JPH11245627A - Tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise at the time of acceleration running while running performance over an irregular ground is being maintained, and to make a tire optimum as a tire for the driving wheel (rear wheel side) of an motor cycle to be used for both the irregular ground and the normal ground in particular. SOLUTION: In a ground contacting area 2A in an upright condition, a land ratio T/S is 0.35 to 0.5. In each block B within the ground contacting area 2A, a block periphery 6p at the first contacting side is inclined to the later contacting side by the angle α of 20 deg. to 40 deg., and the angle θd of a wall surface 7d at the later contacting side, is larger than the angle θp of a wall surface at a first contacting side. Each block B1 at the center over the equator CO of a tire and blocks B2 alternately formed into a pair while a longitudinal groove portion 5 over the equator CO of the tire is being held in between, are inclined in the ground contacting area. The groove width GW of the longitudinal groove portion 5 is 15 to 30% of ground contacting width TW, and the block peripheries 6p and 6d at the first and later contacting sides in the center block B1, are formed into a V shape inclined to the later contacting side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can reduce noise during acceleration running while maintaining running performance on uneven terrain, and is particularly suitable as a driving wheel side (rear wheel side) tire for a motorcycle that is also used for uneven terrain. The present invention relates to a motorcycle tire.

[0002]

2. Description of the Related Art In a motorcycle tire that is also used on uneven terrain, in order to ensure good running performance (traction performance) on uneven terrain, a land ratio (a block occupying a ground contact area) is required. Block patterns having a reduced surface area ratio and a large groove depth are widely used.

[0003] On the other hand, from the viewpoint of environmental protection, in recent years, there has been a strong demand for motorcycles to reduce acceleration running noise in addition to steady running noise. For this purpose, it is necessary to reduce tire noise accordingly. It is. Conventionally, for tire noise, a study has been made based on a so-called coasting noise test that measures passing noise during coasting without applying a driving force.For example, in the case of the block pattern tire, Noise reduction is achieved by changing the arrangement of blocks by the land ratio, groove depth, block size, or pitch variation method to make white noise.

[0004] However, the above-mentioned means has a problem that noise during acceleration traveling cannot be sufficiently improved, and traveling performance on uneven terrain is hindered.

[0005] Recent research has shown that the acceleration running noise is largely related to the slippage between the rear arrival side portion a1 of the block a and the road surface b caused by the driving force during acceleration, as shown in FIG. It has been found out.

Accordingly, the present invention specifies a land ratio, an inclination angle of a first block edge with respect to a tire axial direction line, an inclination angle of a first block wall surface and a second block block wall surface, and a block arrangement near the tire equator. The aim is to provide motorcycle tires that can effectively reduce acceleration running noise while maintaining high running performance on uneven terrain by combining these organically and providing a synergistic effect. I have.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a motorcycle tire having a block pattern in which a block surrounded by a groove is formed, the tire being mounted on a normal rim and having a normal internal pressure and a normal load. Is added, the ratio T / S of the area sum T of the surface of the block in the contact width area to the area S of the contact width area in the tire upright state in the tire upright state is set to 0.35 to 0, 5, and The block edge on the first arrival side of the block in the ground contact width region is inclined toward the rear arrival side outward in the tire axial direction and has an angle α of 20 to 40 ° with respect to the tire axial direction line. The wall surface connected to the block edge is inclined toward the groove bottom toward the rear arrival side, and its angle θd with respect to the tire radius line is set to be equal to or more than the angle θp of the wall surface connected with the first arrival block edge with respect to the tire radius line, The block includes a central block disposed on the tire equator, and a pair of blocks sandwiching a longitudinal groove portion on the tire equator formed alternately with the central block, and the longitudinal groove portion. The width of the groove GW is 15% to 30% of the contact width TW, and the central block is a directional block in which the edge of the block on the rear side as well as the edge of the rear side is inclined toward the rear side in the axial direction of the tire. It is characterized by being.

[0008] From the standpoint of running on uneven terrain and accelerating running noise, in particular, the angle θd on the rear arrival side and the angle θp on the first arrival side are in the range of 5 to 20 ° and 0 to 10 °, respectively, and θd > Θp is preferable.

[0009] From the same viewpoint, it is preferable that two pairs of the blocks sandwiching the vertical groove portion are juxtaposed in the tire circumferential direction along the vertical groove portion.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a motorcycle tire 1 (hereinafter referred to as a tire 1) is, in this example, a rear tire for a motorcycle that is also used on uneven terrain, and includes a tread portion 2.
Has a block pattern composed of blocks B whose periphery is surrounded by the grooves 3.

Here, in the tire 1 of the present application, when the tread portion 2 is divided into a contact width region 2A on the tire equator side and shoulder regions 2B, 2B at both ends thereof, a land ratio T in the contact width region 2A is obtained. / S is 0.35-0.
It is necessary that the range be at least 50. This is because if the land ratio T / S is less than 0.35, the minimum straight running stability required on a good road (paved road), particularly the grip property, cannot be secured, for example, the ground contact area becomes too small. On the other hand, if it is larger than 0.5, it is difficult to improve traction on uneven terrain to a satisfactory level.

