JP3626300B2 - Pneumatic tire - Google Patents

Description

【００２８】
表１に示すように、深さ方向に傾斜する一端開放のサイプを設けた実施例品１、２のタイヤは、残留横力を大幅に低減でき、車輌の直進安定性を向上しうるのがわかる。
【００２９】
【発明の効果】
本発明は叙上の如く構成しているため、圧縮変形の際、ブロックに法線回りのトルクを発生させることができ、ブロック形状、パターン形状等に実質的に影響を与えることなく、タイヤの残留横力を低減して車輌の直進安定性を大幅に向上しうる。
【図面の簡単な説明】
【図１】本発明の実施形態を示すタイヤの断面図である。
【図２】本発明の実施形態を示すトレッドパターンの展開図である。
【図３】ブロックをサイプとともに、模型的に簡略化して示す斜視図である。
【図４】サイプの効果を説明するブロックの側面図である。
【図５】表１で用いた比較例品のタイヤのトレッドパターンを示す展開図である。
【図６】ブロック形状に基づく残留横力の発生を説明する線図である。
【符号の説明】
２ トレッド
８、８Ａ〜８Ｄ 辺縁
９、９Ａ〜９Ｄ サイプ
１０、１０Ａ〜１０Ｄ ブロックの壁面
Ｂ、Ｂ１ ブロック
Ｓ１ ブロック表面
θ、θａ〜θｂ 傾斜角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire that improves residual stability caused by a tread pattern by improving sipes provided in a block, and improves straight running stability of a vehicle.
[0002]
[Background Art and Problems to be Solved by the Invention]
In a tire, the straight traveling performance of the vehicle may be impaired due to the influence of the internal structure, tread pattern shape, and the like, leading to a single flow phenomenon. The residual lateral force (RCF) of the lateral force retention of the tire is largely related to the straightness of the vehicle. The residual lateral force is caused by various factors such as steering stability, riding comfort, and noise characteristics. It is known that a tread pattern that affects tire performance and internal structures such as a belt layer and a carcass, particularly the outermost belt cord arrangement are involved.
[0003]
In general roads, there is a slope (cant) for drainage from the center of the road toward the shoulder of the road, so when the vehicle travels straight on a straight road, Tend to deviate from the course.
[0004]
Therefore, in order to suppress the single flow phenomenon of the vehicle and improve the straight running stability performance, the residual lateral force due to the internal structure and the lateral force due to the road surface cant are offset, and the occurrence of the residual lateral force due to the tread pattern is suppressed as much as possible. It is hoped that.
[0005]
On the other hand, as a tread pattern used for a pneumatic tire, a block type in which a plurality of blocks are provided on the tread and a rib-block type are widely used because of their excellent wet performance. In this type of pattern, In general, as shown in FIG. 6, for example, a rhombus-shaped block b in which the lateral groove y is inclined with respect to the tire axial direction is employed in order to reduce the impact sound at the time of contact and to reduce noise.
[0006]
However, when the block having this shape is stepped on the road surface, the sharp corner b1 that arrives first is pushed in the advancing direction first, so that the torsional deformation generates, for example, a clockwise torque t. Increases force RCF. In recent years, there is a tendency to make asymmetric patterns to improve noise performance, ground contact, wear resistance, steering stability, etc., but such asymmetric patterns also tend to increase the residual lateral force. This is a cause of deterioration in straight running stability.
[0007]
In view of such a situation, the present inventor has studied to improve the straight running stability by adjusting the residual lateral force without substantially affecting the block shape, the pattern shape, and the like. As a result, when compressive force is applied to a block provided with a certain sipe that is inclined in the depth direction, it is noticed that directionality is imparted to the deformation, and multiple such sipes are used. As a result, it has been found that torque can be generated in the block at the time of compressive deformation to counter the residual lateral force caused by the block shape and the like, thereby reducing the residual lateral force.
[0008]
In addition, as what discloses the sipe which inclines in a depth direction, there exists a thing of Unexamined-Japanese-Patent No. 5-319030 and Unexamined-Japanese-Patent No. 7-40710. However, since each publication is an improvement proposal in a sipe used for the purpose of edge effect for improving road surface grip, each sipe in the block is parallel to each other with the upper edge of the sipe facing the tire axial direction. It will be arranged in Therefore, even if the slopes in the depth direction are given in parallel to each other, such as the latter, the slopes in the depth direction can be added to the sipe in the kick-out area and the sipe in the tread-side area as in the former. Even if they are different from each other, no torque is generated in the block during the compression deformation, and the straight running stability performance cannot be affected.
[0009]
Therefore, in the present invention, the sipe of one end opening whose one end is opened at the block wall surface is inclined in the depth direction, and the direction of the inclination in the depth direction of each sipe arranged in one block is raised on the block surface. Based on the assumption that it is the same around one normal, it is possible to generate torque around the normal in the block during compression deformation, and to substantially affect the block shape, pattern shape, etc. The purpose of the present invention is to provide a pneumatic tire that can reduce the residual lateral force and improve the straight running stability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire in which a tread is provided with a plurality of blocks, the block surface of the block is cut, one end is opened by the wall surface of the block, and the other end is in the block. The sipe is inclined from the block surface toward the bottom of the sipe, and the direction of the inclination toward the block bottom of each sipe arranged in one block is blocked. It is characterized by having the same orientation in the circumferential direction around the normal line raised at the center of gravity on the surface.
[0011]
In the sipe, it is preferable that the inclination angle θ formed with the block surface is in the range of 35 to 70 degrees in order to generate the torque T more effectively, and in order to obtain a uniform torque reliably. The sipe is preferably opened on each wall surface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, the pneumatic tire 1 in this example is a radial tire for a passenger car, and the carcass 6 is turned around the bead core 5 of the bead 4 through the side wall 3 from the tread 2 and the radius of the carcass 6. A belt layer 7 disposed on the outer side in the direction and on the inner side of the tread 2.
[0013]
The carcass 6 is formed of one carcass ply in this example in which organic fiber cords such as polyester are arranged at an angle of 70 to 90 ° with respect to the tire equator C, and the belt layer 7 includes: For example, steel cords and the like are arranged at an angle of 10 ° to 30 ° with respect to the tire equator C. In this example, the cord is formed of two inner and outer belt plies, and the tread 2 is reinforced with a tagging effect. The outermost belt ply is, for example, a left-down road surface cant in the left-hand traffic area such as Japan. The belt ply has a left-up code arrangement.
[0014]
