JPH0648123A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To effectively prevent the occurrence of ribber wear, while holding a zigzag shape of a longitudinal groove. CONSTITUTION:The crest section 5 and the trough section 6 of a rib 3 constituting the side wall 7 of a zigzag longitudinal groove on a tire tread section 1, are formed so that an angle thetaA formed between the ridge line A of the crest section 5 extended from a tread open end to a groove bottom 9, and a vertical plane VS to a tire rotation axis, is smaller than an angle thetaB between the ridge line B of the trough section 6 extended from the tread open end to the groove bottom 9, and the plane VS. Also, the crest and trough sections 5 and 6 of the rib 3 are reversed about the boundary of an intermediate zone 10 extended from the tread open end to the groove bottom 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a rib pattern having a plurality of continuous longitudinal grooves in a zigzag shape in the tire circumferential direction, and particularly to prevention of riverwear occurring at the rib end portion. .

[0002]

2. Description of the Related Art When a radial tire, such as a truck bus or a light truck, is run, it spreads in the tire width direction at the side ends of the ribs located on both sides of the longitudinal groove and forms a river-like structure connected to the tire circumference. Wear may occur. This uneven wear is usually called river wear, but when this develops, the river wear at the ends of the ribs is partially connected in the circumferential direction of the tire, and eventually the entire rib wears one step earlier than other ribs. Rib punch may occur.

Conventionally, various techniques have been proposed in order to prevent this kind of wear. For example, a technique is generally used in which the height of the mountain portion of the groove wall at the rib-side end portion is reduced to reduce the degree of zigzag protrusion. This is because the starting point of the riverwear is in the mountain part of the groove wall where the rigidity is small against the vertical load on the rib, so by reducing this mountain part which is a low rigidity part, the difference in rigidity from the rib center part is reduced. We are trying to prevent uneven wear.

There is also provided a technique of applying a large number of sipes parallel to the tire rotation axis to the crests of the groove walls at the rib-side ends. As a further different method, there is a technique of forming a continuous or intermittent sipe substantially parallel to the vertical groove at a position slightly apart from the rib end along the rib end.

[0005]

However, when the height of the ridge portion of the groove wall at the end portion on the rib side is reduced to form a straight vertical groove, the generation of riverwear can be suppressed, but the edge of the pattern can be suppressed. The effect is lowered, and there arises a problem that the traction performance when driving on a wet road is lowered. In addition, the appearance of a slippery appearance is not preferable because it gives the driver a psychological anxiety. In order to improve this, it is possible to use a lot of sipes. That is, the technique of forming a continuous or intermittent sipe along the longitudinal groove at a position slightly apart from the rib end portion controls the movement of the rib end in the tire width direction, thereby suppressing circumferential slippage and uneven wear. However, even though such a means has the effect of preventing uneven wear, such a means may cause a decrease in steering stability due to a decrease in lateral rib rigidity and a decrease in wear durability due to a decrease in effective wear area. It is easy to induce and may lack practicality.

In addition, the technique of forming sipes on the crests of the groove walls at the rib-side end must form a large number of long and deep sipes in order to obtain the desired effect, which is a design limitation. However, there is a problem that a crack is generated from the sipe end and another uneven wear occurs.

An object of the present invention is to provide a pneumatic tire capable of effectively preventing the generation of riverwear while maintaining the zigzag shape of the vertical groove.

[0008]

[Means for Solving the Problem] By the way, in riverwear, the rib is bent by a vertical load at the time of contact with the ground, which pushes the rib end in the tire width direction, and the slip in the width direction causes friction against the circumferential force when the tire rotates. It is considered that this causes a decrease in the coefficient, and as a result, slippage with the road surface increases. Especially in the case of a tire having a zigzag vertical groove on the tread portion of the tire, the zigzag peak is the base point of the riverwear, but this is caused by vertical load because the distance from the rib center to the rib zigzag peak is longer than the valley. The shearing force on the surface of the tread surface of the rib is correspondingly large, and therefore slippage is likely to occur and wear is likely to occur. Therefore, in order to effectively prevent the riverwear, it is necessary to make the shearing force in the rib width direction generated by the vertical load substantially equal in the peak and the valley while the zigzag of the rib is held.

