JPH05201207A - Pneumatic tire for motorcycle - Google Patents

Abstract

PURPOSE:To improve dry grip on a circuit and to secure wet performance on a road public by providing an inclined main lug groove whose angle of the groove center line against the circumferential direction is gradually increased toward a shoulder part and groove width is gradually decreased and an auxiliary lug groove whose angle of the groove center line is gradually increased. CONSTITUTION:Inclined main lug groove 14 are provided on both sides of a tread center CL with an equal interval in the tire circumferential direction (direction shown by an arrow S) which goes from the tread center CL to a shoulder part 16 and is inclined to the tire kicking-out side (opposite direction to the direction shown by an arrow D), and the inclination direction is alternated. The groove width of the inclined main lug groove 14 is gradually decreased as it gets close to the shoulder part 16, and the inclination angle against the tire circumferential direction is gradually increased. Between the inclined main lug grooves 14, an auxiliary lug groove 18 which is inclined in the same direction as the inclined main lug groove 14 is provided, and the groove width is gradually decreased toward the shoulder part 16. Dry grip performance is thereby improved at high-speed cornering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle pneumatic tire, and more particularly to a motorcycle pneumatic tire having a tread pattern.

[0002]

2. Description of the Related Art A motorcycle used for racing on a circuit uses a so-called slick tire which has no groove on a dry road surface, and has a groove on a wet road surface, which has a negative ratio of the tread pattern (to the total area of the tread). A rain tire having a larger groove area ratio) is used.

On the other hand, since a motorcycle used in a production race (race using a mass-produced vehicle) is also used on a public road, a pneumatic tire to be mounted has a pattern on a tread. Pneumatic tires used in such production races are
The dry grip on the circuit is the most important, and the negative ratio is set as small as possible. An example of a pneumatic tire for a motorcycle used in a production race will be described with reference to FIG.

As shown in FIG. 5, a pneumatic tire 100
The inclined main lug grooves 114 are formed on both sides of the tread center CL of the tread 112 in the tire circumferential direction (see arrow S in FIG. 5).
Direction), these inclined main lug grooves 114 sandwich the tread center CL, and one side in the tire width direction (direction of arrow W in FIG. 5) is one half pitch (in the tire circumferential direction) with respect to the other. P) They are arranged in a staggered manner.

One end of each of the inclined main lug grooves 114 in the longitudinal direction is disposed on the tread center CL, and the shoulder portion 116 goes toward the tire kicking side (the direction opposite to the arrow D direction in FIG. 5). Is inclined to approach. These inclined main lug grooves 114 are formed in the shoulder portion 1
The groove width is gradually increased toward 16.
Further, the tread 112 is provided with sub lug grooves 118 between the inclined main lug grooves 114 in the tire circumferential direction. The inclined main lug groove 114 and the sub lug groove 118 are
The tire is inclined toward the tire kicking side (the direction opposite to the arrow D direction in FIG. 5) from the tread center CL side toward the shoulder portion 116 side.

[0006]

By the way, in a so-called pneumatic tire with a pattern, if many grooves are provided, the drainage property is improved, but the rigidity of the tread is lowered and the dry grip is lowered. In other words, in a pneumatic tire with a pattern, dry grip and wet performance are contradictory issues, and in the case of a pneumatic tire with a pattern used in production races, it is important to focus on dry grip when using the race. However, there is a problem in that it is difficult to secure the wet performance in.

The camber angle of the tire when traveling on a public road is about 0 ° to 30 ° in the normal range, and the region of the tread tire contact surface that is mainly used is from the tread center to the shoulder side. It is within the range up to a point 50% of the dimension between the tread center and the shoulder portion.

On the other hand, it is the dry grip during cornering that is particularly important in circuit driving, and the normal range of the camber angle during cornering is 30 °.
It becomes about 50 °. For this reason, when driving on a circuit, the area of the tire ground contact surface that is mainly used is 50
It is known to be in the range from the point of% to the shoulder portion (100%).

