JPH04224403A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide excellent wet drainage property, suppress the pattern noise, and enhance the maneuvering stability at a dry tread. CONSTITUTION:A pneumatic tire is equipped with slant grooves 2, 3 which are opening at the tread end and extending in the direction mutually separating as a trend from below to above in the front view of the tire being mounted to a car while positioning apart by the pattern center a-a in the tread 1 of the tire. The pattern center a-a is offset to the outer side of the car of the tire in mounted attitude relative to the tread center, which the angle to the tire equator surface of each slant groove 2 extending to the outer side of the car than the pattern center a-a is made greater than that of the slant groove 3 extending to the inner side of the car than the pattern center at least in the tread central division.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a high-performance pneumatic tire that provides excellent wet drainage, suppresses pattern noise to a sufficiently low level, and greatly improves steering stability on dry road surfaces. .

0002

[Prior Art] Conventionally, this type of pneumatic tire was
Based on a so-called directional pattern, which is a combination of circumferential straight grooves and directional inclined grooves, it is common to perform various tunings on the basic pattern depending on the target performance, for example, to emphasize wet performance. In some cases, the groove negative ratio should be increased; if hydroplaning resistance performance is important, the width of the circumferential groove should be increased; and in other cases, if pattern noise is to be reduced to improve interior comfort,
It is widely practiced to reduce the negative ratio of the inclined grooves to reduce pitch noise caused by impact input when the tire is depressed and kicked off. Furthermore, when placing emphasis on steering stability on dry road surfaces, it is recommended to reduce the negative groove ratio of the tread portion located on the outside of the corner to increase the rigidity of the land area in that section, which is particularly important during cornering. is proposed.

0003

[Problems to be Solved by the Invention] By the way, if we focus on pattern noise, there are two types of noise: noise caused by pattern pitch components and high frequency noise around 1 kHz caused by air column resonance of circumferential straight grooves. It is roughly divided into
The former noise can be reduced by suppressing the impact input component at the time of stepping in and kicking out, as in the conventional technology, but the latter noise can be reduced by suppressing the impact input component during stepping and kicking out, as in the conventional technology. Because the grooves play such a large role, it has been virtually impossible to reduce them effectively. In other words, the sound pressure level of air column resonance depends on the groove volume of the circumferential groove.
No matter how small the groove volume is, as long as the circumferential groove penetrates from the stepping side to the kicking side, high frequency noise of around 1kHz will always occur, regardless of whether it is a straight groove or not. Therefore, in order to sufficiently remove the noise, it is necessary to eliminate the circumferential groove, but if the circumferential groove is eliminated without any measures, the hydroplaning resistance performance will be significantly improved. A decline will be inevitable.

[0004] Therefore, in order to omit the circumferential groove and still provide excellent anti-hydroplaning performance, and at the same time to effectively reduce pattern noise, the extending direction of the inclined groove should be brought closer to that of the tire equator line. However, according to this method, it is difficult to impart high rigidity to the land portion defined between the inclined grooves, and the steering stability on dry road surfaces deteriorates.

The present invention advantageously solves the problems of the prior art, and it is possible to remove the circumferential groove from the tread surface and still maintain a high level of wet performance including hydroplaning resistance. It is possible, and
To provide a pneumatic tire that can greatly improve steering stability on dry road surfaces.

[0006]

[Means for Solving the Problems] The pneumatic tire of the present invention has a pneumatic tire that is located on the tread surface part, with the pattern center separated from the pattern center, so that the pneumatic tire is positioned on the tread surface part so as to be arranged from the bottom to the top when viewed from the front when the tire is mounted on a vehicle. , a tire having respective inclined grooves extending in directions that tend to be apart from each other and opening at the tread edge, the pattern center being relative to the tread center;
Offset the tire in the mounting position toward the outside of the vehicle, and adjust the angle of the inclined groove extending toward the outside of the vehicle from the pattern center with respect to the tire equatorial plane, at least in the center area of the tread, toward the inside of the vehicle from the pattern center. It is larger than that of the inclined groove extending in the
Preferably, the offset amount of the pattern center from the tread center is within 25% of the tread width from the tread center, and preferably, each inclined groove portion extending in the tread center area is relative to the tire equatorial plane. The angle is 20 to 75 degrees, more preferably 20 to 45 degrees on the outside of the vehicle from the pattern center, and 5 to 35 degrees, more preferably 15 degrees on the inside of the vehicle from the pattern center. The angle should be in the range of ~25°. It is also preferable that the angle of the inclined groove portion extending in each tread side region with respect to the tire equatorial plane is larger than that in the tread central region and within a range of 50 to 90°, and further, each from each tread edge to 10 to 20 mm of the tread width.
It is preferable that the tread be curved or bent toward the tread end at a position within a range of %. Here, it is even more preferable that the negative rate on the outside of the vehicle from the pattern center is smaller than the negative rate on the inside of the pattern center.