The contact width region 2A is a width region where the tread portion 2 can contact the ground when the tire is mounted on a normal rim and a normal internal pressure and a normal load are applied to the tire in an upright state. The rim, the normal internal pressure, and the normal load mean a load corresponding to the standard rim, the maximum air pressure, and the maximum load capacity specified by JATMA. The land ratio T / S is determined by the total area S of the ground width region 2A.
To the area sum T of the surface of the block B in the ground width region 2A.

Next, in the block pattern, on the tire equator CO, the central block B1 and the vertical groove portions 5 are alternately arranged, and the vertical groove portions 5 are provided on both sides of the vertical groove portions 5. A pair of left and right blocks B2, B2 to be sandwiched are arranged. In this example, on both sides of the vertical groove portion 5, two pairs of blocks B2 along the vertical groove portion 5 are juxtaposed in the tire circumferential direction. It should be noted that a pair of left and right blocks B2, B2
May have different shapes from each other.

In other words, the contact width region 2A is composed of a block row R1 composed of a central block B1 arranged in the circumferential direction on the tire equator CO, and a block B2 arranged outside the block row R1 and arranged in the circumferential direction. Block row R2,
R2, a central block B1 and a side block B2.
Are arranged alternately in the circumferential direction, and in this example, the central block B1 and the two pairs of blocks B2 are alternately arranged.

The groove width GW of the vertical groove portion 5 is regulated within a range of 15 to 30% of the contact width TW of the contact width region 2A. As a result, the block B2 on the side forms an overlap portion Y in which the inner edge portion in the tire axial direction extends beyond the outer edge portion in the tire axial direction of the central block B1 and enters the tire equator side. In this example, the block B2 on the side extends over the ground width region 2A and the shoulder region 2B. However, the entire block B2 on this side may exist in the ground width region 2A. it can.

A block B arranged in the contact width region 2A,
In this example, in the blocks B1 and B2, the block edge 6 on the first arrival side of the block B that contacts the ground when the tire rolls.
p is inclined toward the rear arrival side outward in the tire axial direction, and the inclination angle α formed with respect to the tire axial line is in the range of 20 to 40 °.

In particular, in the present application, the central block B1
Is a substantially V-shaped directional block in which the rear-side block edge 6d is inclined outward toward the rear side in the tire axial direction along with the first-side block edge 6p. Block B on the other side
2 also inclines the block edge 6d on the subsequent arrival side substantially parallel to the block edge 6p on the first arrival side.

As shown in FIG. 2, each block B1, B
In 2, the first-arrival wall surface 7p connected to the block edge 6p is inclined toward the first groove side toward the groove bottom, and the second-arrival wall surface 7d connected to the block edge 6d is shifted toward the second groove wall. Lean on. Then, the angle θd of the rear arrival side wall surface 7d with respect to the tire radius line is determined by the first arrival side wall surface 7d.
The angle p is equal to or larger than the angle θp with respect to the tire radial line.

As described above, the arrangement of the blocks B1 and B2 arranged in the contact width region 2A, the inclination direction and the angle α of the first and second arrival block edges 6p and 6d, and the first and second arrival wall surfaces By regulating the angles θp and θp of the 7p and 7d, they are organically combined to produce a synergistic effect, so that the acceleration traveling noise can be reduced while maintaining high traveling performance on uneven terrain.

This effect is presumed to be achieved for the following reasons. That is, the central block B1 and the side block B2 are alternately arranged and the central block B1 is arranged.
Are V-shaped. Therefore, especially in the vicinity of the tire equator CO where the contact pressure is high, the shearing force from the biting soil can be increased, and the traction on uneven terrain can be effectively improved within a limited land ratio.

On the other hand, it is considered that the acceleration running noise is caused by the slippage of the rear arrival side portion of the block with the road surface as described above. In this regard, the block shape and arrangement described above are such that the block edge 6d on the rear arrival side is inclined to the rear arrival side, so that the entire block edge 6d does not slip instantaneously, and the sliding area at the time of kicking is reduced by the block edge 6d. Is reduced to the outer portion in the axial direction of the tire, and the contact pressure in this sliding area is reduced because the tire is separated from the tire equator CO. Therefore, acceleration running noise is suppressed.

If the angle α is less than 20 degrees, the slip range is not sufficiently reduced, and the effect of reducing the acceleration running noise is inferior. In addition, the noise performance in the steady running such as the impact sound at the time of stepping is deteriorated. If the angle α exceeds 40 degrees, the circumferential component of the shearing force received from the road surface becomes too small, and the traction on uneven terrain is significantly reduced.

The vertical groove portion 5 has a groove width GW of 0.15.
When it is less than × TW, the traction, drainage, and soil removal on uneven terrain are impaired. On the other hand, when it exceeds 0.30 × TW, the noise performance during steady running and the like deteriorates.

