JP3273736B2 - Motorcycle tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a motorcycle tire capable of improving cornering performance on ice.

[0002]

2. Description of the Related Art Since the use of spiked tires has been banned to prevent road surface damage and dust pollution, pneumatic tires called so-called studless tires have become widespread in multiple snow areas. .

[0003] This type of tire is inferior in running performance especially on ice compared to a spiked tire. Therefore, various proposals have conventionally been made for improving running performance on ice.

For example, Japanese Patent Laying-Open No. 3-38413 proposes providing a plurality of sipes extending in the tire axial direction in a block defined on a tread surface. This proposal presupposes a studless tire for a four-wheeled vehicle that emphasizes braking performance especially on ice.

However, unlike a four-wheeled motor vehicle, a motorcycle turns by giving a camber angle to a tire by inclining the vehicle. Therefore, merely providing an axially extending siping on a tire block as described above requires When the vehicle is tilted, skidding tends to occur, and the vehicle can easily fall over, so that satisfactory cornering performance on ice cannot be secured.

On the other hand, Japanese Patent Application Laid-Open No. 5-58116 discloses a motorcycle tire having a contact area of 100 cm.
² per by identifying the total length in the tire circumferential direction component of the sipes in 60～90Cm, proposes to improve the耐横slip performance in ice.

[0007]

However, Japanese Patent Application Laid-Open No. 5-58116 evaluates the cornering performance of motorcycle tires on ice in consideration of the influence of the tire circumferential component of siping. Although it is possible, it is still a proposal focusing on braking performance on ice, and cornering performance on ice has not been sufficiently evaluated in actual vehicles.

The present inventors have disclosed in Japanese Patent Application Laid-Open No. 5-58116.
In a cornering test on ice using tires as disclosed in Japanese Patent Application Laid-Open No. H10-209, it was confirmed that there was still a problem that satisfactory cornering performance could not be obtained on slippery ice called ice burn.

The inventor of the present invention has considered that in a motorcycle that performs cornering by inclining the vehicle, if the motorcycle slides over ice and falls over, the length of the circumferential component of the siping and the axial component are reduced. By focusing on this ratio and increasing the circumferential component compared to conventional siping, it has been found that skidding on ice can be suppressed and cornering performance on ice can be improved.

[0010] As described above, an object of the present invention is to improve cornering performance on ice in a motorcycle tire requiring a different kinetic performance than a four-wheeled vehicle.

Another object of the present invention is to improve steering stability on a dry pavement road.

[0012]

According to the first aspect of the present invention, a plurality of main grooves extending in the circumferential direction of the tire and sub-grooves connecting the main grooves are provided on the outer surface of the tread portion. Forming a plurality of blocks surrounded by the main groove and the sub-groove, assembling the tire into a regular rim, applying a standard maximum internal pressure and a standard maximum load, and having a camber angle of 0 °.
In the block in the contact area contacted with the ground, while providing a siping group consisting of a plurality of sipes arranged side by side with a small gap, a circumferential siping group consisting of a circumferential siping extending substantially along the tire circumferential direction. And a block having an inclined siping group composed of a siping inclined with respect to the tire circumferential direction are provided alternately in the tire circumferential direction, and the total length of the circumferential components of the siping in the contact area ( The ratio (ΣWi / ΣLi) between (ΣLi) and the total length of the axial components (ΣWi) is 0.2 or less.
Upper and 1.4 or less , and the siping has both ends
A tire for a motorcycle, which is a closed type terminating in a block .

According to a second aspect of the present invention, in the grounding state, the tread portion is a real ground which is a sum of a total length of siping in the ground region (ΣRLi) and a block area in the ground region. The ratio (ΣRLi / SS) to the total ground area (SS) obtained by adding the groove area (SG) occupied by the main groove and the sub-groove in the ground area to the area (SL) is 0.05 or more and 0.5 or less. And the actual contact area (SL)
And the ratio (SL / SS) of the total ground area (SS) to 0.4 or more and 0.8 or less.

[0014] Further, the invention according to claim 3 is characterized in that the block includes a siping block having a circumferential siping group consisting of a circumferential siping extending substantially along the tire circumferential direction.

Here, "motorcycle tire" includes:
"Motorized bicycle tires" are also included.

