor M is often used for commercial purposes such as home delivery of food, so it travels a large distance in a short period of time, and in particular, there is a problem that tires of the rear wheel Rt on the driving side are severely worn. there were.

[0003] The inventors of the present invention have investigated the shape and the like of the conventional tire used for the rear wheel Rt of this type of vehicle, and found that most of the shape of the tire for a motorcycle such as a scooter is diverted as it is. I understood. In general, a motorcycle tire turns while tilting the vehicle to give a camber angle to the tire, so that a tread surface a is formed by an arc having a small radius of curvature R as shown in FIG.

However, in the case of a motorcycle, the two tires arranged in parallel make contact with the ground, so that there is virtually no camber angle given to the tire for the rear wheel as in a motorcycle. For this reason, when the radius of curvature of the tread surface is set to be small, there is a problem that the contact area decreases, the contact pressure increases, and the wear progresses faster. Also, in conventional tires for motorcycles, the block pattern in which the tread surface is formed by blocks was the mainstream, so the rigidity of the tread surface was low and slippage was likely to occur between the tread surface and the road, and it was thought that it also caused early wear. Can be

The present invention has been devised in view of the above-described problems. The present invention provides ribs and blocks on a tread surface, appropriately regulates the dimensions of the ribs and blocks, and reduces the radius of curvature of the tread surface. An object of the present invention is to provide a tire for a motorcycle that can improve abrasion resistance on the basis of increasing the tire size.

[0006]

SUMMARY OF THE INVENTION An invention according to claim 1 of the present invention is a tire for a motorcycle mounted on two wheels behind the motorcycle, the tire being provided on a tread surface on both sides of a tire equator. By providing a pair of vertical grooves extending continuously in the tire circumferential direction, a central rib sandwiched between the vertical grooves and continuous in the tire circumferential direction, and a side portion between the vertical groove and the tread contact edge. The center rib has a width tw in the axial direction of the tire of 15 to 30% of a tread contact width, which is a distance between the tread contact ends, and one end of the side portion communicates with the vertical groove. The other end is formed of a row of blocks arranged in the circumferential direction of the tire and divided by a lateral groove extending beyond the tread contact edge, and the depth of the lateral groove is 5 to 7% of a nominal dimension of a sectional width of the tire. And from the one end The tread surface has a radius of curvature of 75 to 200% of a nominal dimension of a cross-sectional width of the tire in a tire meridian section in a no-load state in which the tire is at the same depth up to the red ground contact end and the rim is assembled and filled with internal pressure in an unloaded state. It is characterized by. Preferably, the lateral groove is bent in a V shape, a zigzag shape or a wave shape and extends to the other end side.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a development view in which a tread surface of a tire for a motorcycle (hereinafter, may be simply referred to as “tire”) according to the present embodiment is developed. FIG. The tire meridian sectional view including the tire axis in the unloaded standard state is shown. In the figure, a tire 1 according to the present embodiment includes a tread portion 2 that comes into contact with a road surface, and a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2 in the tire radial direction.
And a bead portion 4 connected to the inner end of the sidewall portion 3 and mounted on the rim J. The bead portion 4 is mounted on the two wheels Rt behind the tricycle M as shown in FIG. A tube type is illustrated.

In the tire 1, a carcass 6 extending from the tread portion 2 to the bead core 5 of the bead portion 4 through the sidewall portion 3 forms a tire skeleton. Further, the tire 1 has a tread surface 2 which is a surface of the tread portion 2.
a, a pair of longitudinal grooves 7, 7 extending continuously on both sides of the tire equator C in the circumferential direction of the tire are provided.
A central rib 9 sandwiched between the tires 7 and continuous in the tire circumferential direction, and a side portion 10 between the longitudinal groove 7 and the tread contact edge E are divided. Here, the tread grounding end E refers to a grounding end of the tread surface 2a when the tire 1 is grounded on a plane by applying a specified maximum load in the standard state. The distance between the tread contact ends E, E in the tire axial direction is defined as a tread contact width TW. The applied rim and the working internal pressure are appropriately determined according to the standard based on the tire.