Further, the tire 1 is provided with a plurality of blocks on the tread 2 by arranging a plurality of vertical grooves M extending in the tire circumferential direction and extending linearly, for example, and a horizontal groove Y extending in a direction intersecting the vertical grooves M. For example, a tread pattern of a block type and a rib-block type provided with B is provided.
[0015]
In this example, as shown in FIG. 2, the longitudinal groove M is composed of four longitudinal grooves M1 and M1 on both sides of the tire equator and outer longitudinal grooves M2 and M2. A rib body R extending continuously in the tire circumferential direction is formed between M1. Further, between the tread edge Te and the outer vertical groove M2, an outer block row Br2 in which the blocks B2 divided by the horizontal groove Y2 are arranged in the tire circumferential direction is formed, and the inner vertical groove M1 and the outer vertical groove M2 are arranged. Between the grooves M2, an inner block row Br1 including the blocks B1 divided by the lateral grooves Y1 is formed.
[0016]
The lateral grooves Y1, Y1, Y2, Y2 are inclined and arranged in a substantially S shape from one tread edge Te to the other tread edge Te. Therefore, in this example, the lateral grooves Y1, Y1, Y2, Y2 are asymmetric with respect to the tire equator C. While forming a rib-block type tread pattern, each block surface S2 of the outer block row Br2 is formed in a substantially rectangular shape. Each block surface S1 of the inner block row Br1 has a non-rectangular rhombus shape that surrounds the front and rear edges 8A, 8B facing the horizontal groove Y and the vertical edges 8C, 8D facing the vertical groove M. A plurality of sipes 9 are provided in each diamond-shaped block B1.
[0017]
In the present example, the sipe 9 includes, as schematically shown in FIG. 3, front and rear sipes 9A and 9B having one end opened at the wall surfaces 10A and 10B connected to the front and rear edges 8A and 8B, and a vertical edge 8C. Four sipes 9C and 9D with one end opened by wall surfaces 10C and 10D connected to 8D, and each sipe 9A to 9D terminates the other end within block B1 without crossing each other. . In FIG. 3, in order to explain the sipe 9, the block surface S <b> 1 has a rectangular shape and the slope of each of the wall surfaces 10 </ b> A to 10 </ b> D of the block B <b> 1 is simplified as a model. It has a substantially rhombus shape, and an inclined gradient is given to each of the wall surfaces 10A to 10D.
[0018]
The sipes 9A to 9D are inclined toward the sipe bottom from the upper edge of the sipe opened at the block surface S1, and the sipe 9A to 9D arranged in one block B1 is inclined toward the block bottom. The direction is set to the same direction around one normal line N raised within the block surface S1, in this example, around the normal line N raised from the center of gravity G of the block surface S1.
[0019]
In this way, when the sipe 9 having only one end opened by the wall surface is inclined toward the sipe bottom, as shown in FIG. 4, when a compressive force is applied to the block B1, the inclination angle θ with the block surface S1. Deformation in the direction F that decreases is generated. Accordingly, by applying deformation F in the direction F to the two or more wall surfaces 10 in this example using such sipes 9, the torque T around the normal line N can be freely generated in the block B1.
[0020]
Accordingly, by making the magnitude and direction of the torque T counteract the residual lateral force caused by the block shape and the like shown in FIG. 6, the residual lateral force can be reduced and the straight running stability of the vehicle can be improved.
[0021]
Here, in order to generate the torque T more effectively and uniformly, the sipe upper edges of the front and rear sipes 9A and 9B are moved from the substantially middle length position of the respective edges 8A and 8B toward the center of gravity G. In addition, the upper sipe edges of the side sipes 9C and 9D may be formed from the substantially middle length position of the respective side edges 8C and 8D toward the center of gravity G, thereby minimizing the size of the sipe. Stop and suppress the decrease in block rigidity, strength, etc. At this time, the lengths La to Ld at the sipe upper edges of the sipes 9A to 9D are set to 70% or less, preferably 50% or less of the length to the center of gravity G.
[0022]
In addition, the inclination angles θa to θd formed with the block surface S1 of each sipe 9A to 9D are preferably in the range of 35 to 70 degrees, more preferably 45 to 60 degrees, in order to effectively generate the torque T. And The depths ha to hd of the sipes 9A to 9D from the block surface S1 are about 0.5 to 1.0 times the heights Ha to Hd of the wall surfaces 10A to 10D, and the inclination angles θa to θd. The sipe depths ha to hd may be set differently from each other, but preferably, the inclination angles and sipe depths of the sipes facing each other are substantially equal, and more preferably, the inclination angles θa to θd of the sipes 9A to 9D. , And sipe depths ha to hd are set substantially equal to each other. The sipes 9A to 9D are slit-like narrow grooves having a sipe width of 1.5 mm or less, and the block rigidity is maintained by closing the sipe width at the time of grounding.
[0023]
In this example, the torque T generated by the sipe 9 is countered with the residual lateral force caused by the block, pattern shape, etc. to reduce the residual lateral force. For example, the torque T and the residual lateral force are generated in the same direction. In other words, this sum may be offset with the residual lateral force caused by the internal structure, and the residual lateral force of the entire tire may be reduced to near zero. Thus, since the torque T can be freely generated by sipes, the straight running stability of the vehicle can be improved while maintaining the degree of freedom of design related to the block and the tread pattern.
[0024]
The slope of the wall surface 10 of the block B can be set to the same level as that of the conventional one, and each sipe 9 has a straight arc shape or a zigzag shape depending on requirements, in addition to forming the upper edge thereof in a straight line. You may form with a curve.
[0025]
The sipes 9 are preferably formed on each wall surface 10 of the block B. However, the sipes 9 can be provided only on the two wall surfaces 10 or only on the three wall surfaces 10, and more than two sipes can be provided in one wall surface 10. 9 may be formed.
[0026]
【Example】
A tire having a structure shown in FIG. 1 and having a tire size of 205 / 60R15 was made on the basis of the specifications shown in Table 1, and the residual lateral force (RCF) of each prototype tire was measured. Compared. The residual lateral force was zero when the self-aligning torque was measured using a flat belt type testing machine under the standard conditions of a mounting rim (15 × 6JJ), internal pressure (2.0 kgf / cm ² ), and load load (450 kgf). It is indicated by the value of the lateral force at the time, and the residual lateral force acting on the right side with respect to the traveling direction is positive (+).
[0027]
[Table 1]

