JPH09109615A - Pneumatic tire for motor cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve various performance by gradually decreasing the inclina tion in relation to the tread periphery of a curved line connecting the width centers of a first main groove and a second main groove at the specified posi tion in the specified range, making the block edge and the sipe edge into the length in the specified range, and setting the negative ratio of the tread and the specified % modulus of the tread rubber into the specified range. SOLUTION: The inclinations θ1 , θ2 in relation to the tread circumference, of curved lines connecting respective width centers of first main grooves 2 and second main grooves 3 are gradually decreased from respective ends to the tread width center in the range of 90 to 40 deg., and they are gradually decreased from the tread width center to the vicinities of respective edges in the range of 50 to 10 deg.. The edges of blocks B1 , B2 and the edges of sipes S are formed into the length three to ten times on the equatorial plane and five to fifteen times on the meridian section by the magnification corresponding to the block arrangement pitch length of the total length projected to the tire equatorial plane and the tire meridian section. The negative ratio of a tread 1 is in the range of 35 to 45%, and the 300% modulus of the tread rubber is in the range of 40 to 110kgf/cm<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for a motorcycle having a block pattern formed by providing a large number of intersecting main grooves in a tread rubber of a tread portion and forming a plurality of blocks by these intersecting main grooves. Regarding
In particular, the present invention relates to a pneumatic tire for a motorcycle, in which the turning performance, the braking performance and the traction performance of the motorcycle when running on ice and snowy roads are remarkably improved.

[0002]

2. Description of the Related Art In order to adapt a tire to use on a snowy road surface, a tread rubber of a tread portion is provided with a plurality of intersecting main grooves, and a block pattern in which a plurality of blocks are formed on the tread portion by these intersecting main grooves is used. Although equipped with pneumatic tires for motorcycles are widely used,
To date, there is no tire that can sufficiently satisfy the driver's requirements regarding turning performance, braking performance and traction performance.

An example of the above block pattern is shown in FIG. 2 as a development view of a tread. FIG. 2 is a development view in which the circumferential length of the development width TW (arc length) between the end edges TE of the tread surface 1 is matched with the circumferential length of the tire equatorial plane E for convenience. In the tread pattern of FIG. 2, the main groove 5 extends in a zigzag direction along the circumference of the tread 1, and the main grooves 6 and 7 extend in the width direction of the tread 1 and intersect the main groove 5, A block pattern in which blocks B _C , B _S , and B _S −1 are formed by 6 and 7, and these blocks are further divided by sub-grooves 8 and 9.
Each block is provided with sipes Si (slits).

[0004]

The block pattern shown in FIG. 2 is similar to the pattern widely applied to passenger car or truck-bus tires, which takes into account the driving behavior peculiar to motorcycles. Then, the block pattern for motorcycles to be used on ice and snow roads has not yet been fully optimized, in other words, the motorcycle with a block pattern that has excellent performance for ice and snow roads in passenger car or truck-bus tires Even if some adjustments are made to the pattern, the application to vehicle tires is such that the running behavior of a motorcycle is represented by the operation of giving a large camber angle at the time of turning. The behavior means that it is insufficient because it has a significantly large difference.

Therefore, all performances of turning performance, braking performance and traction performance on icy and snowy road surface are remarkably improved under the running behavior peculiar to the motorcycle without deteriorating various performances on non-icy and snowy road surface. SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire for a motorcycle having a block pattern capable of sufficiently satisfying the user's request.

