JPH0853004A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To ensure an excellent wet drainage property while restraining pattern noises sufficiently low and further preventing the occurrence of a wandering phenomenon caused by the presence of a rain groove. CONSTITUTION:A pair of peripheral main grooves 1 disposed line symmetrically in relation to the tread center X-X to have a distance between the centers equal to a half of or less than the tread width are provided, while setting at least one of a distance W1 between the inside end edges and a distance W2 between the outside end edges of both peripheral main grooves 1 within the range of x.N<=W1<=x.N+y, x.N-y<=W2<=x.N, where x is the pitch of rain groove, y is the width of rain groove and N is the number of pitches of rain grooves located between the peripheral main grooves. An auxiliary groove 2 bent or inclined to extend circumferentially is provided between both peripheral main grooves. And crossing sub-grooves 3, 4 for affording communication from positions of the respective auxiliary grooves 2 closest to the peripheral main groove 1, and at least one of intermediate positions to peripheral main groove 1 respectively are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a pneumatic tire suitable as an all-season tire for North America, and in particular, it is formed on the road surface while ensuring excellent wet drainage and suppressing pattern noise sufficiently low. The present invention relates to a tread pattern capable of effectively suppressing the occurrence of a wandering phenomenon caused by a rain groove.

[0002]

2. Description of the Related Art As an example of a tread pattern for an all-season tire used in the North American region, as shown in FIG. 6, there are three linear circumferential grooves and one tread shoulder located at each tread shoulder. Some tires are composed of linear circumferential sub-grooves and inclined grooves that are provided so as to extend obliquely between the respective circumferential grooves, and such tires are excellent especially under the action of the circumferential grooves. Wet drainage can be exhibited.

[0003]

By the way, in the prior art, due to the existence of a plurality of linear circumferential grooves, a plurality of linear circumferential grooves extending on the road surface in the traveling direction of the vehicle such as a freeway in California. When the linear rain groove of the book is carved with a pitch of 19 mm, for example, the wandering phenomenon occurs due to the reaction force that the tire receives from the road surface due to the groove side wall of the tire being caught by the groove side wall. There was a problem of doing.

The present invention has been made as a result of studies made to solve the problems of the prior art, and an object of the present invention is to minimize the number of linear circumferential grooves. By specifying those groove edge positions, etc., sufficient wet drainage performance is ensured, and the reaction force in the tire width direction received by the tire due to the rain groove is effectively canceled to effectively generate the wandering phenomenon. It is to provide a pneumatic tire that can be prevented.

[0005]

A pneumatic tire according to the present invention is arranged line-symmetrically with respect to a tread center and is provided with a pair of circumferential main grooves whose center-to-center distance is 1/2 or less of a tread width. At the same time, at least one of the distance W ₁ between the inner edges and the distance W ₂ between the outer edges of the circumferential main grooves is set as follows: x · N ≦ W ₁ ≦ x · N + y x · N−y ≦ W ₂ ≦ x · N x: Rain groove pitch y: Rain groove width N: Number of rain groove pitches located between circumferential main grooves (including rain grooves where inner and outer edges of the circumferential main groove may enter) In addition, an auxiliary groove extending in the circumferential direction in a curved or inclined manner is provided between both circumferential main grooves, and each auxiliary groove is located at a position closest to the circumferential main groove, for example, both ends and at least one of the auxiliary grooves. Circumferential main groove at each intermediate position It has a transverse sub-groove to communicate with.

This will be described more specifically based on the tread pattern shown in FIG. Since the internal reinforcing structure of the tire is similar to that of a general radial tire, its illustration is omitted here.

In this example, a pair of two circumferential main grooves 1 linearly extending in the tire circumferential direction are arranged in line symmetry with respect to the tread center XX, and the centers of the circumferential main grooves 1 are arranged. The distance is set to about 1/3 of the tread width TW,
The distance W ₁ between the inner edges of the circumferential main grooves ₁ is 40 mm. According to this, the distance W ₁ between the inner edges is that the rain groove pitch (x) is 19 mm, the rain groove width (y) is 2.4 mm, and the number of rain groove pitches between the circumferential grooves (N) is 2. In some cases, the condition of x · N ≦ W ₁ ≦ x · N + y, that is, the condition of 38 ≦ W ₁ ≦ 40.2 is satisfied.