However, in the pneumatic tire 100, the groove width is gradually increased in consideration of the discharge of water in the inclined main lug groove 114 when the road surface is wet, so that the tread 112 is located on the tread center CL side. The negative ratio is larger in the region on the shoulder portion 116 side than in the region.
For this reason, during cornering of the circuit, there is a problem that the region on the shoulder portion 116 side, which is inferior in dry gripping to the region on the tread center CL side, comes into contact with the ground.

Different from the pneumatic tire 100 shown in FIG. 5, a pneumatic tire having an inclined main lug groove with a constant groove width is also known. However, since the wettability on general public roads is emphasized. In addition, the overall groove width is set relatively wide, and it cannot be said that dry gripping is good when cornering the circuit.

Further, as a result of the inventor's measurement of the direction of the abrasion pattern (direction in which the frictional force acts) of the pneumatic tire 100 (driving wheel) after running on the circuit, as shown in Table 1 below, the tread 112 It was discovered by the inventor that the direction of the abrasion pattern differs depending on the site. In addition, 0 of tread peripheral in Table 1
% Is the tread center portion, and 100% is the end portion of the tread on the shoulder side.

[0012]

[Table 1] In consideration of the above facts, the present invention optimizes the shape of the tread pattern, improves the dry grip during cornering on the circuit, and at the same time provides a pneumatic tire for a motorcycle capable of ensuring wet performance on a public road. The purpose is to provide.

[0013]

A pneumatic tire for a motorcycle according to the present invention is arranged along a tire circumferential direction and extends from a center portion of a tread toward a shoulder portion and with respect to an end portion on the center portion side. The end on the shoulder side is arranged on the tire kicking side, the angle of the groove center line with respect to the tire circumferential direction is gradually increased from the center side toward the shoulder side, and the groove width is changed from the center side to the shoulder side. Is arranged between the inclined main lug groove that is gradually reduced toward the tire circumferential direction and the inclined lug main groove, and the shoulder side end is arranged on the tire kicking side with respect to the center side end. With the auxiliary lug groove in which the angle of the groove center line with respect to the tire circumferential direction is gradually increased from the center side toward the shoulder side,
The center part is 0% position and the shoulder part is 100
% Position, the average inclination angle of the center line obtained by averaging the groove center line of the inclined lug main groove and the groove center line of the auxiliary lug groove with respect to the tire circumferential direction is from 0% position to 70% position. 0 ° to 40 °, 30% to 95% position 40 ° to 60 °, 45% position to 100% position 60 ° to 90 °, and the inclined lug The main groove and the auxiliary lug groove have a negative tread ratio of 0.
From 10% to 30% position, 10-18%, 30%
The groove width is set so as to be 7 to 13% from the position to the 60% position and 2 to 9% from the 60% position to the 100% position.

[0014]

In a motorcycle running on a public road, the camber angle of the tire is relatively small because the speed of the motorcycle is slower than that in a race, and the tread area mainly used is near the center of the tread. Therefore, according to the pneumatic tire for a motorcycle of the present invention, when traveling on a wet road surface of a general public road, water between the ground contact portion and the road surface is mainly discharged to the outside of the shoulder portion through the inclined main lug groove. Then, a part is discharged to the outside of the shoulder portion through the sub lug groove. In particular, the inclined main lug groove has a large groove width on the center side of the tread, so that the drainage efficiency is good when traveling on a wet road surface of a general public road.