[0006]

To achieve the above object, a pneumatic tire for a motorcycle according to the present invention comprises:
In the tire described at the beginning, the intersecting main groove is a first main groove that extends obliquely while arching from one side edge of the tread to the vicinity of the other side edge, and the other in the direction intersecting the first main groove. The first main groove and the second main groove extending obliquely from the side edge to the vicinity of the one side edge in the same convex direction as the first main groove and curved obliquely, and the width of each of the first main groove and the second main groove. The inclination angle of the curve connecting the centers with respect to the circumference of the tread is gradually reduced within the range of 90 to 40 ° from each edge to the center of the tread width, and is 50 to 10 between the center of the tread width and the vicinity of each edge. The blocks that gradually decrease within a range of ° and are divided between adjacent main grooves of the first main groove and the second main groove form a row along each main groove, and go inward from both end edges. Tread of each block up to the position facing each other at the center of the tread width in each row of blocks The projected length with respect to the circumference is the largest at the block located at the edge, and gradually decreases inward from this block, the block is provided with one or more sipes, and the orientation of the placement of the sipes is at the edge position. From the block to the opposite position block along the direction of the block row,
The ratio of the total length of the edge of the block and the edge of the sipe projected on the tire equatorial plane and the tire meridional section to the block arrangement pitch length is within the range of 3 to 10 times on the equatorial plane, and the meridional section. Above is in the range of 5 to 15 times, the negative ratio of the tread is in the range of 35 to 45%, and the 300% modulus of the tread rubber is 40 to 110 kgf /
It is characterized by being in the range of cm ² .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on an embodiment shown in FIG. FIG. 1 is a development view of a tread surface of an example tire. For convenience of illustration, the developed view shows the circumferential lengths of the end edges TE ₁ and TE ₂ of the tread 1 in accordance with the circumferential length of the tread 1 on the tire equatorial plane E. Reference numeral TW is a developed width (arc length) of the tread 1.

In FIG. 1, reference numerals 2 and 3 are intersecting main grooves, and these intersecting main grooves are an intersecting arrangement of the first main grooves 2 of the multiple arrangement and the second main grooves 3 of the multiple arrangement. The first main groove 2 and the second main groove 3 are respectively provided on one side edge TE _{1 of the} tread _1.
And open to the other side edge TE _2, extends obliquely curved in arcuate first main groove 2 on the other hand from the side edges TE ₁ to the other side edge TE ₂ vicinity, many second main groove 3 is present In the direction intersecting the first main groove 2, the second main body 2 extends from the other side edge TE ₂ to the vicinity of the one side edge TE _{1 in the} same convex direction as the first main groove 2 in an arched shape and extends obliquely.

Inclination angles θ ₁ with respect to the circles C ₁ and C ₂ of the tread 1 of the curves L ₁ and L ₂ (shown by the alternate long and short dash line) connecting the width centers of the first main groove 2 and the second main groove 3, respectively. θ ₂ is the width T of the tread 1 from the opening edge TE ₁ , TE _{2 of} each main groove 2, 3.
90 to 40 at the center of W, that is, at the equatorial plane E of the tire
While gradually decreasing within the range of 50 °, it gradually decreases within the range of 50 to 10 ° from the width center of the tread 1 to the vicinity of the edges TE ₁ and TE ₂ , that is, between the main groove ends 2 _E and 3 _E. Note the inclination angle θ _1, θ ₂ is the angle of circumference C _1, C ₂ and the curve L _1, curve L ₁ at the point of intersection between L _2, L ₂ the tangent makes with the circumference C _1, C _2, the width The curves L ₁ and L ₂ are smoothly connected at the center of the TW. The first main groove 2 communicates with the second main groove 3 and the second main groove 3 communicates with the first main groove 2 at the ends 2 _E , 3 _E.

The blocks defined by the first main grooves 2 adjacent to each other and the second main grooves 3 adjacent to each other are divided into block blocks B ₁ -1 along the first main grooves 2 as shown in the figure. ~ B ₁ -N
(N = 1, 2, ..., I ,.
5) is formed and the block row B is formed along the second main groove 3.
_{2 -1~B 2 -N (N = 1,2} , ···, i, ···,
n, in the illustrated example, n = 5). Block B ₁ -1,
B ₂ -1 is outermost block located at the edge TE _1, TE _2.

