JP2011189809A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire for a motorcycle for achieving both grip performance enabling sporty traveling without anxiety on a circuit or the like, and wet performance for traveling without anxiety on general roads. <P>SOLUTION: The tire for the motorcycle includes: a pair of bead parts; a pair of side walls continuing into the bead parts; and a tread which stretches over both of the side walls in a toroidal shape, wherein a rotational direction when mounted on the motorcycle is assigned. The tire for the motorcycle is provided with a bent main groove 8 including: a first groove extending in a tread circumferential direction within a ground contact area at linear traveling on a tread road surface; and a second groove 7 extending from the end part at the assigned tire rotation direction side of the first groove 6 at a slant towards the outside in a tread width direction in the assigned tire rotation direction, and further provided with an auxiliary groove 9 at a position spaced from the outside in the tread width direction of the second groove 7 as well as the end part at the assigned tire rotation direction side of the second groove 7 in the assigned tire rotation direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire for motorcycles, and more particularly, to a pneumatic tire for motorcycles that achieves both grip performance that enables sporty traveling with peace of mind on circuits, etc., and wet performance that can safely travel on ordinary roads. .

  Conventionally, in traveling on a general road, a motorcycle pneumatic tire having a pattern in which a large number of inclined grooves are arranged in a tread portion is known in order to ensure steering stability on a dry road surface and a wet road surface (for example, (See Patent Document 1).

Here, especially recently, there is an increasing need to use pneumatic tires for motorcycles for general roads for circuit driving. When conventional tires as described above are used for this purpose, circuit driving is required. For example, the grip required for sporty driving was not sufficient, and it was necessary to improve the grip performance.
In particular, a tire is desired in which the braking force when traveling straight and the lateral force when turning are improved by increasing the gripping force of the front wheel tire that serves as the steering wheel.

On the other hand, a pneumatic tire for motorcycles having a pattern as shown in FIG. 1 has been proposed as a pneumatic tire for motorcycles dedicated to circuit running (see, for example, Patent Document 2).
When the area that becomes the tire contact surface when a tire filled with the specified internal pressure in the specified rim is run straight under the specified load is called the straight contact area, the pattern shown in FIG. In the region Q1, a first inclined groove 91 inclined across the equator plane CL, and a second inclined groove 92 provided so as not to cross the equator plane CL corresponding to each of the first inclined grooves 91, Are arranged in the circumferential direction at intervals.
The first inclined groove 91 and the second inclined groove 92 corresponding to the first inclined groove 91 are separated from each other, and are provided so as to be inclined in opposite directions with respect to the equator plane CL.
In this pattern, in order to improve the grip performance required for circuit driving, the ratio (negative rate) of the groove area to the total area of the tread part is extremely low.

JP 2007-331596 A Design Registration No. 1312918

However, since the tire described in Patent Document 2 has a low negative rate and has poor drainage, the wet performance is not sufficient, and there is a problem that the road cannot be safely driven.
Further, when the negative rate is reduced in this way, the out-of-plane bending rigidity is increased, the ground contact area is reduced during turning, and the improvement of the grip performance is hindered.

  The present invention has been made in view of such problems, and it is possible to achieve both a grip performance that enables sporty travel with peace of mind on a circuit and a wet performance that can travel with peace of mind even on ordinary roads. An object is to provide a pneumatic tire for a motorcycle.

The inventors have made extensive studies to solve the above problems.
As a result, it is possible to achieve both grip performance and wet performance by providing the main groove on the tread and the auxiliary groove spaced apart in the tire rotation direction at the end of the main groove in the tire rotation direction as appropriate arrangement and shape. The new knowledge of being able to be made was acquired.

The gist configuration of the pneumatic tire according to the present invention is as follows.
(1) A motorcycle air comprising a pair of bead portions, a pair of sidewall portions connected to the bead portion, and a tread straddling a toroidal shape between both sidewall portions, and a rotation direction when the vehicle is mounted is specified. In entering tires,
A first groove extending in a tread circumferential direction within a straight traveling contact area of the tread surface, and the designated tire obliquely outward in the tread width direction from an end of the first groove on the designated tire rotation direction side. Comprising a bent main groove consisting of a second groove extending in the rotational direction;
Further, the automatic groove further includes an auxiliary groove at a position spaced apart in the designated tire rotation direction from an end portion of the second groove in the tread width direction and an end portion of the second groove in the previous period on the designated tire rotation direction side. Pneumatic tire for motorcycles.