In the present embodiment, the vertical groove 7 is formed as a linear groove extending symmetrically with respect to the tire equator C and continuously in the tire circumferential direction and extending linearly. However, this does not exclude the formation of a wave or a zigzag. The groove width GW1 of the vertical groove 7 is, for example, 2 to 8%, preferably 3.5 to 5.5% of the tread contact width TW.
If the groove width GW1 is less than 2% of the tread contact width TW, there is a tendency that a sufficient drainage property cannot be secured on the tire equator C side. Conversely, if it exceeds 8%, the rigidity of the tread portion 2 tends to decrease. .

The center rib 9 serves to increase the rigidity of the tread surface 2a as compared with a block divided in the circumferential direction of the tire. By arranging such a rib on the tire equator C, the tread can be efficiently formed. The rigidity of the portion 2 can be increased. The width L of the central rib 9 in the tire axial direction is set to 15 to 30%, more preferably 18 to 25% of the tread contact width TW. The width L of the central rib 9 is
If it is less than 15% of the tread contact width TW, the rigidity of the tread surface 2a tends to decrease, and if it exceeds 30%, drainage on the tire equator C side tends to decrease. The central rib 9 has a first oblique side portion 1 of a lateral groove 11 described later.
1a, the tire equator C
By forming the concave portion 13 extending to the side and terminating in front of the side, the rigidity is optimized.

One end of the side portion 10 of the tread surface 2a communicates with the vertical groove 7 and the other end thereof is connected to the tread grounding end E.
The blocks B divided by the lateral grooves 11 extending beyond are formed from a row of blocks arranged in the tire circumferential direction.

The lateral groove 11 has a width of 3 in the tire circumferential direction.
A first oblique side 11a on the tire equator side extending in the tire axial direction inclined at an angle α of 0 to 60 °, more preferably 40 to 50 °, and the first oblique side 11a is opposite to the first oblique side 11a and the tire circumferential direction. 30-60 °, more preferably 40-
And a second oblique side 11b on the side of the tread contact edge E extending at an angle β of 55 °, which are connected smoothly by a V-shaped top T. It is needless to say that the lateral groove 11 can be variously changed in place of such a V-shape, for example, bent in a smooth zig-sag shape (or a wavy shape) and extended to the other end side. Such a bent lateral groove 11 helps to increase the substantial length of the lateral groove 11 as compared with, for example, a straight groove, facilitates the enlargement of the groove area, and facilitates the side portion 1.
Drainage at 0 can be improved.

The depth of the lateral groove 11 is preferably 5 to 7% of the nominal dimension of the cross-sectional width of the tire. The “nominal dimension of the tire cross section width” is a value obtained by rounding the tire cross section width MW (shown in FIG. 2) in increments of 5 mm. For example, when the nominal is a metric size of “130/90”, 13
0 mm. If the depth of the lateral groove 11 is less than 5% of the nominal dimension of the sectional width of the tire, this type of tire travels a large distance in a short period of time and has a large amount of wear. Cannot secure a sufficient groove depth. Conversely, when the depth of the lateral groove 11 exceeds 7% of the nominal dimension of the cross-sectional width of the tire, the rigidity of the side portion 10 decreases, and the tire tends to wobble during running.

It is necessary that the horizontal groove 11 has substantially the same depth from one end on the side of the vertical groove 7 to the tread contact end E. Conventionally, the depth of the lateral groove 11 of a motorcycle tire diverted from a motorcycle tire is set to be the largest on the tread crown portion side and gradually decrease toward the tread contact edge E side. There is. However, in such a configuration, when wear progresses, the lateral groove 11 disappears first at the tread contact end E side portion where the groove depth is small, and slippage or the like is likely to occur at the time of contact at the contact end side, and further wear progresses. There is a problem of making it. In this embodiment, the abrasion resistance is further improved by making the depth of the lateral groove 11 substantially constant from the one end side to the tread contact end E side. The groove width GW2 of the lateral groove 11
Is preferably, for example, 3 to 8%, preferably 4.5 to 6.5% of the tread contact width TW. In this example, the groove width GW2 of the vertical groove 11 gradually increases from the one end to the tread contact end E. An example is shown below.