The above "inside contact area" means the outermost end in the axial direction of the tire when the tire is assembled on a regular rim, a standard maximum internal pressure and a standard maximum load are applied, and the tire is grounded at a camber angle of 0 °. It is defined as the entire area included between positions, and the standard conforms to JATMA.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an internal structure of a motorcycle tire, and FIG. 2 shows a developed tread pattern.

In the present embodiment, the tire for a motorcycle is
Bead section 4 from tread section 2 through sidewall section 3
An example of a winter studless tire having a carcass 6 that folds the bead core 5 around is shown.

In the present embodiment, the carcass 6 is formed by stacking two carcass plies 6A and 6B in which nylon cords are arranged at an angle of 43 ° with respect to the tire equator C in a direction in which the cords cross each other. 9 illustrates a combined bias structure. It should be noted that an organic fiber cord such as polyester or rayon may be appropriately used as the carcass cord.

The outer surface 2A of the tread portion 2 extends in an arch shape from the tire equator C toward the tread edges E, E on both sides in the tire axial direction, and extends in the tire axial direction between the tread edges E, E. The tread width TW, which is the distance, is configured to be substantially equal to the tire maximum width. Therefore, when the camber angle is given, the motorcycle tire can effectively contact the outer surface 2A of the tread portion 2 to generate a camber thrust necessary for cornering.

The outer surface 2A of the tread portion 2 is provided with a plurality of main grooves 7 extending in the circumferential direction of the tire and sub-grooves 9 connecting the main grooves 7, 7, so that the main grooves 7, the sub-grooves are provided. A plurality of blocks 10 surrounded by 9 are formed.

In the present embodiment, the main groove 7 comprises a first main groove 7a extending parallel to the tire circumferential direction and a second main groove 7b extending obliquely to the tire circumferential direction. In the present embodiment, the sub-groove 9 has a substantially V-shape extending from the tire equator C toward the tread edges E on both sides.

In the present embodiment, by providing such a main groove 7 and a sub groove 9, a so-called symmetrical directional pattern is formed on the outer surface 2A of the tread portion 2. For example, the sub groove 9 is formed in the tire axial direction. The motorcycle is mounted on the motorcycle in such a way that it touches the ground sequentially from the end of the tire and finally touches the tire equator side. Thereby, the motorcycle tire is preferable in that the V-shaped portion of the sub-groove 9 at the tire equator effectively exerts an effect of shaving the road surface and can enhance traction on snowy roads and icy roads.

The main grooves 7a and 7b and the sub groove 9 are
In any case, the groove width and the groove depth can be appropriately determined according to the conventional example. For example, the groove width is 2.5 to 7.0 mm and the groove depth is 3.0 to 3.0.
11.0 mm, and in this example, 8 mm.

By arranging the main groove 7 and the sub-groove 9, the block 10 is provided between the first main grooves 7a, 7a, for example, as shown in FIG. The roof blade-shaped block 10a is located between the first main grooves 7a, 7a.
a, a rectangular block 10c provided along the tread edge E,
A plurality of shapes such as a trapezoidal block 10d provided between the second main grooves 7a and 7b and arranged on both sides of the tire equator C are defined (hereinafter, simply referred to as a block 10).

Next, a motorcycle tire is manufactured by JATMA.
A small gap is provided in the block 10 in the contact area (width: PW) where the rim is assembled to the regular rim specified by the standard and the standard maximum internal pressure and the standard maximum load are applied, and the camber angle is 0 ° and the ground is grounded. A siping group 12 including a plurality of sipings 11 arranged side by side is provided.

In the present embodiment, the siping group 12 is
Eight sipes 11 are arranged in parallel with a small gap of about 2 mm so as to prevent chipping of the rubber, and both ends of the sipes 11 are terminated inside the block .
Rosed sipe.

In the siping 11, a circumferential siping group 12a consisting of a circumferential siping 11a extending linearly substantially along the tire circumferential direction is provided in the arrow-shaped block 10a and the diamond-shaped block 10b. An inclined siping group 12b composed of sipes 11b inclined at about 28 ° with respect to the tire circumferential direction and extending in a straight line is provided in the trapezoidal block 10d.

Then, these circumferential siping groups 1
Blocks 10a and 10b provided with 2a and blocks 10d and 10b provided with an inclined siping group 12b.
e are provided alternately in the tire circumferential direction .

Here, "the siping extends substantially along the tire circumferential direction" means that the siping is within a range of ± 5 ° with respect to the tire circumferential line. Further, “the siping extends inclining in the tire circumferential direction” refers to a case in which the siping inclines at an angle of more than 5 ° with respect to the tire circumferential direction.