[0011] Each row of blocks B ₁ -1~B ₁ -N directed from both side edges TE _1, TE ₂ inwardly here, B ₂
-1 to B ₂ -N, center of tread width (tire equatorial plane E)
Each of to a position opposite at block B ₁ -1~B ₁ -
i, B ₂ -1~B projected length for the ₂ -i circumferential tread 1, the block B ₁ is located in the edge TE _1, TE ₂ -
1, B ₂ −1 is the maximum, and gradually decreases inward from this block. In the illustrated example, the block B ₁ −
3 and the block B _2-3 are opposed to each other with the first main groove 2 and the second main groove 3 interposed therebetween, and therefore the symbol i = 3.

That is, each block B₁-1 to B₁-I and
And each block B_Two-1 to B_TwoThe projection length of -i is
L₁-1-L₁-I and the latter is L_Two-1-L_Two-I and
If you do, L₁-1> L₁-2> ...> L₁-I
L_Two-1> L_Two-2> ...> L_Two-I. Figure
In the example shown, L₁-1> L₁-2> L₁-3, L_Two-1> L
_Two-2> L_Two-3. The circumference that determines the projection length and
Indicates the circumference passing through the innermost end of each block.

As is apparent from FIG. 1, each block
B₁-(I + 1) ~ B₁-N is each block B_Two -I ~ B
_Two -2, while each block B_Two -(I + 1) ~
B_Two-N is each block B₁-I ~ B₁Corresponds to -2.
In the illustrated example, block B ₁-4, B₁-5 is a block
K B_Two -3, B_Two -2, block B_Two -4, B_Two 
-5 is block B₁-3, B₁-2.

All blocks are one or more (2 in the illustrated example).
Book) sipe S, and the direction of the array of this sipe S is
Each block B up to the opposite position₁-1 to B₁−
i, B _Two -1 to B_Two -I, but B in the illustrated example₁-1-
B₁-3, B_Two -1 to B_Two Each block is up to -3
It should be along the line. The sipe S is
It is possible to have a bent portion inside.

[0015] Here in block B ₁ -1~B ₁ -i, B ₂
−1 to B ₂ −i and the edge of the sipe S are connected to the tire equatorial plane E
And tire meridional section (plane orthogonal to tire equatorial plane E)
When projected onto the block arrangement pitch p, the total length of these edges is 3 to 10 times on the tire equatorial plane E, and 5 to 15 times on the tire meridional section. It is necessary to be within the range. The sipe S is an ultrafine groove, and the edge length is calculated.

Further, the ratio of the actual developed areas of the main grooves 2, 3 and the sipe S to the total surface area of the tread 1, that is, the negative ratio, is within the range of 35 to 45%, and the 300% modulus of the tread rubber is. 40-110kg
It must be within the range of f / cm ² .

The tire having the above-mentioned block pattern is conventionally composed of a pair of bead portions and a pair of sidewall portions, and a tread portion continuous with these sidewall portions, and these portions extend between bead cores embedded in the bead portion. The carcass ply is reinforced by a carcass ply of one or more plies of organic fiber, and the carcass ply may have either a radial structure or a bias structure, but is particularly suitable for the bias structure. The radial structure is provided with a belt for reinforcing the tread portion on the outer periphery of the carcass ply, and the bias structure is provided with a breaker or omitted.

The pneumatic tire for a motorcycle having the block pattern having the above-mentioned structure in the tread portion first has both end edges TE of the tread 1 when mounted on the front.
Inclination angle θ ₁ , θ between ₁ and TE ₂ to the center of tread width
The first main groove 2 part and the second main groove 3 part in which ₂ is gradually reduced within the range of 90 to 40 ° have a combined force (vector value) of the braking force (vector value) and the lateral force (vector value). The arrangements are substantially orthogonal to each other, and this works to improve the grip performance (road surface gripping property) on the snowy and snowy road surface under rolling conditions in which the braking force and the lateral force simultaneously act on the tire.