On the other hand, since the motorcycle inclines as the traveling speed increases during cornering, the pneumatic tire for a motorcycle has a large camber angle when traveling on a dry road surface of a circuit and is mainly used during cornering. The ground contact portion is a region on the shoulder portion side of the tread. At this time, the traction due to the driving force acts on the ground contact portion in the direction along the tangential line in the tire circumferential direction, but at the time of cornering, the cornering force composed of the sum of the traction and the side force acts. Since the side force increases as the cornering speed increases, when the cornering speed increases, the cornering angle (the angle between the direction in which the cornering force acts and the direction in which the traction acts) increases accordingly. According to the pneumatic tire for a motorcycle of the present invention, the average inclination with respect to the tire circumferential direction of the center line obtained by averaging the groove center line of the inclined lug main groove and the groove center line of the auxiliary lug groove as approaching the shoulder portion side Since the angle becomes tight and the average groove width of the inclined lug main groove and the auxiliary lug groove becomes narrow, the cornering force, that is, the frictional force between the tread and the road surface, is increased even when the vehicle runs at high speed. Further, since the tread is input along the longitudinal direction of the auxiliary lug groove, deformation of the tread during cornering is small, and grip during dry road cornering is particularly improved as compared with a conventional pneumatic tire for a motorcycle. Further, during cornering on the wet road surface of the circuit, the water between the ground contact portion and the road surface is drained to the outside of the shoulder portion via the inclined lug main groove and the sub lug groove.

The average inclination angle of the groove center line of the inclined main lug groove and the groove center line of the auxiliary lug groove with respect to the tread center is 0 ° to 40 ° between the 0% position and the 70% position,
40 ° to 60 ° between the 30% position and the 95% position,
Also, between the 45% position and the 100% position, 60 °-
If the angle is out of the range of 90 °, the rigidity of each tread is insufficient and the grip force is reduced, which is not preferable. Further, the negative ratio of the tread is not preferable in the range from the tread center (0% position) to the 30% position, and when it is less than 10%, the drainage property on the wet road surface of general public roads is deteriorated, and when it exceeds 18%. It is not preferable because the rigidity of the tread decreases, and if it is less than 7% in the range from the 30% position to the 60% position, it is not preferable because the drainage performance on the wet road surface of general public roads deteriorates.
If it exceeds, it is not preferable because the rigidity of the tread decreases, and if it is less than 2% within the range from the 60% position to the 100% position, drainage on the circuit wet road surface cannot be expected, and if it exceeds 9%. Rigidity of the tread on the circuit dry road surface is reduced, and improvement in dry grip cannot be expected compared to conventional pneumatic tires for motorcycles.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a partial plan development view of a tread 12 of a pneumatic tire 10 according to an embodiment of the present invention.

As shown in FIG. 1, in the tread 12 of the pneumatic tire 10, inclined main lug grooves 14 are formed on both sides of the tread center CL at equal intervals in the tire circumferential direction (direction of arrow S in FIG. 1). Cage, these inclined main lug grooves 1
4 is a tire width direction with the tread center CL interposed (see FIG. 1).
1) in the tire circumferential direction relative to the other
They are arranged so as to be offset by 2 pitches (P).

One end of each inclined main lug groove 14 in the longitudinal direction is disposed on the tread center CL, and the shoulder portion 16 extends toward the tire kicking side (the direction opposite to the arrow D direction in FIG. 1). Is inclined so as to approach to, and each inclined main lug groove 14 is
One of the tire width directions (the direction of the arrow W in FIG. 1) sandwiching L, the inclination direction is opposite to the other. The other longitudinal end of each inclined main lug groove 14 is the shoulder portion 1.
It is terminated in the vicinity of 6.

These inclined main lug grooves 14 are composed of a center side groove portion 14A on the side of the tread center CL and a shoulder side groove portion 14B on the side of the shoulder portion 16 which is continuous with the center side groove portion 14A.

