JPS61108005A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To obtain satisfactory water expelling performance during straight running and turning in a rainy weather, by forming crest portions at connecting parts between central inclined grooves and outside inclined grooves to form an inverted W-shape with respect to a circumferential direction of a tire. CONSTITUTION:A trough portion 11 is formed at a connecting part between a pair of central inclined grooves 8a, and the center of the trough portion 11 coincides with an equator line E of a tire. A pair of crest portions 12 are formed at connecting parts between the central inclined grooves 8a and outside inclined grooves 8b. Thus, these grooves 8a and 8b are formed in a substantially inverted W-shape with respect to a circumferential direction of the tire. The outside inclined grooves 8b extend straight in a central tread portion 2a from the tops of the crest portions 12 to both road contact edges 6, and are bent at the edges 6, from which they extend in side tread portions 2b to both edges 2d and 2e of the tire. Accordingly, rain water is divided to flow along the grooves 8a and 8b.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a tread pattern for use in high-speed motorcycles.

(Prior Art) In recent years, high-speed driving of vehicles has increased, and the required performance of tires mounted on these vehicles has become even more severe. In particular, for motorcycle tires, it is necessary to have good straight-line performance and turning performance in terms of handling stability, but what is even more important is that the tires have excellent drainage performance when driving at high speeds in the rain. . Recently, in order to improve the drainage performance of tires, tires with a directional pattern have been used in which the direction of rotation of the tire is determined and the grooves in the tread pattern of the tire are in only one direction.

An example of a conventional pneumatic tire having a directional pattern is the one shown in FIG. FIG. 3 is a radial cross-sectional view of a pneumatic tire filled with air to a specified amount of air pressure. In FIG. 3, 31 is a conventional pneumatic tire for a motorcycle, and the pneumatic tire 31 has a tread portion 32 and a pair of side tread portions 33, 33'
, a pair of bead parts 34, 34', and a carcass part 35 consisting of at least one layer of carcass part. The tread portion 32 is composed of a tread center portion 32a at the center and tread side end portions 32b at both side ends of the tread portion 32. FIG. 4 is a partially exploded view of the tread portion 32 of FIG. 3, and is a diagram showing a conventional tread surface pattern. In FIG. 4, the tread portion 32 connects each axial groove 36 with an axial groove 36 forming a zigzag shape from one end 32d of the trend portion 32 to the other end 32e approximately in the rotation axis direction R on the outer peripheral surface of the tire. It has an auxiliary groove 37. Further, each axial groove 36 is symmetrical with respect to the tire equatorial plane C, and each axial groove 36 has an inverted ■ shape and has a directional pattern arranged at equal intervals P' in the circumferential direction of the tire. It is.

When such a motorcycle tire runs straight ahead, the ground contact portion of the tread portion 32 with the road surface coincides with the tread center portion 2a having the ground contact edge 38 in FIG.

However, when turning, the motorcycle takes a large camber angle and the vehicle body is tilted, so the part of the trend section 32 that contacts the tread moves, and for example, the center of contact moves from the tire equatorial plane C. The position is 39, which is shifted to the left or right by distance A, and the grounding end is also moved. Therefore, when there is rainwater on the road surface in rainy weather and the driver is driving straight on it, the axial grooves 36 of the conventional tire having the directional pattern τ are formed in the axial direction that is divided into left and right from the equatorial plane C of the tread portion 32. Since the groove 36 exists, the equatorial plane C of the tread portion 32
Drainage performance near the area is effective. However, when turning, as mentioned above, the ground contact part moves,
The center of ground contact moves to position 39.

In this case, the ground contact center 39 has only the axial groove 36 extending outward of the tread portion 32, and there is no axial groove 36 that is divided into left and right sides around the ground contact center 39. Therefore, there is a problem in that the water drainage performance near the ground contact center 39 of the turning tire is greatly reduced, slippage occurs between the tire and the road surface, and running safety is reduced.

(Purpose of the Invention) Therefore, the present invention provides a tire for motorcycles running at high speed that has sufficient drainage performance both when driving straight in rainy weather and especially when driving in turns, while maintaining sufficient steering stability. An object of the present invention is to provide a pneumatic tire having a directional pattern of a tread pattern that greatly reduces the occurrence of slip between the tire and the road surface and provides high running safety.