Further, here, auxiliary grooves 2 are provided between the two main grooves in the circumferential direction with a tread center XX therebetween, and are curved toward the tread center side so as to extend in the circumferential direction. The positions of the respective auxiliary grooves 2 closest to the circumferential main groove 1, that is, both ends in the figure, are made to communicate with the same circumferential main groove 1 by the respective first transverse sub-grooves 3. Further, substantially the central portion of each auxiliary groove 2 is made to communicate with the same circumferential main groove 1 as communicated by the first transverse auxiliary groove 3 by one second transverse auxiliary groove 4.

[0009]

In this pneumatic tire, sufficient wet drainage can be ensured by providing two pairs of circumferential main grooves 1 and at the same time, due to the presence of the rain groove, the tire receives the impact from the road surface. Forces can be effectively offset as will be described below. In other words, with one circumferential main groove 1, sufficient wet drainage cannot be secured, and the reaction force received by the tire cannot be canceled effectively. On the other hand, when the number of the grooves is three or more, it is difficult to perform the groove arrangement that avoids the rain groove without sacrificing other performance. Further, even if it is possible with a certain size, it becomes difficult when the size is enlarged.

Further, here, by disposing the circumferential main groove 1 symmetrically with respect to the trend center XX, the reaction force generated in the tire can be well balanced, and further, the circumferential main groove 1 Center distance is tread width TW of 1
/ 2 or less, the circumferential main groove 1 has a high contact surface pressure,
By extending in the central region where the contact length is also long, it is possible to obtain an effective wet drainage property and effectively prevent the occurrence of the hydroplaning phenomenon. In contrast,
When the circumferential main groove 1 is provided in a portion exceeding 1/2 of the tread width TW, the hydroplaning phenomenon is extremely likely to occur.

By the way, according to the circumferential main groove 1 in the illustrated example,
The offset of the reaction force received by the tire is that the inner groove edge portion of each circumferential main groove 1 enters into the rain groove G formed on the road surface R as shown in FIG. The inner groove wall 1a of the main groove 1 is a rain groove G
This is done by receiving road surface reaction forces F of the same magnitude, which are directed toward the trend center, by the outer groove walls of, for example, a rain groove pitch (x) of 19.0 mm, a rain groove of Width (y)
Is 2.4 mm, the distance W ₁ between the inner edges of the circumferential main grooves ₁ must satisfy the condition of 19 · N ≦ W ₁ ≦ 19 · N + 2.4, as is clear from the figure. Will be required.

That is, when the distance W ₁ is less than 19 · N, the inner edge of the circumferential main groove 1 does not exist at the position corresponding to the rain groove G, but even if it exists at the corresponding position, Since it is too close to the inner groove wall of the rain groove G and the reaction force due to the groove is not generated, the reaction forces of the left and right grooves cannot cancel each other and wandering occurs. On the other hand, when the distance W ₁ exceeds (19 · N + 2.4), the inner edge of the circumferential main groove 1 is located beyond the rain groove G, and the reaction forces of the left and right grooves are mutually different. Wandering occurs without canceling each other.

Therefore, here, when the inner edge of one of the circumferential main grooves 1 receives a road surface reaction force by the rain groove G, the inner edge of the other circumferential main groove 1 is always As a result, a reaction force having a direction and magnitude that cancels the road surface reaction force acts, and the occurrence of the wandering phenomenon is effectively prevented.

Here, the groove width of the circumferential main groove 1 is such that the groove edge of one main groove does not enter into two adjacent rain grooves G (19−2.4 =) 16.6 mm or less, But 15
It is preferable that the thickness is not more than mm. On the other hand, the groove width is 16.6
When the value exceeds mm, the absolute width of the groove is too wide, which causes damage to the groove wall. Also, when both groove edges are located inside the respective rain grooves, the input to each groove wall becomes large,
The groove wall is severely damaged.

Further, in this tire, between the circumferential main grooves,
By providing the auxiliary groove 2 that is curved or inclined, that is, curved in the drawing and extending in the circumferential direction, the wet drainage performance can be further improved without fear of occurrence of a wandering phenomenon due to the presence of the rain groove G. Yes, again
The generation of impact noise can be effectively suppressed. And this wet drainage property makes the auxiliary groove 2 communicate with the circumferential main groove 1 by the respective transverse sub-grooves 3 and 4, and allows the water in the auxiliary groove to pass through these transverse sub-grooves 3 and 4. This becomes particularly noticeable when the circumferential main groove 1 is made drainable.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a tread pattern showing an embodiment of the present invention. Here, in addition to the above-mentioned part, here, in the tread end side portion of the bidirectional main groove 1, substantially on the extension lines of the respective transverse sub-grooves 3, 4. The first and second inclined grooves 5 and 6 which are open to the circumferential main groove 1 and open to the tread end through the narrowed portion in the vicinity of the tread end. A circumferential auxiliary groove 7 that intersects the inclined groove 5 and has both ends open to the respective second inclined grooves 6
To provide. According to this, the inclined grooves 5 and 6 and the circumferential auxiliary groove 7 can sufficiently secure wet drainage in the tread side area and can avoid the occurrence of rain groove wander, and further, it is sufficient. Snow traction can be obtained by the edge effect. Also, here, two sipes 8 are provided in the block defined by the respective grooves in order to secure a grip on a low μ road surface such as snow and wet.