[0007]

[Function] In this pneumatic tire, by removing the circumferential grooves that are continuous in the tire circumferential direction from the tread surface, it is possible to completely prevent the generation of high frequency noise caused by air column resonance. When the tire is viewed from the front, the deterioration of wet performance including hydroplaning resistance can be extremely effectively prevented by the action of the respective inclined grooves at appropriate pitches extending in directions away from each other from the bottom to the top. In addition, pitch noise can be effectively reduced by appropriately selecting the angles of the respective inclined grooves located across the pattern center relative to the tire equatorial plane, at least in the tread center area. be able to.

Furthermore, in this tire, the angle with respect to the tire equatorial plane of the slanted grooves extending from the pattern center to the outside of the vehicle is determined by adjusting the angle of the slanted grooves extending from the pattern center to the inside of the vehicle at least in the tread center area. By making it larger, it ensures excellent wet drainage performance and improves steering stability on dry roads. In other words, in order to improve wet drainage performance, it is effective to reduce the angle of the inclined grooves with respect to the tire equatorial plane, but in relation to pitch noise variation, the number of circumferential pitches and length of the inclined grooves is naturally limited, so if all the inclined grooves are brought close to the tire equatorial plane, the land part rigidity will become too low. Therefore, in this case, the slope groove angle is increased to provide the required land stiffness on the outer side of the vehicle, which has a particularly important effect on handling stability on dry road surfaces, while on the other hand, on the inner side of the vehicle, the slope groove angle is increased. In some areas, the sloped groove angle is reduced to provide the required wet drainage. Here, the circumferential pitch of the inclined grooves and the pitch noise variation are related to each other. If the circumferential pitch is too large, the number of inclined grooves in the tire circumferential direction will decrease, and the effect of the pitch noise variation will be reduced. Therefore, if the circumferential pitch of the inclined grooves is increased in order to increase the rigidity of the land section defined between the inclined grooves, pitch noise will increase.

Furthermore, in this tire, the pattern center is offset from the tread center toward the outside of the vehicle when the tire is mounted, and more preferably, the amount of offset from the tread center is equal to 2 of the tread width.
By setting it within 5%, it is possible to achieve a high level of both steering stability on dry roads and wet drainage performance. This is to improve steering stability on dry roads.
While it is particularly necessary to increase the rigidity of the land area at least 25% of the tread width from the tread center, in order to improve wet drainage performance, it is necessary to install inclined grooves with a small angle to the tire equatorial plane in the tread. This is because it needs to be formed in an area of 50% or more of the width.

[0010] In such a tire, preferably,
The inclination angle of each inclined groove portion extending in the central area of the tread with respect to the tire equatorial plane is 20 to 75 degrees, more preferably 20 to 4 degrees on the outer side of the vehicle from the pattern center.
The range is 5 degrees, and the range is 5 to 35 degrees, more preferably 15 to 25 degrees on the inside of the vehicle from the pattern center.

[0011] If the inclination angle of the outer side of the vehicle is less than 20°, it is difficult to ensure the rigidity of the land part, and it is difficult to ensure the rigidity of the land part.
If the temperature exceeds 100 °C, wet drainage performance generally decreases. However, when wet drainage performance is sufficiently ensured by the inner side of the vehicle, in other words, when the amount of offset of the pattern center is large, it is possible to incline up to 75°, and beyond that, wet drainage performance deteriorates significantly. do. Also, the angle of inclination on the inside of the vehicle is 5.
If the angle is less than 35°, the required land rigidity cannot be achieved unless the pitch of the inclined grooves is widened, and there is a high risk of uneven wear even during normal driving. I can't make it work.