In this respect, in the conventional zigzag, the rib crest is still a crest at the groove bottom, and the trough is also a trough at the groove bottom, so that the rubber movement difference in the width direction generated between the crest and the trough of the rib becomes large. Since slippage first occurred in the mountain portion having a large value, in the present invention, in order to equalize the shearing force in the rib width direction in the mountain portion and the valley portion in the rib, the rib from the tread tread opening end to the groove bottom. In the middle of the process, the rib peaks and valley peaks and valleys interchange with each other, and at the groove bottom, the peaks of the peaks become valleys, and the valleys of the valleys become peaks, which are the opposite of the opening end.

That is, according to the present invention, a plurality of vertical grooves which are continuous in a zigzag shape in the circumferential direction of the tire tread portion,
In a pneumatic tire having a plurality of ribs sandwiched between the vertical grooves and between the vertical groove and a shoulder ground contact end, a tread portion opening is formed by a mountain portion and a valley portion of the ribs forming the groove wall of the zigzag-shaped vertical groove. The angle θ _A formed by the ridgeline A of the mountain portion extending from the end to the groove bottom and the plane perpendicular to the tire rotation axis is such that the ridgeline B of the valley portion extending from the opening end of the tread tread portion to the groove bottom and the plane perpendicular to the tire rotation axis. The air that is configured to be smaller than the angle θ _B formed by and that is inverted from the crest of the tread tread to the groove bottom, with the rib peaks changing from mountain to valley, and the valley changing from valley to mountain. It is a tire containing.

The angle θ _A formed by the ridgeline A of the rib crest with the plane perpendicular to the tire rotation axis and the angle θ _B formed by the valley ridgeline B with the plane perpendicular to the tire rotation axis are the same as the rib crest. Since it is preferable that the difference in rigidity of the valley is balanced, the angle θ _A of the ridgeline A of the mountain portion is usually 0 to 15 °, and the angle θ _B of the ridgeline B of the valley portion is 8 to 30 °. It is in a preferable range. In terms of cross-sectional shape, it is most preferable that the ridgeline A of the mountain portion intersects the ridgeline B of the valley portion on the groove bottom side with respect to the center of the groove depth of the vertical groove.

In order to further equalize the difference in rigidity between the ridges and the valleys of the ribs, the ridgeline A of the ridges on one of the banks of the vertical groove and the bottom point where the ridgeline A intersects the groove bottom and the other bank It is preferable that a bottom point where the ridgeline B of the valley portion intersects with the groove bottom is located on a plane substantially parallel to a plane passing through the tire rotation axis. This configuration is also preferable in that the zigzag on both banks of the vertical groove becomes parallel on both banks and the groove width can be effectively secured, so that the original drainage of the vertical groove is not hindered.

[0013]

According to the present invention, the angle θ _A formed by the ridgeline A of the ridge extending from the opening end of the tread to the groove bottom and the plane perpendicular to the tire rotation axis is the angle θ _A of the tread tread opening. The rib is configured so that it is smaller than the angle θ _B formed by the ridgeline B of the trough extending from the end to the groove bottom and the plane perpendicular to the tire rotation axis, and the middle region from the opening end of the tread tread to the groove bottom is set as a boundary. Because the pneumatic tire has the peaks of the ribs inverted from the peaks to the valleys and the valleys of the ribs reversed from the valleys to the peaks, the average distance between the rib peaks and the rib centers of the valleys is the same, and The difference in rigidity between the valleys is reduced, and the shearing force in the rib width direction with respect to the vertical load can be substantially equalized.

Therefore, as in the conventional case, the decrease in the frictional force at the peak portion with respect to the vertical load does not increase more quickly than at the valley portion and is averaged. Exhibits the same effect as a groove. Moreover, since the zigzag shape of the vertical groove is maintained, there is no problem that the edge effect of the pattern is lowered or the traction performance is deteriorated when traveling on a wet road, and steering stability can be maintained. In addition, the driver does not feel uneasy.

[0015]

FIG. 1 is a schematic view of a tread pattern showing an embodiment of a pneumatic tire according to the present invention, FIG. 2 is an enlarged plan view of an essential part near a vertical groove in the same embodiment, and FIG. It is a III-III line sectional view.