The center side groove portion 14A has one end on the tread center CL and the other end from the tread center CL to the shoulder portion 16 side, and in the tread peripheral between the tread center CL and the shoulder portion 16 (see FIG. 2). It is located at a 50% position 50% away from the dimension L (hereinafter, the position of the tread center CL is 0% of the reference and the position of the shoulder portion 16 is 100%). Also,
The center side groove portion 14A has a linear shape in the longitudinal direction,
The inclination angle θ1 of the groove center line with respect to the tire circumferential direction (arrow S direction in FIG. 1) is 30 ° in this embodiment. Also,
The center-side groove portion 14A has a groove width W14 as it goes from the tread center CL toward the shoulder portion 16.
A is gradually reduced at a substantially constant rate. On the other hand, the shoulder side groove portion 14B has a linear shape in the longitudinal direction, and one end has a length of 5
The 0% position and the other end are located at the 90% position. Tire circumferential direction of shoulder side groove portion 14B (direction of arrow S in FIG. 1)
The inclination angle θ2 of the groove center line with respect to
It is said to be °. The groove width W14B of the shoulder side groove portion 14B is substantially constant in the longitudinal direction,
The groove width W14A of the center side groove portion 14A is narrower than the narrowest portion.

Further, the tread 12 is provided with sub lug grooves 18 between the inclined main lug grooves 14 in the tire circumferential direction. These inclined main lug grooves 14 are inclined so as to be on the tire kicking side (the direction opposite to the arrow D direction in FIG. 1) from the tread center CL side toward the shoulder portion 16 side. The sub-lug groove 18 has a linear longitudinal direction, and the inclination angle θ3 of the groove center line with respect to the tire circumferential direction (direction of arrow S in FIG. 1) is 55 ° in this embodiment. Further, the sub lug groove 18 has a tread center C
The groove width W18 is gradually reduced at a substantially constant ratio from the L side toward the shoulder portion 16 side.

Further, the average inclination angle θ {(inclined main lugs located within a predetermined range along the tire width direction between the groove center line of the inclined main lug groove 14 and the groove center line of the sub lug groove 18 with respect to the tread center CL. Inclination angle of groove 14 × inclined main lug groove 1
4 length + inclination angle of the sub lug groove 18 x length of the sub lug groove 18) / (length of the inclined main lug groove 14 + length of the sub lug groove 18)} is from the 0% position to the 70% position Between 0 ° to 4
0 °, 40 ° to 6 between 30% position and 95% position
0 °, 60 ° from 45% position to 100% position
90 ° is preferred. The average inclination angle θ is 0 ° to 40 ° from the 0% position to the 70% position, and the average tilt angle θ is 95% from the 30% position.
When the average inclination angle θ is 40 ° to 60 ° between the positions and when the average inclination angle θ is outside the range of 60 ° to 90 ° between the 45% position and the 100% position, the rigidity of the tread 12 is increased. Is insufficient and the grip force is reduced, which is not preferable. In this example, the average tilt angle θ is 0%.
Approximately 30 ° from position to 70% position, Approximately 58 ° from 30% position to 95% position, 10% from 45% position
The distance up to the 0% position is about 63 °.

On the other hand, the negative ratio of the tread 12 is 10% to 18% from the tread center CL (0% position) to 30% position, and 7% from the 30% position to 60% position.
~ 13% 2% ~ 9% from 60% position to 100% position
Is preferred. 3 from the tread center CL (0% position)
The reason why the negative ratio up to the 0% position is set to 10% to 18% is that if it is less than 10%, the drainage property on the wet road surface of general public roads deteriorates, and if it exceeds 18%, the rigidity of the tread 12 is increased. This is because the wear resistance deteriorates. The reason for setting the negative ratio from the 30% position to the 60% position from 7% to 13% is that if it is less than 7%, the drainage performance on the wet road surface of general public roads deteriorates, and exceeds 13%. And the rigidity of the tread 12 is reduced, and the wear resistance is deteriorated. The negative ratio in the tread 12 of the pneumatic tire 10 of this example is 13% from the tread center CL (0% position) to 30% position, and 1 from 30% position to 60% position.
2.4%, 6.1% from 60% to 100%
Is.

The pneumatic tire 10 has a general radial tire structure, and illustration and description of the radial tire structure are omitted.