Preferably, in each of the tread side regions adjacent to both sides of the tread center region, the angle of the inclined groove portion extending therein with respect to the tire equatorial plane is greater than that in the tread center region. By doing so, high land part rigidity is ensured, and at the same time, rapid and smooth drainage of water to the sides of the tread is enabled. Furthermore, this means that the angle of those inclined grooves is 5
This is particularly noticeable when the angle is in the range of 0 to 90 degrees.

By the way, the inclined groove extending in each tread side area is curved or curved toward the tread end side at the above angle at a position within 10 to 20% of the tread width from each tread end. In the case of bending, the land portion rigidity of the tread side region can be sufficiently increased without deteriorating wet drainage performance. That is, if it is less than 10%, sufficient rigidity cannot be imparted to the tread side region, and if it exceeds 20%, wet drainage performance is reduced.

More preferably, the negative rate on the outer side of the vehicle from the pattern center is smaller than the negative rate on the inner side of the pattern center, and more preferably in the range of 50 to 80% of the negative rate on the inner side. This provides a suitable balance between wet performance and dry performance. If the outer side negative rate is less than 50% of the inner side negative rate, the drainage performance will be too low in relation to the angle of the inclined groove with respect to the tire equatorial plane, the amount of offset of the pattern center, etc., and if it exceeds 80%, the drainage performance will be too low. , it becomes impossible to secure the required land rigidity.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of a tread pattern showing one embodiment of the present invention. The internal reinforcement structure of the tire is
Since it is similar to that of a general radial tire, illustration is omitted here. In the figure, 1 indicates the tread surface, 2,
3 are formed on the tread surface portion 1 at each side of the pattern center, and extend in directions away from each other from the bottom to the top when viewed from the front when the tire is mounted on a vehicle. Each groove is shown.

In this example, the pattern center a-a is
For the tread center that overlaps the tire equatorial plane x-x,
The tire in the mounting position is offset by a distance t toward the outside of the vehicle, and with respect to the pattern center a-a,
The inclined grooves 2 and 3 located on the inner side and the outer side of the vehicle are formed so as to be shifted in phase by approximately half a pitch from each other in the circumferential direction of the tire.
, 3 are opened at the tread edge, and their lower ends are terminated at the pattern center a-a position. Among these inclined grooves 2 and 3, the angle θ1 with respect to the tire equatorial plane x-x is set to extend toward the outer side of the vehicle in the tread central area 4, although the grooves extend toward the inner side of the vehicle from the pattern center a-a. Preferably, the angle θ1 is in the range of 5 to 35°, and the angle θ2 is in the range of 20 to 75°. The amount of offset of the pattern center aa from the tread center, in other words, the offset distance t is preferably within 25% of the tread width from the tread center.

By the way, in each of the tread side regions 5 and 6 adjacent to both sides of the tread center region 4, the tire equatorial plane
The angle θ3, θ4 with respect to -x is greater than that of the inclined groove portion extending in the central tread region 4, more preferably in the range of 50 to 90°. That is,
If it is less than 50 degrees, it is difficult to impart high rigidity to the land section divided into the tread side areas 5 and 6, and on the other hand, if it exceeds 90 degrees, the slanted grooves 2 and 3 It is difficult to ensure quick and smooth drainage of water.

Further, here, the angles of the respective inclined grooves 2 and 3 with respect to the tire equatorial plane x-x are angles θ1 and θ, respectively.
2 to the angles θ3 and θ4, in other words, the distance s1 from the respective tread ends of the positions where the respective inclined grooves 2 and 3 bend or curve toward the tread ends.
, s2 are within a range of 10 to 20% of the tread width. In this tire, therefore, the tread side areas 5, 6 also have areas corresponding to the respective distances s1, s2.

[0019] Furthermore, the pattern center a-a
It is preferable that the negative rate on the outer side of the vehicle is smaller than the negative rate on the inner side of the pattern center a-a, and more preferably, the negative rate on the outer side is
The negative rate should be in the range of 50 to 80% of the inner negative rate. In addition, in the illustrated example, from the lower end of each inclined groove 2, 3,
Each sipe 7 extends to the other side of the pattern center a-a and is spaced apart from below to above, but whose angle with respect to the tire equatorial plane x-x is much larger than that of each inclined groove. These sipes 7, 8 forming a sipe 8 and extending across the respective inclined grooves 2, 3 result in an improvement in the ground contact properties of the tread central region 1 in particular.