The first and second arrival side walls 7p, 7p
By increasing the angles θp and θp of d, the block rigidity in the circumferential direction can be improved, and slip with the road surface can be reduced. However, the first-arrival angle θp has a higher contribution to the reduction of traction on uneven terrain, but a lower contribution to the prevention of block slippage, compared to the later-arrival angle θd. Therefore, θd ≧
By setting it to θp, the rigidity of the block on the rear arrival side is relatively increased, and the slip of the block is effectively prevented while suppressing the reduction in traction, and the acceleration noise is reduced. Preferably, the angle θp of the first arrival side is set to 0 to 10 which is almost the same
゜, while maintaining traction, the angle θ
It is preferable that d is increased to 5 to 20 ° and larger than the angle θp to increase the rigidity of the block on the rear arrival side.

The shoulder region 2B is a region that comes into contact with the ground when the vehicle is turning with a camber angle.
Therefore, compared to the straight running in which the tire is in the upright state,
The frequency is extremely low, and the acceleration amount is also small. Therefore, the shape, size, and the like of the block B can be set with emphasis on running performance on uneven terrain and turning performance on a good road.

In the present embodiment, the shoulder area 2B includes an outer block B adjacent to the central block B1.
3 and a block row R4 consisting of end blocks B4 along the tread edge. In this example, the blocks B3 and B4 in the shoulder region 2B are smaller in size than the blocks B1 and B2 in the contact width region 2A, and the land ratio in the shoulder region 2B is smaller than the land ratio in the contact width region 2A. Is set to

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Tires having a bias structure (tire sands 4.60-18) having various tread patterns shown in FIGS.
The motorcycle was mounted on the rear wheel of a motorcycle dedicated to 0 cc (4 cycles) on rough terrain, and the acceleration running noise performance and the rough running performance were compared.

Accelerated running noise performance: Measured in accordance with TRIAS 20 (specified in road transport vehicle safety standards).
At the time of measurement, the front wheel of the motorcycle had a tire size of 3.00.
-21 smooth tires (slick tires without patterns) are installed. -Uneven terrain running performance: Drivability, braking performance, cornering characteristics, and the like when running on an uneven terrain test course were evaluated according to the driver's sensuality. The higher the value, the better.

[0029]

[Table 1]

[0030]

Since the motorcycle tire of the present invention is constructed as described above, it is possible to reduce the acceleration running noise while maintaining the running performance on uneven terrain, and particularly to drive a motorcycle which is also used for uneven terrain. It can be suitably adopted as a wheel side (rear wheel side) tire.

[Brief description of the drawings]

FIG. 1 is a developed view showing a block pattern of a tire according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an inclination angle of a wall surface of the block.

FIG. 3 is a development view showing block patterns of tires of Examples 3 and 4 used in the running test of Table 1.

4 (A) to (E) are developed views showing block patterns of tires of Comparative Examples 1 to 5 used in the running test of Table 1. FIG.

FIG. 5 is a cross-sectional view of a tire for explaining acceleration running noise.

[Explanation of symbols]

 2A Ground width area 3 Groove 5 Vertical groove portion 6p First-arrival block edge 6d Late-arrival block edge 7p First-arrival wall surface 7d Late-arrival wall surface B block B1 Central block B2 side block CO Tire equator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B60C 11/08 D

Claims (3)

[Claims] 1. A motorcycle tire having a block pattern in which a block surrounded by a groove is formed, wherein the tire is mounted on a regular rim and has a normal inner pressure and a regular load. The ratio T / S of the area sum T of the surface of the block in the grounding width region to the area S of the grounding width region is set to 0.35 to 0, 5, and the block edge on the first-arrival side of the block in the grounding width region is
The angle α that is inclined to the rear arrival side outward in the tire axial direction and made with respect to the tire axial direction line is set to 20 to 40 °, and the wall surface that continues to the block edge on the rear arrival side is rearward toward the groove bottom. Angle θd with respect to the tire radius line,
An angle θp or more with respect to the tire radial line of a wall surface connected to the edge of the block on the first arrival side is set to be equal to or more than a central block disposed on the tire equator and a vertical groove on the tire equator formed alternately with the central block. And a pair of blocks sandwiching the portion, and the groove width GW of the vertical groove portion is 15 to 3 with respect to the ground width TW.
0%, and the central block is a directional block in which the block edge on the rear side as well as the front side is inclined toward the rear side toward the outside in the tire axial direction. 2. The angle θd of the wall surface connected to the rear edge block edge to the tire radius line is 5 to 20 °, and the angle θp of the wall surface connected to the first arrival block edge to the tire radius line is 0 to 10 °. 2. The motorcycle tire according to claim 1, wherein the angle θd of the rear wall surface is larger than an angle θp of the first wall surface. 3. 3. The motorcycle tire according to claim 1, wherein two pairs of the blocks sandwiching the longitudinal groove portion are juxtaposed in the tire circumferential direction along the longitudinal groove portion.