The side portion 10 has one end connected to the V-shaped top portion T of the lateral groove 11 and the other end connected to the second oblique portion 1 of the lateral groove 11 between the lateral grooves 11 adjacent in the tire circumferential direction.
A linear narrow groove 14 inclined to the tire circumferential direction is provided by being connected to a substantially intermediate position of the length of 1b. The groove width GW3 of such a narrow groove 14 is, for example, 10 to 60% of the average groove width of the lateral groove 11, and more preferably 20 to 40%.
%, And is set to about 33% in this example.
Further, the groove depth of the narrow groove 14 is 20 to 20 times the groove depth of the lateral groove 11.
It is desirable to set it to 40%. The narrow groove 14 is inclined in the same direction as the second oblique side 11b on both sides of the tire equator, but one side of the tire equator C may be reversed. Such narrow grooves 14 serve to smooth the deformation of the blocks B when the blocks B of the side portions 10 are in contact with the ground, and to further improve the wear resistance. Also, from this point of view,
The inclination angle θ of the narrow groove 14 with respect to the tire circumferential direction is:
For example, it is desirably 5 to 30 °, more preferably 10 to 20 °.

In the tire 1, as shown in FIG. 2, the radius of curvature TR of the tread surface 2a in the tire meridian section in the standard state is set to 75 to 200% of the nominal dimension of the sectional width MW of the tire. You. In the conventional motorcycle tire, the radius of curvature TR of the tread surface 2a is:
Although the tire was extremely small, for example, set to 70% or less of the nominal dimension W of the tire cross-sectional width MW, the curvature was large. However, such a tread surface 2a could not provide a sufficient contact area, and the tread center could not be obtained. The contact pressure is locally increased in the part and the wear proceeds early. In this embodiment,
The radius of curvature TR of the tread surface 2a is set to 75 to 200% of the nominal dimension of the tire cross-sectional width MW, more preferably 75 to 13%.
By setting a relatively large single radius of curvature of 0%, more preferably 80 to 100%, the contact area can be increased and the wear resistance can be effectively improved. The tread contact width TW is set to be smaller than the nominal dimension of the cross-sectional width MW of the tire, and is preferably set to 70 to 90%.

[0017]

EXAMPLE The tire size shown in FIGS.
Trial production of 0 / 90-653J motorcycle tricycle tire,
Performance was evaluated by performing a wear resistance test. In the abrasion resistance test, the test tire was mounted on the rear two wheels of a three-wheeled motor vehicle, the vehicle traveled steadily on a test course, and the amount of wear was compared based on the distance traveled. The evaluation was performed using an index with Conventional Example 1 being 100.
The higher the value, the better. Table 1 shows the test results.

[0018]

[Table 1]

As a result of the test, it was confirmed that the example of the present invention has improved wear resistance as compared with the conventional example.

[0020]

As described above, according to the first aspect of the present invention, the abrasion resistance can be suitably improved by being mounted on the two wheels behind the motorcycle.

[Brief description of the drawings]

FIG. 1 is a developed view showing a tread portion of a motorcycle tire according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a tire for a motorcycle in a standard state in which a rim is assembled and a working internal pressure is charged.

FIG. 3 is a perspective view illustrating a motorcycle.

FIG. 4 is a schematic cross-sectional view of the right half illustrating a conventional motorcycle tire.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Vertical groove 9 Central rib 10 Side part 11 Side groove

Claims (2)

[Claims] 1. A tire for a motorcycle mounted on two wheels after the motorcycle, wherein a pair of longitudinal grooves extending continuously in the tire circumferential direction on both sides of a tire equator are provided on a tread surface. A central rib sandwiched between the vertical grooves and a side portion between the vertical groove and the tread contact edge, which is continuous in the tire circumferential direction; and a center rib having a width tw in the tire axial direction. Is 15 to 30 of the tread contact width, which is the distance between the tread contact ends.
%, And the side portion is formed of a block row in which one end communicates with the vertical groove and the other end is divided by a lateral groove extending beyond the tread contact edge in a tire circumferential direction. The depth of the tire is 5 times the nominal size of the cross-sectional width of the tire.
-7% and the same depth from the one end to the tread ground contact end, and in a tire meridian section in a no-load state in which the rim is assembled and filled with internal pressure, the radius of curvature of the tread surface is the nominal sectional width of the tire. A tire for a motorcycle, which is 75 to 200% of the size. 2. The tire for a motorcycle according to claim 1, wherein the lateral groove is bent in a V-shape, a zig-sag shape or a wave shape and extends to the other end side.