Furthermore, in each of the tread side regions 5, 6, respective auxiliary grooves 9, 10 are formed between the respective inclined groove portions extending therein, and extend substantially parallel thereto. By opening the grooves 9, 10 at the tread ends, wet drainage performance is further improved, and at the same time, in the tread side regions 5, 6,
The large land area divided between the inclined grooves is divided into two parts to eliminate the extreme difference in rigidity between the land areas in the side member areas 5 and 6 and the land area in the center area 1, thereby improving uneven wear resistance. bring about. Regarding drainage, the auxiliary groove 9 on the inside of the vehicle
Further improvement can be achieved by opening the inclined groove 2 as shown in FIG.

[0021] According to the tire constructed as described above, as described above, it is possible to maintain high wet drainage performance, suppress pattern noise to a low level, and greatly improve steering stability on dry road surfaces. I can do it.

FIG. 2 shows a tread pattern showing another embodiment of the present invention, the basic configuration of which is the same as that shown in FIG. and the distance s2 of the tread side section 6 from the tread edge is equal to the distance s1 of the tread side section 5 from the tread edge. This tire can also provide the same effects as those described above.

FIG. 3 shows a tread pattern showing still another embodiment of the present invention, in which the respective inclined grooves 2 and 3 located apart from the pattern center a-a are, in principle, continuous with each other. On the other hand, between those mutually continuous inclined grooves, each of the inclined grooves 2 and 3 is alternately terminated in a mutually discontinuous state without reaching the pattern center aa, and , double inclined groove 2
, 3 alternately in the tire circumferential direction on the opposite side of the pattern center a-a, the distance from the continuous portion on the tread center side to t1
, the distance from the tread center of the continuous portion on the side far from the tread center is t2.

According to this example, by making each of the inclined grooves 2 and 3 continuous in principle, more effective wet drainage becomes possible. Furthermore, by alternately locating the mutually continuous parts on opposite sides of the pattern center a-a, the length of the left and right inclined grooves can be changed, and the interval between the tops of the inclined grooves in the circumferential direction can be changed. This produces a variation effect in noise reduction.

FIG. 4 shows a tread pattern showing another embodiment of the present invention, which has pattern centers a-a.
All of the respective inclined grooves 2, 3 located apart from each other are continuous with each other, and one inclined groove 3 is formed in a straight line from the tread central area 4 without being bent or curved in the tread side area 6. Further, the auxiliary groove 10
is extended to a position near the pattern center a-a. According to this tire, the block rigidity on the outside of the pattern center is higher than that of other examples, so the dry handling performance is particularly excellent. The reason why all the inclined grooves 2 and 3 are made continuous with each other is to compensate for the fact that the outer groove angle is low and the shetting property is low.

[Comparative Example] Comparative tests between the invention tire and the conventional tire regarding dry road handling stability, wet drainage performance, and low pattern noise will be described below. ◎The test tire size is 225/50 R16 and the tread width is 200
mm Tire o Inventive Tire I A tire having a tread pattern shown in FIG.
The groove width of the inclined groove 2 in the tread center area 1 is 8.5.
mm, the angle θ1 is 22°, the groove width of the inclined groove 3 is 8.5 mm, the angle θ2 is 34°, the offset amount t of the pattern center a-a is 16 mm, and the angle θ1 is 22°. The distances s1 and s2 of the bent or curved portion from the tread edge are 30 mm and 2, respectively.
0 mm, inclined grooves 2, in the tread side areas 5, 6;
The groove widths of grooves 3 and 3 are both 9.0 mm, the angles θ3 and θ4 are 63° and 72°, respectively, and the groove widths of the respective auxiliary grooves 9 and 10 are 8.0 mm and 5.0 m.
m, the negative rate on the inside side of the vehicle from pattern center a-a is 33%, the negative rate on the outside side is 21%, the total negative rate is 28%, and Sipe 7
, 8 with a width of 0.7 mm o Invention Tire II A tire having a tread pattern shown in FIG. 22°, inclined groove 3
The groove width is 8.5 mm, the angle θ2 is 34 degrees, the offset amount t of pattern center a-a is 32 mm, the distances s1 and s2 from the tread edge are each 30 mm, and in the tread side areas 5 and 6, The groove width of inclined grooves 2 and 3 is 9.0 mm, and the angles θ3 and θ4 are 63 mm, respectively.
° and 72°, and the respective auxiliary grooves 9,
10, the groove widths were 8.0 mm and 5.0 mm, and the negative rate on the inside side of the vehicle was 33% and the negative rate on the outside side was 18% o Invention Tire III Tread pattern shown in Figure 3 A tire having
The width and angle of each groove are the same as those shown in FIG. 1, and the distances t1 and t2 from the tread center are 30 mm and 46 mm, respectively.O Invention Tire IV A tire having a tread pattern shown in FIG. hand,
The groove width of the inclined groove 2 in the tread center area is 8.5.
mm, angle θ1 is 22°, groove width of inclined groove 3 is 4.0
mm, the angle θ2 is 63°, and the width of the auxiliary groove 10 is 9.
0 mm, the offset amount t is 35 mm, the inner side negative rate is 29%, and the outer side negative rate is 17% o Conventional tire Tire with the tread pattern shown in Figure 5