Next, the operation of this embodiment will be described. During straight running, the pneumatic tire 10 contacts the road surface at the tire width direction central portion of the tread 12, and the ground contact portion 20 at that time is an ellipse elongated in the tire circumferential direction (arrow S direction in FIG. 3) as shown in FIG. It has a shape, and the grounding center line of the grounding portion 20 substantially coincides with the tread center CL. Further, since the two-wheeled vehicle takes a camber angle during cornering, the ground contact portion 20 moves from the tread center CL side to the shoulder portion 16 side, but the camber angle on a general public road is relatively small, and the tread 12 used mainly. Area is 0% position to 50
Within the range to the% position. Therefore, when traveling straight on a wet road surface or traveling on a wet road surface on a public road, the water between the ground contact portion 20 and the road surface (not shown) is mainly the center side groove portion 14A of the inclined main lug groove 14. From the shoulder side groove portion 14B to the shoulder portion 16
It is discharged to the outside, and a part is discharged to the outside of the shoulder portion 16 via the auxiliary lug groove 18.

On the other hand, at the time of cornering, the two-wheeled vehicle has a large camber angle, and therefore the ground contact portion 20 of the tread 12 is used.
Shifts from the tread center CL side to the shoulder portion 16 side.

The normal range of the camber angle when the two-wheeled vehicle runs on a public road is about 0 ° to 30 °, and the grounding portion 20 mainly used is 50% from the tread center CL (0% position). It is the area up to the position. Therefore, when turning on a wet road surface of a public road, the ground contact portion 20
Between the road surface and the road surface is discharged from the center side groove portion 14A to the outside of the shoulder portion 16 via the shoulder side groove portion 14B. In particular, since the center side groove portion 14A has a large groove width, the drainage property is good, and the drainage is efficiently performed during traveling on a general public road.

On the other hand, when the two-wheeled vehicle travels on the circuit, it runs at a high speed, the normal range of the camber angle during cornering is about 30 ° to 50 °, and the grounding portion 20 mainly used is the tread 12's. 100% from 50% position
It is within the range to the position.

The traction T due to the driving force acts on the ground contact portion 20 in the direction along the tangential line in the tire circumferential direction when the vehicle is running, but at the time of cornering, the sum of the traction T and the side force SF as shown in FIG. The cornering force CF consisting of acts. Since the side force SF increases as the cornering speed increases,
As the cornering speed increases, the cornering angle β (angle between the direction in which the cornering force CF acts and the direction in which the traction T acts) increases accordingly. Therefore, within the ground contact portion 20 (mainly within the range from the 50% position to the 100% position) that is mainly used for traveling on the circuit, the cornering angle β is larger than the inclination angle θ1 of the center side groove portion 14A. The inclination angle θ2 of the side groove portion 14B approaches. That is,
Since the frictional force with the road surface is input to the tread 12 along the longitudinal direction of the shoulder groove portion 14B, the tread 12 is less likely to be deformed during cornering during high speed running, and has good wear resistance. Further, since the negative ratio of the tread 12 is made smaller as it gets closer to the shoulder portion 16 side, that is, the gripping property becomes larger as it gets closer to the shoulder portion 16 side, which is particularly required when cornering on a circuit. The grip property can be obtained. Further, as described above, the grounding portion 20 of the tread 12 is less deformed when the cornering force CF acts, and the shoulder portion 16 side has good wear resistance,
Improves grip performance during cornering on the circuit, especially grip sustainability.

During turning on the wet road surface of the circuit, water between the ground contact portion 20 and the road surface is drained to the outside of the shoulder portion 16 through the shoulder side groove portion 14B and the sub lug groove 18.

Further, the inclined main lug groove 14 and the sub lug groove 18
Means that one side in the tire width direction is offset by ½ pitch (P) in the tire circumferential direction with respect to the other with the tread center CL sandwiched on both sides of the tread center. Even if it is made uniform. Therefore, the wear of the tread 12 in the tire circumferential direction is made uniform.

In this embodiment, the inclined main lug groove 14 is composed of the center side groove portion 14A extending linearly and the shoulder side groove portion 14B extending linearly. However, the present invention is not limited to this, and the inclined main lug is not limited thereto. As shown in FIG. 4, the groove 14 may have a shape in which the groove width is gradually reduced and the length is curved.
Similarly, the auxiliary lug groove 18 does not have a linearly extending shape, but as shown in FIG. 4, even if the groove width gradually decreases toward the shoulder portion 16 side and the longitudinal length thereof is curved. Good.