FIG. 3 is a tread pattern showing another embodiment of the present invention, in which the tread center X is formed between the respective circumferential main grooves formed in substantially the same manner as described above.
An inclined auxiliary groove 2 that extends straight to the right in the drawing intersecting with −X is provided, and upper and lower end portions of each inclined auxiliary groove 2 are formed by respective first transverse sub-grooves 3.
Each of the circumferential main grooves 1 is communicated with each other, and the intermediate portion of each tilt auxiliary groove 2 is communicated with each of the circumferential main grooves 1 by each of the two second transverse sub-grooves 4. . In this example, the distance W ₂ between the outer edges of the circumferential main grooves 1 is set to a range of x · N−y ≦ W ₂ ≦ x · N so that the wandering caused by the presence of the rain groove is caused. Effectively prevent the occurrence of the phenomenon.

FIG. 4 is an explanatory view showing this fact. When the distance W ₂ between the outer edges of the circumferential main groove 1 satisfies the above condition, the distance W ₁ between the inner edges is almost the same as described above. For the same reason, the outer groove walls 1b of the circumferential main grooves 1 are both subjected to the road surface reaction force F of the same magnitude toward the tread end side by the inner groove walls of the rain groove G, and as a result, , The road surface reaction force that the tire receives will be sufficiently offset. Here, when the distance W ₂ is less than (x · N−y), both outer edges of the circumferential main groove 1 cannot be positioned in the rain groove,
On the other hand, when the value exceeds x · N, even if both outer edges of the outer edges are present in the rain groove, the reaction force on the left and right walls cannot be generated at the same time and the wandering still occurs. appear.

Further, also in this tire, excellent wet drainage performance can be ensured under the action of the respective circumferential main grooves 1 described above, and further, the inclination extending between the circumferential main grooves can be ensured. With the auxiliary groove 2 and the transverse sub-grooves 3 and 4, wet drainage can be further improved without fear of occurrence of a wandering phenomenon.

FIG. 5 is a tread pattern showing still another embodiment of the present invention, in which two pairs of circumferential main grooves are provided with inclined auxiliary grooves 2 extending linearly upward to the right. The respective end portions of the inclined auxiliary grooves 2 are communicated with the respective circumferential main grooves 1 by the respective first transverse sub-grooves 3 having a substantially arc shape, and the intermediate portions of the inclined auxiliary grooves 2 are connected to the first transverse sub-grooves. 3 are communicated with the respective circumferential main grooves 1 by two second transverse sub-grooves 4 extending substantially parallel to each other, and also at the tread end side portions of the respective circumferential main grooves 1, the respective transverse sub-grooves. The first and second arcuate widthwise grooves 11 and 12 which are located substantially on the extension lines of 3 and 4 and which open to the circumferential main groove 1 and open to the tread end are provided substantially in parallel, respectively, and Both arc-shaped widthwise grooves 11,
The 12 are communicated with each other by a narrow groove portion 13 and a sipe portion 14 extending in the tire circumferential direction. Here, the narrow groove portion 13 extends in the tire circumferential direction, but since it is discontinuous in the circumferential direction, it does not affect the occurrence of the rain groove wandering phenomenon.

In this example, the sipe 15 extending substantially parallel to the transverse sub-grooves 3 and 4 is provided in the land portion defined by the grooves as described above, and the sipe 15 and the arc-shaped widthwise grooves 11 and 12 are substantially formed. By providing the sipes 16 extending in parallel, a sufficient grip force due to the edge effect can be obtained on a low μ road surface such as wet and snow.

By the way, in this example, the distance W ₁ between the inner edges and the distance W ₂ between the outer edges of the bidirectional main groove 1 are respectively set as follows: xN≤W ₁ ≤xN + y and xNy By setting the range satisfying both conditions of ≦ W ₂ ≦ x · N, the occurrence of the wandering phenomenon due to the presence of the rain groove is more reliably prevented.