(Structure of the Invention) A pneumatic tire according to the present invention includes a tread portion, a pair of side tread portions, a pair of bead portions, and a carcass portion consisting of at least one carcass layer. A plurality of zigzag-shaped axial grooves extending along a line substantially parallel to the rotational axis of the tire from one end in the rotational axis direction of the tire to the other end, the plurality of axial grooves extending in the equatorial plane of the tire , and each of the axial grooves has a pair of central diagonal grooves and a pair of outer diagonal grooves, and the pair of central diagonal grooves are connected. The tire has a trough formed at a portion where the central diagonal groove portion and an outer diagonal groove portion are connected, and a peak portion formed at a portion where the central diagonal groove portion and the outer diagonal groove portion are connected, and is formed in an inverted W-shape as a whole with respect to the circumferential direction of the tire. It is characterized by what it did.

(Example) Hereinafter, an example of the present invention will be described based on the drawings. 1st
1 and 2 are views showing one embodiment of a pneumatic tire according to the present invention, and FIG. 1 is a radial cross-sectional view of the pneumatic tire filled with air to a specified amount of air pressure.

First, the configuration will be explained. In Figure 1, 1 is a pneumatic tire for a motorcycle, and the pneumatic tire 1
has a tread portion 2, a pair of side tread portions 3.3', a pair of bead portions 4.4', and a carcass portion 5 having a carcass layer consisting of one layer.A horizontal floor surface. In the above, when a specified load is applied perpendicularly to the horizontal axis of rotation (not shown) of the pneumatic tire,
The tread portion 2 is centered on the equatorial plane E of the tire and is composed of a tread center portion 2a that is in contact with the ground up to both ground contact edges 6, and tread side portions 2b on both sides thereof.

Next, when turning, the motorcycle tire takes a large camber angle, so the ground contact portion of the tread portion 2 moves significantly. Trend when a predetermined maximum camber angle is taken The ground contact center of part 1 2 moves from the equatorial plane E to the sub ground contact center 7 separated by a distance A. FIG. 2 is a partially exploded view of the tread portion 2 of FIG. 1, and is a diagram showing the tread pattern of the second trend portion in the pneumatic tire 1 of the present invention. In FIG. 2, the tread portion 2 is
It has a plurality of zigzag-shaped axial grooves on the outer circumferential surface of the tire along a line substantially parallel to the rotational axis of the tire from one end 2d in the rotational axis direction of the tire (indicated by arrow R) to the other end 2e. .

The plurality of axial grooves 8 are arranged symmetrically with respect to the equatorial plane E of the tire, and at equal intervals P in the circumferential direction of the tire (indicated by arrows). Each interval P in the circumferential direction of the plurality of axial grooves 8 is set in a range of 35 to 55% of the tread width Tw, which is the distance from one end 2d to the other end 2e of the tread portion 2. Each axial groove 8 has a pair of central oblique grooves 8a centered on the equatorial plane E of the tire and a pair of outer oblique grooves 8b on the outside thereof. A trough 11 is formed in the connected portion of the pair of central oblique grooves 8a, and the center of the trough 11 and the tire equatorial plane E coincide. A mountain portion 12 is formed at a portion where the central diagonal groove portion 8a and the outer diagonal groove portion 8b are connected. Each axial groove 8 forms a substantially inverted W-shape as a whole with respect to the circumferential direction of the tire. The pair of outer diagonal grooves 8b extend substantially linearly from the apexes 12a of the pair of peaks 12 inside the tread central portion 2a to both ground contact ends 6, and are bent at both ground contact ends 6, respectively. It is provided within the side portion 2b to one end portion 2d and the other end portion 2e. Reference numeral 13 denotes a first auxiliary groove, and the first auxiliary groove 13 is provided within the circumferential center line of the tire including the equatorial plane E and is spaced apart from the adjacent axial groove 8. 14 is a second auxiliary groove, and the second auxiliary groove 14 is provided between adjacent outer oblique groove portions 8b.