(2) In the connecting portion between the first groove and the second groove, when the width of the second groove is A, and the width of the auxiliary groove is B,
A ≦ B ≦ 3A
The pneumatic tire for a motorcycle according to the above (1), characterized in that:

  (3) The pneumatic tire for a motorcycle according to the above (1) or (2), characterized in that the entire first groove is disposed in a straight contact area.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire for motorcycles which made the grip performance and the wet performance compatible in a high dimension can be provided by optimizing the shape and arrangement | positioning of the groove | channel in a tread.

It is an expanded view which shows the tread of the conventional tire. It is sectional drawing which shows the tire for two-wheeled motor vehicles of this invention. (a) is a development view showing a tread of a tire for a motorcycle according to the present invention. (b) It is a figure which shows the contact length l and the contact width w.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 2 is a cross-sectional view showing a motorcycle tire (hereinafter referred to as “tire”) according to an embodiment of the present invention.
As shown in FIG. 2, the tire according to the present embodiment is a pair of bead portions 1, a pair of sidewall portions 2 connected to the bead portion 1, and a tread 3 straddling the side wall portions 2 in a toroidal manner, according to the conventional practice. Is provided.
The bead portion 1 has a bead core 1a, a carcass 4 extends between the bead cores 1a in a toroidal shape, and a belt 5 is provided outside the carcass 4 in the tire radial direction.

FIG. 3 (a) is a diagram showing a developed area Q of the tire tread 3 according to one embodiment of the present invention.
First, as shown in FIG. 3 (a), the contact area Q of the tread 3 is divided into a straight contact time contact area Q1 of the vehicle and an outer contact area Q2 outside the tread width direction from Q1. The “straight contact area” refers to an area that becomes a tire contact surface when a tire in which a specified rim is filled with a specified internal pressure travels straight under a specified load.

The tire according to the present embodiment has a tread 3, a first groove 6 extending in the tread circumferential direction within the straight contact area Q1, and a designated tire rotation direction of the first groove 6 (designated as a tire rotation direction when the vehicle is mounted). A second groove extending in the circumscribed area Q2 in the designated tire rotation direction obliquely from the end toward the outer side in the tread width direction. .
The first groove 6 and the second groove 7 are connected to form a main groove 8.
Further, the auxiliary groove 9 is provided at a position outside the second groove 7 in the tread width direction and spaced from the end of the second groove 7 in the designated tire rotation direction.
As shown in FIG. 3 (a), the main groove 8 forms a pattern alternately arranged on the tread surface on one side and the other side sandwiching the tire equator plane CL with an interval in the tire circumferential direction. The same applies to the auxiliary groove 9.
Here, “the first groove extends in the straight contact area” means that 70% or more of the groove area of the first groove 6 is in the straight contact area Q1, and the first groove 6 may be partially placed across the circumscribed area Q2. In addition, “the second groove extends in the circumscribed area” means that 50% or more of the groove area of the second groove 7 is in the circumscribed area Q2, and partly in the straight-adjacent area It may be placed across Q1.

In order to improve the grip performance and wet performance, which are the objects of the present invention, the tension rigidity of the tread with respect to the input (external force) from the road surface is maintained, the deformation of the land portion due to the external force is suppressed as much as possible, and the contact area is secured. However, on the other hand, it is necessary to improve drainage in the ground contact surface Q by the groove.
For that purpose, it is necessary to arrange the grooves in the tread along the direction of the external force. That is, with such an arrangement, the land portion is most difficult to deform, and the tensile rigidity against the external force is maintained, and the slip of the land portion that occurs in the direction of the external force is caused by water in the groove. This is because drainage is improved due to relative movement.

In the tire of the present invention, the first groove 6 is arranged in the tread circumferential direction, that is, in the direction along the braking force during straight traveling, in the straight traveling contact area Q1.
As a result, when the vehicle goes straight, deformation of the land portion due to external force is suppressed, and a ground contact area in the straight traveling contact area Q1 is secured, so that grip force is improved. In addition, the drainage performance in the straight contact area Q1 as described above is also improved.

The second groove 7 extends in the designated tire rotation direction obliquely from the end portion in the designated tire rotation direction of the first groove 6 toward the outer side in the tread width direction. That is, the second groove 7 is provided in the direction along the input during turning within the ground contact surface during turning of the vehicle.
Thereby, when the vehicle turns, the deformation of the land due to the external force is suppressed, and the ground contact area in the outer area Q2 is secured, so that the grip force is improved. In addition, the drainage performance in the outer circumscribed area Q2 is improved as described above.