Next, in the rear mounting, the inclination angle θ ₁ between the center of the tread width and the vicinity of both side edges TE ₁ and TE _{2 is}
The traction force (vector value) of the first main groove 2 portion and the second main groove portion where θ ₂ is gradually reduced within the range of 50 to 10 °
And the lateral force (vector value) are almost orthogonal to the combined force (vector value), which is the grip performance on the ice and snow road surface under rolling conditions in which the traction force and the lateral force act on the tire at the same time. Work to improve.

The action direction component of the lateral force input to the ground contact area of the rear tire at the time of turning is the largest at the edges TE ₁ and TE ₂ , and gradually decreases from there toward the center of the width TW of the tread 1. each block B ₁ -1~B ₁ -i, B ₂
-1~B ₂ -i tread 1 of the outermost blocks B ₁ -1 projection length in the circumferential, by sequentially decreasing as the direction from B ₂ -1 inwardly, the acting direction component of the lateral force It is possible to obtain an appropriate block projection length distribution, and as a result, the grip of the rear tire is particularly improved.

[0021] Each block B ₁ -1~B ₁ -i, B ₂
-1~B by ₂ -i of the direction of arrangement of sipes S can be along the direction of the respective block rows, it is possible to equalize the block rigidity against input any orientation which acts on the ground area, or else If this is not the case, it will be possible to avoid this even if uneven block rigidity distribution is unavoidable, such as showing extremely low rigidity for input in a certain direction.
As a result, the grip performance is significantly improved in both the front mounting and the rear mounting described above.

The projection total length on the equatorial plane E is 3 to 10 times in terms of the magnification of the total projection length of the block edge and the edge of the sipe S on the tire equatorial plane E and the tire meridian section with respect to the pitch p. Within the range of, the front mounting and the rear mounting both have an advantageous effect on the lateral force acting on the tire during vehicle turning, and by setting the range within 5 to 15 times on the meridional section, the front mounting, Combined with the rear, it exerts an advantageous effect on the braking force when traveling straight ahead, and in any case, it exerts the effect of greatly improving grip performance in response to various traveling conditions.

If the total projection length is less than 3 times on the equatorial plane E and less than 5 times on the meridional section, the edge effect on the ice and snow surface is not sufficiently obtained, while the equator is not obtained. If the total length of the surface E exceeds 10 times and the total length of the meridional cross section exceeds 15 times, the block rigidity is excessively reduced and the wear resistance and heat resistance of the tread rubber are deteriorated. Is.

Further, by setting the negative ratio within the range of 35 to 45%, the drainage property during running on the wet road surface can be made excellent, and at the same time, the wear resistance of the tread rubber can be kept superior. You can If the negative ratio is less than 35%, sufficient drainage cannot be obtained, while 45
%, It is not possible because the effective ground contact area decreases too much and the wear resistance is impaired.

Further, the edge effect is made effective by setting the 300% modulus of the tread rubber to 40 to 110 kgf / cm ^2, and if it is less than 40 kgf / cm ² , the abrasion resistance of the tread rubber is lowered and 110 kgf / cm ² If it exceeds / cm ² , there will be a problem that the performance on ice and snow roads will deteriorate.

[0026]

EXAMPLE A pneumatic bias tire for a motorcycle having a size of 2.75-14 and a tread pattern according to FIG. The carcass consisted of 840D / 2 nylon cord overlapping plies (plies rolled up around the bead core and overlapped at the tread), and the breaker was omitted. The development width TW of tread 1 is 7
8 mm.