The apexes 12a of the pair of peaks 12 of the axial groove 8 are each
It is located between both ground contact ends 6 of the trend portion 2 in the rotational axis direction when the tire runs straight and the equator E of the tire, and preferably, the distance A between the apex 12a and the equatorial plane E of the tire is equal to the trend width Tw. It is in the range of 10 to 16%. Further, the angle α is an internal angle of the trough 11, and the internal angle α is the center line G4 of each groove of the pair of central diagonal grooves 8a centered on the trough 11.
, the angle formed by G2. The internal angle α is in the range of 95 to 125 degrees, preferably in the range of 105 to 115 degrees. The angle β is between the center lines G 3 and G 4 of the pair of outer diagonal grooves 8b from the pair of peaks 12 to both ground contact ends 6 of the tosifted part 20, and the circumference of the tire parallel to the tire equatorial plane E at both ground contact ends 6. This is the angle formed with direction F. The angle β is in the range from 20 to 40 degrees, preferably from 25 to
The range is 35 degrees. The angle γ is the angle between the center lines G9, G9 of each groove of the pair of outer oblique grooves 8b in the tread side portion 2b and the circumferential direction H at the one end 2d and the other end 2e, and the angle γ is 50 to 80. An angle range of degrees is preferred.

The angle δ is the internal angle of the peak portion 12 of the axial groove 8, that is, the angle formed by the center lines Gt and G2 of the central diagonal groove portion 8a and the center lines G3 and G4 of the outer diagonal groove portion 8b, respectively,
The angle δ is preferably in the range of 70 to 90 degrees.

(Action) Next, the action will be explained. Tires for motorcycles that run at high speeds are required to maintain sufficient handling stability in sunny weather, and in particular, have excellent drainage performance and handling stability in the tread portion during both straight driving and turning driving in rainy weather.

First, we will explain the drainage effect when traveling straight ahead. Second
In the figure, when traveling straight, the tread center portion 2a guides the tread center portion 2a to touch the ground, but the tread center portion 2a has two peaks 12 of the axial grooves 8 on the left and right sides of the equatorial plane E, and the tread center portion 2a Rainwater is divided into the central diagonal groove 8a side and the outer diagonal groove 8b side around the apex 12a of the mountain portion 12, collected in the groove, and flows along the groove. Rainwater flowing along the central diagonal groove portion 8a is collected in the valley portion 11 and drained rearward by rotation of the tire. The internal angle α of the valley portion 11 is in the range of 95 to 125 degrees, but if it is less than 95 degrees, the drainage performance is improved, but the traction performance, which is the braking performance or acceleration performance of the tire, is degraded. Furthermore, if the temperature exceeds 125 degrees, drainage performance during rainy weather will deteriorate. The first auxiliary groove makes it more effective to drain rainwater collected in the trough 11 to the rear of the tire. Further, rainwater in the outer oblique groove portion 8b flows along the groove toward the outside of the tread center portion 2a, and is drained outward at the ground contact edge 6.

At this time, the angle β is 20 to 40 with respect to the circumferential direction F of the tire.
Since the angle is small, drainage of rainwater in the circumferential direction F is extremely effective. If the angle β is less than 20 degrees, the length of the groove from the peak portion 12 to the ground contact edge 6 becomes too long, resulting in a decrease in traction performance. Furthermore, if the angle exceeds 40 degrees, the drainage performance outside the tread center portion 2a will deteriorate. Since the second auxiliary groove 14 connects the peak portion 12 of the outer oblique groove 2b and the ground contact end 6, it further improves the drainage effect of rainwater in the outer oblique groove 2b.

This is especially effective when there is a large amount of rainwater.

Next, the drainage effect during turning will be explained. When the vehicle turns, the tire tilts with a large camber angle, and the tire's ground contact center moves a distance A from the equatorial plane E to the sub-ground contact center 7 at its maximum. At this time, the fixed ground end 6 moves left and right by approximately a distance A in accordance with the movement of the center of ground contact. Therefore, when the vehicle turns in rainwater, the rainwater concentrates on the auxiliary ground contact center 7, which is the ground contact center at this time. Since the ridge portion 12 of the axial groove 8 is located on the sub-ground contact center 7, rainwater in this portion is efficiently divided into the central diagonal groove portion 8a and the outer diagonal groove portion 8b. Center oblique groove part 8
Rainwater a collects in the trough portion 11 and is further efficiently drained to the outside through the gap between the axial groove 8 and the road surface due to centrifugal force. Moreover, the rainwater in the outer diagonal groove part 8b is removed from the grooves in the circumferential direction F and 2.
A small angle of 0 to 40 degrees is an angle at which rainwater can easily flow in the circumferential direction.Furthermore, even in the tread side portion 2b, the direction of the groove is at an angle T of 50 to 80 degrees with respect to the circumferential direction H. Therefore, rainwater in the outer diagonal groove portion 8b is quickly discharged to the outside of the tire. Unlike conventional tires, which have grooves in only one direction at the center of contact,
In the case of the tire of the present invention, concentrated rainwater is divided and diverted by the mountain portions 12, so drainage is extremely effective.
There is no slippage with the road surface.