As described above, by providing the siping group 12 in the block in the contact area, the edge of the siping 11 can increase the frictional force with the road surface.
It can improve running performance on ice.

The "inside contact area" is defined as the entire area of the tire included between the outermost end positions P, P in the tire axial direction of the tire contact area S shown in FIG. The ratio (ΣWi / ΣLi) of the total length (ΣLi) of the circumferential components of the siping 11 in the contact area to the total length (ΣWi) of the axial components is about 0.2 or more and 1.4 or less. In this example, it is set to about 0.2.

As described above, by making the ratio (ΣWi / ΣLi) of the total length (ΣLi) of the circumferential components of the siping and the total length (ΣWi) of the axial components smaller than in the conventional case, the relative length can be relatively reduced. The total length (ΣLi) of the circumferential components of the siping can be increased.

Therefore, in the motorcycle tire of the present invention, since the circumferential component of the siping 11 in the contact area can increase the road surface frictional force at the time of cornering of the motorcycle, side slip on ice can be suppressed, Cornering performance on ice can be improved.

The blocks 10a and 10b provided with the circumferential siping groups 12a and the blocks 10d and 10e provided with the inclined siping groups 12b are provided alternately in the tire circumferential direction. ,
Since the tire circumferential component of the siping can be uniformly contacted with the road surface during one rotation of the tire,
Furthermore, it can contribute to improving cornering performance on ice.

Here, as shown in FIG. 3, the total length of the tire circumferential direction components ΣLi and the total length of the tire axial components ΣWi of the sipes in the contact area are, as shown in FIG. The length L1 of the directional component,
.. And the axial components W1, W2, W3,.

If the ratio (ΣWi / ΣLi) of the total length (ΣLi) of the circumferential components of the siping and the total length (ΣWi) of the axial components exceeds 1.4, the contact area within the contact area will be lost. Since the circumferential component of the siping 11 is reduced, the effect of suppressing the side slip on ice cannot be exhibited yet.

Preferably, the ratio (ΣWi / ΣLi)
It is desirable to increase the circumferential component of the siping to 1.0 or less, more preferably 0.6 or less, since the effect of preventing sideslip during cornering is further enhanced.
No.

The reason why the camber angle is defined as 0 ° in the contact area is that the camber angle can be suppressed smaller when turning on ice than when turning on a dry pavement.

The siping 11 has a groove width of 0.3 to
It is desirable that the thickness be 2.0 mm, more preferably 0.3 to 1.0 mm. If the groove width of the siping is less than 0.3 mm, it becomes difficult to manufacture a knife blade of a mold.
When the lateral force is applied, when the lateral force acts on the block, the effect of securing the block rigidity by closing the siping 11 is inferior, and the steering stability on the dry pavement tends to decrease.

It is desirable that the depth of the siping 11 is 30 to 100% of the maximum depth of the main groove 7 or the sub groove 9. If the depth of the siping 11 is less than 30% of the maximum depth of the main groove 7 or the sub-groove 9, the edge effect of the siping 11 tends not to be sufficiently exerted. 9 above 100% of the maximum depth, siping 11
The thickness of the rubber gauge on the inner side in the tire radial direction becomes thin, and cracks easily occur at the bottom of the siping.

In this embodiment of the winter tire, a platform having a depth of 50% of the depth of the main groove is provided as a guide that can guarantee the performance on snow. Therefore, it is necessary to exert the edge effect of the siping 11 up to the time of 50% wear of the main groove depth. Therefore, the depth of the siping 11 in this embodiment is 4.0 mm, which is 50% of the main groove depth of 8.0 mm.

Therefore, the depth of the siping 11 is
Alternatively, 40% or more of the maximum groove depth of the sub-groove 9 is more preferable. If the depth of the siping 11 is too deep, the rigidity of the block is reduced, and the maneuverability on a dry pavement road is liable to deteriorate. Therefore, the depth of the siping 11 is 7 times the groove depth.
0% or less is more preferable.

The siping 11 may be a fully open type in which both ends communicate with the main groove 7 or the sub-groove 9, but in this case, the steering stability on a dry pavement is reduced due to a decrease in block rigidity. Because of the tendency to decrease, it is preferable to use a semi-open type in which one end ends in the block, and more preferably a closed type as in the present embodiment.