[0028]
As shown in Table 1, the tires of Examples 1 and 2 provided with one-side open sipe inclined in the depth direction can greatly reduce the residual lateral force and improve the straight running stability of the vehicle. Understand.
[0029]
【The invention's effect】
Since the present invention is configured as described above, it is possible to generate a torque around the normal line in the block at the time of compressive deformation, without substantially affecting the block shape, pattern shape, etc. The residual lateral force can be reduced and the straight running stability of the vehicle can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire showing an embodiment of the present invention.
FIG. 2 is a development view of a tread pattern showing an embodiment of the present invention.
FIG. 3 is a perspective view schematically showing a block together with sipes as a model.
FIG. 4 is a side view of a block for explaining the effect of sipes.
5 is a development view showing a tread pattern of a tire of a comparative example product used in Table 1. FIG.
FIG. 6 is a diagram for explaining generation of residual lateral force based on a block shape.
[Explanation of symbols]
2 Tread 8, 8A-8D Edge 9, 9A-9D Sipe 10, 10A-10D Wall surface B of block, B1 block S1 Block surface θ, θa-θb Inclination angle

Claims (3)

While cutting the block surface of the block of the pneumatic tire provided with a plurality of blocks on the tread, arranging a plurality of sipes that open at the wall surface of the block and the other end is interrupted in the block,
The sipe extends from the block surface toward the sipe bottom, and a single normal line rising from the block surface toward the block bottom of each sipe arranged in one block. A pneumatic tire with the same orientation in the circumferential direction. The pneumatic tire according to claim 1, wherein the sipe has an inclination angle θ of 35 to 70 degrees with the block surface. 2. The pneumatic tire according to claim 1, wherein the block surface has a non-rectangular polygonal shape surrounded by four or more edges, and the block has the sipe opened on each wall surface. 3. .

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