On the other hand, the outer diagonal groove portion 8b in the tread side portion 2b
The angle γ between the groove center line G and the circumferential direction H is 50 to 80
Since the angle is in the range of 100 degrees, it is an effective angle for traction performance. Furthermore, since the angle formed by the pair of central diagonal grooves is 95 to 125 degrees, traction performance is also sufficiently ensured. The performance test results of a conventional pneumatic tire compared to this are shown at the bottom of the table below as a comparative example. In the examples and comparative examples in the table below, the tire size used was 130/
80-18, and all conditions are the same except for the road surface pattern conditions shown at the top of the following table. In the performance test, the pneumatic tires of the Example and Comparative Example were alternately mounted on the same vehicle, and a comparative test using the actual vehicle was conducted by multiple drivers, and the results are shown as average values. The numerical value is shown as an index with the comparative example as 100, and a larger index indicates better performance. The performance items compared are shown in the table below for performance in rainy weather and performance in sunny weather.

In the following table, the performance of the examples showed superior results compared to the performance of the comparative examples. It has excellent steering stability and braking performance, especially in rainy weather. Furthermore, the tire having the tread pattern of the example exhibits excellent crack resistance against cracks, which are partial defects in the tread portion, that occur in the tread pattern of the tread portion.

(Hereinafter, the margin of this page) (Effects of the Invention) As explained above, according to the present invention, tires for motorcycles running at high speed can be used in rainy or rainy conditions while maintaining sufficient steering stability and braking performance. The water drainage performance is extremely good when driving straight ahead, especially when turning, and there is no slippage with the road surface. Further, it is possible to provide a tire having a directional pattern of a tread pattern, which has excellent crack resistance and high safety without causing cranks in the tread portion.

[Brief explanation of the drawing]

1 and 2 are views showing one embodiment of a pneumatic tire according to the present invention, FIG. 1 is a radial cross-sectional view thereof, and FIG. 2 is a partial development of the tread portion of FIG. 1. It is a diagram. 3 and 4 are diagrams showing an example of a conventional pneumatic retirement tire. FIG. 3 is a radial cross-sectional view thereof, and FIG. 4 is a partially exploded view of the tread portion of FIG. 3. . 2------- Tread part, 3.3'-----Side tread part, 4.4'
-------Bead part, 5--Carcass part, 6-------Grounding part, 8----Uniaxial groove, 8a----Central diagonal groove part, 8b- ----・-Outer oblique groove part, 11------One valley part, 12------One mountain part, α---Inner angle, E------One tire equatorial plane, R・-1111 The rotational axis direction of the tire, L-----1 the circumferential direction of the tire.

Claims (4)

[Claims] (1) In a pneumatic tire having a carcass part consisting of a tread part, a pair of side tread parts, a pair of bead parts, and at least one carcass layer, a line substantially parallel to the rotational axis of the tire is formed on the outer peripheral surface of the tread part. a plurality of zigzag-shaped axial grooves extending from one end to the other end in the rotational axis direction of the tire, the plurality of axial grooves are symmetrical with respect to the equatorial plane of the tire, and troughs arranged at equal intervals in the circumferential direction, each of the axial grooves having a pair of central diagonal grooves and a pair of outer diagonal grooves, and formed at a portion where the pair of central diagonal grooves are connected; 1. A pneumatic tire comprising a peak formed at a portion where a central diagonal groove and an outer diagonal groove are connected, and the pneumatic tire is formed in an inverted W-shape as a whole with respect to the circumferential direction of the tire. (2) The apex of the peak of the axial groove is located between the ground contact end of the tread portion in the direction of the rotational axis and the equatorial plane of the tire when the tire runs straight. The pneumatic tire described in item 1. (3) The angle formed by the internal angle of the valley of the axial groove is 95 to 1
The pneumatic tire according to claim 1, characterized in that the angle is within a range of 25 degrees. (4) The angle between the groove center line of the outer diagonal groove from the peak of the axial groove to the ground contact end and the circumferential direction of the tire is 20 to 40.
2. The pneumatic tire according to claim 1, wherein the pneumatic tire is within a range of .