Further, in this embodiment, one sub lug groove 18 is arranged between the inclined main lug groove 14 and the inclined main lug groove 14, but the present invention is not limited to this, and the negative ratio is not limited thereto. If is within a predetermined range, a plurality of sub lug grooves 18 may be arranged between the inclined main lug groove 14 and the inclined main lug groove 14.

In Table 2 below, the pneumatic tire 10 of this embodiment and a conventional pneumatic tire 100 (pneumatic tire shown in FIG. 5) are mounted on an actual vehicle, respectively, and a circuit dry road surface is obtained. Feeling the actual vehicle steering stability (grip performance) during cornering on the circuit dry road surface and the actual vehicle steering stability during running on a public road wet road surface when running on a public road wet road surface (just wet road surface at zero water depth) (Evaluation of perfect score of 10 points).

The tire size is 15 for both the pneumatic tire 10 of this embodiment and the conventional pneumatic tire 100.
The tire pressure was set to 0 / 60R17, and the tire internal pressure was set to the normal condition based on the JIS standard.

[0038]

[Table 2] From the test results shown in Table 2 above, the pneumatic tire 10 according to the present invention has a dry grip during cornering on a circuit dry road surface and a wet road surface on a general public road as compared with a conventional pneumatic tire (see FIG. 5). Steering stability,
It became clear that so-called wet performance was improved.

[0039]

As described above, the pneumatic tire for a motorcycle of the present invention has the tread pattern shape optimized as described above, so that the cornering on a circuit dry road surface is improved as compared with the conventional pneumatic tire. It has an excellent effect that the dry grip at the time and the wettability on the road surface on general public roads are improved.

[Brief description of drawings]

FIG. 1 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention.

FIG. 3 is a plan view of a tread showing a ground contact surface of a pneumatic tire according to an embodiment of the present invention.

FIG. 4 is a plan view of a tread of a pneumatic tire according to another embodiment of the present invention.

FIG. 5 is a plan view of a tread of a conventional pneumatic tire.

[Explanation of symbols]

 10 Pneumatic Tire 12 Tread 14 Inclined Main Lug Groove 14B Shoulder Side Groove Part 14A Center Side Groove Part 16 Shoulder Part 18 Sub Lug Groove CL Tread Center

Claims (1)

[Claims] 1. A groove which is arranged along the tire circumferential direction, extends from the center portion of the tread toward the shoulder portion, and has the shoulder portion side end portion arranged on the tire kicking side with respect to the center portion side end portion. An inclined main lug groove in which the angle of the center line with respect to the tire circumferential direction is substantially gradually increased from the center portion side toward the shoulder portion side, and the groove width is substantially gradually reduced from the center portion side toward the shoulder portion side. The inclined lug main groove is arranged between the tire circumferential direction, the shoulder side end portion is arranged on the tire kicking side with respect to the center side end portion, and the angle of the groove center line with respect to the tire circumferential direction is the center portion. And a sub-lug groove that is gradually increased from the side toward the shoulder portion. When the center portion is at the 0% position and the shoulder portion is at the 100% position, the inclination is increased. The average inclination angle with respect to the tire circumferential direction of the center line average groove center line of the grayed main groove and the a groove center line of the sub-lug grooves, 0 between 0% position to 70% position
40 ° between 40% and 30% to 95%
6 ° between 60 ° and 45% position to 100% position
The inclination ratio of the inclined lug main groove and the auxiliary lug groove is set to 0 ° to 90 °, and the negative ratio of the tread is 10% to 18% from 0% position to 30% position, and 60% from 30% position. 7 up to% position
~ 13%, 2 from 60% position to 100% position
A pneumatic tire for a motorcycle, the groove width of which is set to be 9%.