Note that the number of sipings, the small gaps, and the like can be appropriately changed according to the size of the block, and are not limited to the above example.

Next, in the present embodiment, the tread portion 2
In the grounded state, the main groove and the sub-groove in the ground region occupy the total ground length (ＳＬRLi) of the siping in the ground region and the actual ground area (SL) which is the sum of the areas of the blocks in the ground region. Total contact area (S) including groove area (SG)
S) and the ratio (ΔRLi / SS) is 0.05 or more and 0.1.
5 or less.

This ratio (ΣRLi / SS) represents the siping length per unit area in the unit contact area, and is 0.05%.
If the number is less than 0.5, the number or length of the sipings tends to be insufficient and the performance on ice tends to decrease. Conversely, if the number exceeds 0.5, the number or length of the sipings becomes excessive and the block rigidity is reduced. There is a tendency.

From such a viewpoint, it is preferable that the ratio (ＳＳRLi / SS) is not less than 0.08 and not more than 0.2. The total length of siping (ピ ン グ RL
As shown in FIG. 3, i) is obtained by measuring the actual length (for example, RL5) of each siping and summing the measured values.

Also, as in the present embodiment, it is necessary to improve running performance on snow in tires for running on icy and snowy roads (studless tires, snow tires, etc.). Contact area (S
L) and the ratio (SL / S) of the total contact area (SS).
S) It is desirable that the so-called land ratio is 0.4 or more and 0.8 or less.

When the land ratio is less than 0.4, the actual contact area (SL), that is, the area of the land (block) is reduced, so that the wear resistance and the steering stability on a normal dry pavement are reduced. It tends to decrease.

When the land ratio exceeds 0.8, the area of the sea (groove) decreases, and when traveling on snow,
As a result of reducing the amount of snow pillars caused by compacting the snow, the snow tends to be slippery, which tends to reduce the ability to travel on snowy roads.

From such a viewpoint, the ratio (SL / S
S) is preferably 0.5 or more and 0.65 or less. Note that it is preferable that the land ratio be the same as the above even in the shoulder region outside the tire axial direction in the contact area.

The tread portion 2 has a hardness of -5 ° C. for the tread rubber disposed outside the carcass 6 in the tire radial direction.
It is preferable that the material can maintain a hardness of 59 degrees or more and 68 degrees or less in JISA hardness at the above temperature.

In order to further improve the performance on ice, the tread portion 2 has, for example, a ratio (PW / TW) between a tread width TW (= maximum tire width) and a width PW in the contact area.
Is preferably set to be 0.5 or more, and more preferably, the ratio (PW / TW) is set to 0.6 to 0.9, more preferably 0.6 to 0.8.

If the ratio (PW / TW) exceeds 0.8, the contour of the buttress portion connected from the axially outer end of the contact area to the sidewall portion tends to be formed with a small radius of curvature, Driving stability on dry pavement tends to decrease.

Further, in relation to the contact area of the tread portion 2, the tread radius of curvature R of the contact area is determined by the tread width T.
It is desirable that the ratio to W (R / TW) be 0.5 to 1.5.

If the ratio (R / TW) is less than 0.5, it tends to be impossible to secure a sufficient contact area, and the performance on ice tends to decrease.
When W) exceeds 1.5, it becomes difficult to smoothly tilt the vehicle when turning on a dry pavement road or the like,
There is a tendency that it is difficult to obtain a camber angle required for turning.

The motorcycle tire of the present invention may be mounted on either or both of the front and rear wheels of the vehicle, and may be further configured as a radial tire having a radial carcass and a belt layer. sell.

[0059]

[Example] Tire size 2.75-14 (rim size:
1 × 14 × WM 1.60, internal pressure 1.75 kgf / cm ² ), a conventional tire having the structure shown in FIG. 1 and the tread pattern shown in FIG.
The tires 1 to 4 as products and the tire 5 as an example product were prototyped, and the performance was tested using a motorcycle with a displacement of 90 cc. The structure of the tire and the test method are shown in Table 1 and below.

[0060]

[Table 1]

Tire structure ・ Carcass Number of carcass plies: 2 Cord: Nylon (840d / 2) Cord angle: 43 ° to the equator of the tire (cross ply) ・ No belt ・ Sipe width: 0.5mm ・ Sipe depth Length: 4.0mm-Depth of main groove and sub groove: 8mm

Test Method a) Cornering performance on ice The vehicle was run around a slippery icy road on a test course, and the conventional driver was evaluated by a five-point method of 3.0 based on the feeling of a test driver. The larger the value, the better the cornering performance on ice.