0027
]◎Test method Tires filled with the regular internal pressure according to the JIS standard are mounted on an actual vehicle, and under the load condition (70% of the JIS regular load) with two passengers on board, the steering stability on dry road surfaces is The wet drainage performance was evaluated based on the overall feeling of the test driver during various driving on the circuit.
The vehicle speed at which the hydroplaning phenomenon occurs was measured and evaluated when driving straight on a wet road surface of 1.5 mm, and the low pattern noise was evaluated by feeling the noise inside the vehicle when driving at 100 to 40 km/h on a smooth road surface. .

◎Test Results These test results are shown in the following table using indexes. Note that the index value is expressed with the test result of the conventional tire set as 100, and the larger the index value, the better the result.

[Table 1] According to Table 1, it is clear that all of the invented tires can advantageously improve the steering stability on dry road surfaces while maintaining sufficient wet drainage performance. It is clear that a reduction in pattern noise can also be achieved in Tires I to III.

[0029]

Thus, according to the present invention, it is possible to effectively improve the steering stability on a dry road surface while ensuring wet drainage performance and low pattern noise.

[Brief explanation of the drawing]

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

FIG. 2 is a tread pattern showing an embodiment of the invention.

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

FIG. 4 is a tread pattern showing an embodiment of the invention.

FIG. 5 is a tread pattern showing a conventional example.

[Explanation of symbols]

1 Tread tread portions 2, 3 Inclined grooves 4 Tread center areas 5, 6 Tread side areas 7, 8 Sipe 9, 10 Auxiliary grooves θ1, θ2, θ3, θ4 Angle t Offset amount s1, s2 Distance a-a Pattern center x -x Tire equatorial plane

Claims (6)

[Claims] Claim 1: A plurality of patterns are located on the tread surface part, apart from the pattern center, and extend in a direction that tends to move away from each other from the bottom to the top when viewed from the front when the tire is mounted on a vehicle. The tire is provided with inclined grooves that open at the ends of the tread, the pattern center being offset from the tread center to the outside of the vehicle when the tire is mounted,
A pneumatic chamber in which the angle of the inclined grooves extending outward from the pattern center with respect to the tire equatorial plane is larger than that of the inclined grooves extending towards the inner side of the vehicle from the pattern center, at least in the central region of the tread. tire. [Claim 2] The amount of offset of the pattern center from the tread center is calculated from the tread center.
The pneumatic tire according to claim 1, wherein the pneumatic tire has a width within 25% of the tread width. 3. The angle of each inclined groove portion extending in the central area of the tread with respect to the tire equatorial plane is 20 to 75 degrees on the outside of the vehicle from the pattern center, and 5 to 35 degrees on the inside of the vehicle from the pattern center. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire is in the range of . 4. In each of the tread side regions adjacent to both sides of the tread central region, the angle of the inclined groove portion extending in each of them with respect to the tire equatorial plane is within a range of 50 to 90°. Claims 1 to 3
Pneumatic tires listed in any of the above. 5. Each of the inclined grooves is curved or bent toward the tread end at a position within 10 to 20% of the tread width from the respective tread end. Pneumatic tires listed in. 6. The pneumatic tire according to claim 1, wherein the negative ratio on the outside of the vehicle from the pattern center is smaller than the negative ratio on the inside of the pattern center.