Thus, according to the tire of this example, the occurrence of the rain groove wandering phenomenon can be more sufficiently prevented under the action of the circumferential main groove 1 while ensuring excellent wet drainage. And again, the tilt auxiliary groove 2
By the action of the transverse sub-grooves 3 and 4, the wet discharge property can be further improved and the pattern noise can be reduced. On the other hand, the arcuate widthwise grooves 11 and 12 extending from the circumferential main groove 1 to the tread end side are wet drainage,
And functions to ensure snow traction, and
The narrow groove portion 13 and the sipe portion 14 suppress the skidability of the snow, and by partially closing the groove at the sipe portion 14, the generation of a rain groove wander can be avoided.

[Comparative Example] A comparative test on the wet drainage property of the invention tire and the conventional tire, the effect of reducing pattern noise, and the effect of suppressing the occurrence of the wandering phenomenon with respect to the rain groove will be described below.

◎ Test tire A passenger car tire of size 185/70 R 13 with a tread width (TW) of 150 mm.

Invention Tire 1 A tire having the tread pattern shown in FIG.
Those having the dimensional specifications shown in Table 1.

[0027]

[Table 1]

Invention Tire 2 A tire having the tread pattern shown in FIG. 3,
Those having the dimensional specifications shown in Table 2.

[0029]

[Table 2]

Invention tire 3 is a tire having a tread pattern shown in FIG.
Those having the dimensional specifications shown in Table 3.

[0031]

[Table 3]

Conventional tire A tire having a tread pattern shown in FIG.
Those having the dimensional specifications shown in Table 4.

[0033]

[Table 4]

◎ Test method Tires with an internal pressure of 2.0 kgf / cm ² were mounted on an actual vehicle, and under the load condition equivalent to two passengers, the wet drainage property was 80 km / d on a wet road surface with a water depth of 5 mm. The remaining contact area at the time of passing at h and 90 km / h was measured and evaluated, and the reduction effect of pattern noise was evaluated by feeling the vehicle interior noise when coasting at 100 km / h on a straight smooth road. The effect of suppressing wandering was evaluated by feeling the steering wheel response when driving on a freeway in California.

◎ Test Results The results of the above tests are shown in Table 5 as index values with the conventional tire as a control. The larger the index value, the better the result.

[0036]

[Table 5]

[0037]

As is apparent from the above comparative example, according to the present invention, the excellent structure can be obtained by specifying the circumferential main groove itself and the configuration of each groove formed between the circumferential main grooves. Further, it is possible to secure the wet drainage property and suppress the pattern noise to a sufficiently low level, thereby extremely effectively preventing the occurrence of the wandering phenomenon due to the presence of the rain groove.

[Brief description of drawings]

FIG. 1 is a tread pattern showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of how a road surface reaction force is offset.

FIG. 3 is a tread pattern showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram exemplifying another cancellation mode of a road surface reaction force.

FIG. 5 is a tread pattern showing still another embodiment of the present invention.

FIG. 6 is a tread pattern showing a conventional example.

[Explanation of symbols]

1 Circumferential main groove 2 Auxiliary groove 3 1st transverse sub-groove 4 2nd transverse sub-groove 5 1st inclined groove 6 2nd inclined groove 7 Circumferential auxiliary groove 8 Sipe 11 1st arcuate width direction groove 12 2nd arcuate width direction Groove 13 Fine groove part 14 Sipe part 15, 16 Sipe TW tread width W ₁ Distance between inner edges W ₂ Distance between outer edges XX Tread center

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location 7504-3B B60C 11/06 B 7504-3B 11/08 D

Claims (1)

[Claims] 1. A pair of circumferential main grooves, which are arranged in line symmetry with respect to the tread center and have a center-to-center distance of 1/2 or less of the tread width, and between inner end edges of both circumferential main grooves. At least one of the distance W ₁ and the distance W ₂ between the outer edges is expressed as: x · N ≦ W ₁ ≦ x · N + y x · N−y ≦ W ₂ ≦ x · N x; Rain groove pitch y; Rain groove width N: Within the range of the number of pitches of the rain grooves located between the circumferential main grooves, an auxiliary groove extending in the circumferential direction with a curve or an inclination is provided between both circumferential main grooves, and each auxiliary groove has a circumferential main groove. A pneumatic tire provided with a transverse sub-groove that connects a position closest to the groove and at least one intermediate position to the circumferential main groove.