In the figure, 1 is a tire tread portion, 2 is a vertical groove that is continuous in a zigzag shape in the circumferential direction of the tire tread portion 1, 3 is the vertical grooves 2, 2 and the vertical groove 2 is a shoulder. It is a rib sandwiched by the grounding end 4. 5, 6
Are the peaks and troughs of the ribs forming the groove wall 7 of the vertical groove 2, respectively. In this embodiment, as shown in FIGS. 2 and 3, the peak 5 extending from the tread opening end 8 to the groove bottom 9 is shown. The angle θ _A formed by the ridge A with the plane VS perpendicular to the tire rotation axis is about 10 °, and the angle B formed by the ridge B of the valley 6 extending from the tread opening 8 to the groove bottom 9 with the plane VS perpendicular to the tire rotation axis. θ _B is about 25 °. Theta _A in both sides of the case longitudinal grooves do not have to be the same as theta _B, need not be the same that theta _A and theta _B in front of another longitudinal groove.

Further, as shown in FIG. 3, the rib crests 5 and the troughs 6 have rib crests 5 from troughs to troughs at an intermediate region 10 from the tread surface opening end 8 to the groove bottom 9. The valley portion 6 of the rib is inverted from the valley to the mountain.

Therefore, as a result of equalizing the average distances of the ribs 5 and the valleys 6 from the center of the rib, the rigidity of the peaks 5 is higher and the rigidity of the valleys 6 is lower than in the conventional case. Therefore, the difference in rigidity between the peak portion 5 and the valley portion 6 is reduced, and the shearing force in the rib width direction with respect to the load in the vertical direction can be substantially equalized. As a result, the decrease in the frictional force at the mountain portion 5 with respect to the vertical load does not increase more quickly than at the valley portion 6 and is averaged. Therefore, the zigzag shape is maintained and at the same time, the occurrence of riverwear is prevented. be able to.

As shown in FIG. 2, in the present embodiment, a bottom point A _P where the ridgeline A of the crest 5 intersects the groove bottom 2 and a bottom point B where the ridgeline B of the valley 6 intersects the groove bottom 2. _P and _P are located on a plane passing through the tire rotation axis. Therefore, since the zigzag of the vertical groove 2 becomes parallel and the groove width can be effectively secured, the drainage property inherent to the vertical groove 2 is not impaired.

FIG. 4 is an enlarged perspective view of the main part of the groove wall in the embodiment.

The present invention is not limited to the above embodiment.

[0022]

As described above, the present invention is a pneumatic tire in which zigzag-shaped peaks and troughs have almost the same shear strain under load, and therefore, the traction performance, the braking performance and the apparent slippage. While maintaining the zigzag shape of the vertical groove, which is effective in terms of easiness and the like, it is possible to effectively prevent the occurrence of riverwear whose peak portion is the base point.

[Brief description of drawings]

FIG. 1 is a schematic view of a tread pattern showing an example of a pneumatic tire.

FIG. 2 is an enlarged plan view of an essential part near a vertical groove in the example.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is an enlarged perspective view of a main part of a groove wall in the example.

[Explanation of symbols]

 1 Tire Tread 2 Vertical Groove 3 Rib 4 Shoulder Ground End 5 Crest 6 Valley 7 Groove Wall 8 Tread Open End 9 Groove Bottom 10 Middle Area A Ridge of Mountain B Ridge of Valley

Claims (3)

[Claims] 1. A pneumatic tire having a plurality of vertical grooves that are continuous in a zigzag shape in the circumferential direction of a tire tread portion, and a plurality of ribs sandwiched between the vertical grooves and between the vertical groove and the shoulder ground contact end. In the tire, the angle formed by the ridge line A of the mountain portion extending from the opening end of the tread portion to the groove bottom and the plane perpendicular to the tire rotation axis, the peak portion and the valley portion of the rib forming the groove wall of the zigzag-shaped vertical groove. θ _A is smaller than the angle θ _B formed by the ridgeline B of the trough extending from the open end of the tread tread to the groove bottom and the plane perpendicular to the tire rotation axis, and from the open end of the tread to the groove bottom. The pneumatic tire is characterized in that the rib crests are reversed from the peaks to the valleys and the rib troughs are reversed from the valleys to the peaks at the intermediate range. 2. The pneumatic tire according to claim 1, wherein an angle θ _A of the ridgeline A of the mountain portion is 0 to 15 °, and an angle θ _B of the ridgeline B of the valley portion is 8 to 30 °. 3. A tire rotating shaft having a bottom point at which a ridgeline A of a mountain portion on one bank of both banks of a vertical groove intersects with a groove bottom and a bottom point at which a ridgeline B of a valley portion on the other bank intersects with a groove bottom. The pneumatic tire according to claim 1 or 2, which is located on a plane substantially parallel to a plane passing through.