Here, as shown in FIG. 3 (a), it is preferable that the second groove 7 has a shape in which the angle with respect to the tread circumferential direction gradually increases as going to the outer side of the tread.
In a motorcycle, as the running state changes, the position of the ground contact surface changes and the required performance also differs. That is, as the camber angle increases, the ground contact surface becomes the outer side in the tread width direction, and the grip performance in the lateral direction becomes more important. Therefore, the outer side in the tread width direction of the groove 7 needs to have a shape along the tread width direction. Because.

  Furthermore, the tire of the present invention has the second groove 7 connected to the end of the designated groove rotation direction of the first groove 6 and is continuous as a drainage path, so that the drainage of the tread is improved, and as a result The wet performance of the tire is improved.

In particular, as shown in FIG. 3 (b), when the grounding length of the tread grounding surface when a tire with a prescribed rim filled with a prescribed internal pressure is traveled straight under a prescribed load and the contact width is w, As shown in FIG. 3 (a), the tread circumferential length L and the tread width direction length W of the main groove 8 are:
L ≧ l and W ≧ 2w
It is preferable to satisfy.
When L <l or W <2w, the drainage effect by the main groove 8 is not sufficient, and the effect of connecting the groove 6 and the groove 7 is not sufficient.

Here, in the tire of the present invention, the auxiliary groove 9 is further provided at a position outside the second groove 7 in the tread width direction and spaced from the end of the second groove 7 in the designated tire rotation direction. It is important to have.
When turning, it is effective that the block can be deformed so as to ensure a ground contact area according to the camber angle, that is, it is effective to reduce the out-of-plane bending rigidity. The main groove 8 and the auxiliary groove 9 are connected to each other by being located at the outer side in the tread width direction of the second groove 7 and at a position away from the end portion in the designated tire rotation direction of the second groove 7 in the designated tire rotation direction. Compared to the case, the distance that the groove extends in the direction of the input during turning is reduced, so the rigidity against the input (out-of-plane bending rigidity) is reduced, the ground contact area is increased, and the grip performance during turning is improved. Can do. Thereby, the lateral force at the time of turning can be largely generated.

Note that the distance D of the auxiliary groove 9 from the end of the second groove 7 in the designated tire rotation direction is preferably 20 mm or less.
This is because if it is larger than 20 mm, the auxiliary groove 9 and the main groove 8 are too far apart and the out-of-plane bending rigidity cannot be sufficiently reduced.

Here, it is preferable that the width A of the second groove 7 and the width B of the auxiliary groove 9 at the connection portion between the first groove 6 and the second groove 7 satisfy the following relationship.
A ≦ B ≦ 3A
If the width B of the auxiliary groove 9 is smaller than the width A, the effect of reducing the out-of-plane bending rigidity is insufficient. On the other hand, if the width B is larger than the width A, the groove portion that hinders input during turning becomes large. This is because the grip strength is too low.
Here, “the width of the second groove at the connecting portion” refers to connecting the two bending points 8a when the first groove and the second groove are connected in a bent shape. The length of the line segment.

When the relationship between the width B and the width A is within the above range, specifically, for example, in a tire having a tire size MCR120 / 70ZR17 / C, the width A is preferably 2 mm or more and 7 mm or less. This is because if it is less than 2 mm, the drainage performance of the main groove is lowered, and if it is larger than 7 mm, the pattern rigidity becomes too small and the steering stability is lowered.
Correspondingly, the width B is preferably 2 mm or more and 14 mm or less. If it is less than 2 mm, the out-of-plane bending rigidity will not be sufficiently reduced, and an improvement in lateral force cannot be expected. If it is greater than 14 mm, the input will be hindered and the grip force will be reduced.

For example, in a tire having a tire size MCR120 / 70ZR17 / C, the length C of the auxiliary groove 9 shown in FIG. 3 (a) is preferably 3 mm or more and 30 mm or less. This is because if it is less than 30 mm, the effect of reducing the out-of-plane bending rigidity is not sufficient, and if it is more than 30 mm, the gripping force is reduced.
Furthermore, the distance E between the auxiliary groove 9 and the main groove 8 in the tread width direction is preferably 1 mm or more. This is because if it is less than 1 mm, the gripping power decreases.

Furthermore, in the tire according to the present invention, it is preferable that the entire first groove 6 is positioned in the straight contact area Q1 of the vehicle.
This is because, when the entire first groove is in the ground contact area during straight travel, the tensile rigidity with respect to the input during straight travel is increased, the ground contact area is increased, and the grip performance during straight travel is most improved.

  The tire of the present invention is suitable for a front wheel tire that is a steered wheel because it increases the braking force when traveling straight and generates a large lateral force when turning. This is an effective technique for tires for the rear wheels when the frequency of applying is high.