B) Braking performance on ice In general, when the motorcycle is running on an icy road, braking is performed with the rear wheel brake (because the front wheel tires slip and roll over easily when the front wheel brake is applied). Therefore,
In this test, a speedometer, braking distance measurement and test tires were attached to the test vehicle, and the vehicle was driven at a constant speed of 30 km / H on the slippery test road surface formed by the ice floe.
The rear wheel lock brake was applied, and the braking distance until the vehicle stopped was measured. The evaluation was performed using an index with the average braking distance of five times that the vehicle could be stopped without rolling over as a conventional example as 100.
The larger the value, the better the braking performance on ice.

C) Stable braking performance on ice The five-point method (3.0 in the conventional example) is used to determine the number of falls and the stability during braking in the braking test on ice described in b) above by the driver's feeling. And evaluated. Table 2 shows the test results.

[0065]

[Table 2]

As is clear from the results of Test Example 9 , when the tire of the present invention was used for the front and rear wheels of a motorcycle,
Although the braking distance on ice is slightly inferior to that of the conventional tire, the cornering (turning) performance on ice is particularly excellent, and the behavior of the vehicle at the time of braking is stable, and it can be confirmed that the safety is greatly improved. .

Further, when the tire of the present invention is used only for the front wheel of a motorcycle and the tire of the prior art is used for the rear wheel ,
Is preferable in that the braking distance can be reduced while the above-described effect is achieved.

From such a viewpoint, the tire according to the present invention (the ratio (ΣWi / ΣLi) is 0 to 1.
4) a tire pair for a motorcycle, wherein the ratio (ΣWi / ΣLi) is greater than 1.4, preferably 1.5 or more, more preferably 2.7 or more on the rear wheel. It is desirable to do.

[0069]

As described above, the motorcycle tire of the present invention has a ratio (ΣWi / ΣL) of the total length of the circumferential components of the siping (サ イ Li) to the total length of the axial components (ΣWi).
By regulating i), the total length (ΣLi) of the circumferential components of the siping can be relatively increased as compared with the related art, so that the circumferential components of the siping in the contact area are controlled by the cornering of the motorcycle. The road surface frictional force at the time can be increased, side skid on ice can be suppressed, and cornering performance on ice can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a development view showing the tread pattern in a developed manner.

FIG. 3 is an enlarged plan view of a block.

FIG. 4 is a development view showing a tread pattern of a conventional example in a developed manner, and FIGS.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Main groove 9 Sub groove 10 Block 11 Siping 12 Siping group C Tire equator

Claims (3)

(57) [Claims] 1. A plurality of blocks surrounded by the main groove and the sub groove are formed on the outer surface of the tread portion by providing a plurality of main grooves extending in a tire circumferential direction and a sub groove connecting the main grooves. It consists of a plurality of sipes lined up with small gaps in a block in the contact area where the tire is assembled on the regular rim, the specified maximum internal pressure and the specified maximum load are applied, and the tire is grounded at a camber angle of 0 °. While providing a siping group, a block having a circumferential siping group consisting of a circumferential siping extending substantially along the tire circumferential direction, and a block having an inclined siping group consisting of a siping inclined relative to the tire circumferential direction. The total length of the circumferential component of the siping (ΣLi) and the total length of the axial component (ΣWi) of the siping in the contact area are alternately provided in the tire circumferential direction. The ratio (ΣWi / ΣLi) was 0.2 or more and 1.4 or less, and the sipes, click with both ends terminating within the block
Motorcycle tire characterized by being of the rose type . 2. The tread portion has a total length (サ イ RLi) of siping in a ground area in the ground state.
And the total ground area (SS) obtained by adding the groove area (SG) occupied by the main groove and the sub-groove in the ground area to the actual ground area (SL) which is the sum of the areas of the blocks in the ground area (領域 RLi
/ SS) is not less than 0.05 and not more than 0.5, and the ratio (SL / SS) of the actual contact area (SL) to the total contact area (SS) is 0.4 or more and 0.1. 8
The motorcycle tire according to claim 1, wherein: 3. The motorcycle tire according to claim 1, wherein the block includes a sipe-containing block having a circumferential sipe group including a circumferential sipe extending substantially along the tire circumferential direction.