The inclination angles θ ₁ and θ ₂ of the first main groove 2 and the second main groove 3 are 90 ° at the edges TE ₁ and TE ₂ , 50 ° on the tire equatorial plane E, and the ends 2 _E , It was 35 ° at 3 _E. The block arrangement pitch p is 25 mm, and the magnification of the total edge projection length on the tire equatorial plane E is 7 times and the magnification of the total edge projection length on the tire meridional section is 10 times with respect to this arrangement pitch p. The negative ratio was 40%. 300% modulus of tread rubber is 65kgf / cm ²
It is.

In order to evaluate the effect of the embodiment, a conventional tire having a tread pattern shown in FIG. 2 was prepared. The arrangement pitch p of the blocks of this tire is 28.8 mm, the magnification of the total edge projection length on the tire equatorial plane E with respect to this arrangement pitch p is 5.3 times, and the total length of the edge projection on the tire meridional section is Magnification was 9.7 times and all matched to the example except that the negative ratio was 46%.

Each tire of the example and the conventional example was mounted on a motorcycle, and an experienced vehicle driver carried out an actual vehicle feeling test on a snowy road surface. The evaluation items are acceleration performance (traction performance), braking performance and turning performance, and the test results are expressed by an index with the conventional example being 100. In the embodiment, acceleration performance is 110, braking performance is 110, and turning performance is 115. Therefore, the driver can conclude that these values are values that the user is sufficiently satisfied with. In addition, it has been confirmed that no problems will occur even in a field test on non-icy snowy roads.

[0030]

As described above, according to the present invention, while the performance on a road other than an ice / snow road surface is sufficiently maintained, when traveling on an ice / snow road surface under a running characteristic peculiar to a motorcycle which is significantly different from other vehicles, the conventional tire is used. It is possible to provide a pneumatic tire for a motorcycle in which all the traction performance, the braking performance and the turning performance, which could not be obtained at all, are remarkably improved and the user's demand can be sufficiently satisfied.

[Brief description of the drawings]

FIG. 1 is a development view of a tread surface of a tire according to the present invention.

FIG. 2 is a development view of a tread surface of a tire of the conventional invention.

[Explanation of symbols]

1 Tread 2 First main groove 3 Second main groove θ ₁ Angle of first main groove θ ₂ Angle of second main groove B ₁ , B ₂ Block S Sipe TE ₁ , TE ₂ Edge of tread TW Tread of tread Expansion width

Claims (1)

[Claims] 1. A pneumatic tire for a motorcycle, comprising a block pattern formed by providing a large number of intersecting main grooves in a tread rubber of a tread portion and forming a plurality of blocks by these intersecting main grooves, wherein Is a first main groove that curves in an arch shape and extends obliquely from one side edge to the vicinity of the other side edge of the tread, and from the other side edge to the vicinity of the one side edge in a direction intersecting the first main groove. It is composed of a second main groove that is curved in an arch shape and extends diagonally in the same convex direction as the first main groove, and an inclination with respect to the tread circumference of a curve that connects the width centers of the first main groove and the second main groove. The angle gradually decreases within the range of 90 to 40 ° from each edge to the center of the tread width, and gradually decreases within the range of 50 to 10 ° from the center of the tread width to the vicinity of each edge. Between adjacent main grooves of the main groove and the second main groove The divided blocks form rows along each main groove, and the projected length of each block toward the circumference of the tread to the position facing each other at the center of the tread width inward from each side edge inward. That is, the block located at the edge is the largest, and gradually decreases inward from this block, and the block is provided with one or more sipes, and the direction of the arrangement of the sipes is from the edge position block to the opposite position. The blocks extend along the direction of the row of blocks, and the total length of the edges of the blocks and the edges of the sipes projected on the tire equatorial plane and the meridian section of the tire is multiplied by 3 to the equatorial plane at a magnification with respect to the block arrangement pitch length. It is in the range of 10 times, in the range of 5 to 15 times on the meridional section, and the negative ratio of the tread is in the range of 35 to 45%.
And the 300% modulus of the tread rubber is 40-110
A pneumatic tire for a motorcycle, which is in the range of kgf / cm ² .