Next, in order to confirm that the tire of the present invention has a difference in grip performance and drainage from the conventional example, a test run on a dry road surface and a wet road surface by a driver was performed.
Here, as Invention Examples 1 to 12, front tires having a tread of the type shown in FIG. 3 (a) and a tire size of MCR120 / 70ZR17 / C were manufactured as prototypes.
As a conventional example, a front wheel tire having a tread of the type shown in FIG. 1 and a tire size of MCR120 / 70ZR17 / C was prepared.
As the rear tire, a general-purpose tire having a tire size MCR190 / 50ZR17 / C was commonly used.

Here, in the tires according to Invention Examples 1 to 6, the ratio B / A between the width B of the auxiliary groove and the width A of the second groove in the connecting portion between the first groove and the second groove is different from each other. Other features are common.
Further, in the tires according to Invention Examples 1 to 6, the entire first groove is in the straight traveling contact area Q1, while the tires according to Invention Examples 7 to 12 are 80% of the groove area of the first groove. Is in Q1 when traveling straight.
The specifications of each tire are shown in Table 1.

These tires were mounted on a rim with a rim size of MT3.50 × 17, and the internal pressure was set to 250 kPa. The tires were attached to the front and rear wheels of a 1000 cc motorcycle, and a test was conducted to evaluate grip performance and wet performance.
The grip performance was evaluated by indexing the level that satisfies the absolute level as 100, based on the sensory evaluation of the feeling when the driver tested the dry road surface.
Similarly, the wet performance was evaluated by indexing the level that can be satisfied as an absolute level as 100, by scoring the feeling when the driver made a test drive on a wet road surface by sensory evaluation.
These indices indicate that the larger the value, the better the performance.
The test results are shown in Table 2 below.

  As shown in Table 2, it can be seen that the tires of Invention Examples 1 to 12 according to the present invention are both superior in grip performance and wet performance than the conventional tire.

In addition, according to the comparison of Invention Examples 1 to 6 and Comparison of Invention Examples 7 to 12, Invention Examples 2 to 4 and 8 to 10 in which the ratio B / A is in the preferred range are inventions in which the ratio B / A is outside the preferred range It can be seen that the grip performance is particularly excellent as compared with Examples 1, 5, 6, 7, 11, and 12.
Further, Invention Examples 1 to 6, 2 and 8, 3 and 9, 4 and 10, 5 and 11, and 6 and 12, the first groove is entirely in the straight traveling contact area Q1. It can be seen that the grip performance is superior to those of Invention Examples 7 to 12 in which 80% of the groove area of the first groove is in the straight contact area Q1.

  We can manufacture pneumatic tires for two-wheeled vehicles that provide both the grip performance that enables sporty driving with peace of mind on circuits, etc., and the wet performance that allows safe driving on ordinary roads, and provide them to the market.

1 Bead section
1a Bead core
2 Side wall
3 tread
4 Carcass
5 belt
6 First groove
7 Second groove
8 Main groove
8a Inflection point
9 Auxiliary groove
91 Inclined groove
92 Inclined groove
A Width of second groove at connecting part
B Auxiliary groove width
C Auxiliary groove length
D Distance between main groove and auxiliary groove in the tire rotation direction
E Distance between main groove and auxiliary groove in the tire width direction
L Main groove tread circumferential length
W Main groove tread width length
l Ground contact length
w Grounding width
Q area
Q1 Areas where you go straight
Q2 Outside area
R Tire rotation direction
CL tire equator

Claims (3)

In a pneumatic tire for a motorcycle comprising a pair of bead portions, a pair of sidewall portions connected to the bead portion, and a tread straddling between the sidewall portions in a toroidal shape, the rotation direction when the vehicle is mounted is specified. ,
A first groove extending in a tread circumferential direction within a straight traveling contact area of the tread surface, and the designated tire obliquely outward in the tread width direction from an end of the first groove on the designated tire rotation direction side. Comprising a bent main groove consisting of a second groove extending in the rotational direction;
Further, the automatic groove further includes an auxiliary groove at a position spaced apart in the designated tire rotation direction from an end portion of the second groove in the tread width direction and an end portion of the second groove in the previous period on the designated tire rotation direction side. Pneumatic tire for motorcycles. In the connection portion between the first groove and the second groove, when the width of the second groove is A and the width of the auxiliary groove is B,
A ≦ B ≦ 3A
2. The pneumatic tire for a motorcycle according to claim 1, wherein:   3. The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the entire first groove is disposed in a straight contact area.

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