JP2004058889A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely provide anti-heel-and-toe performance even in a comparatively high shoulder block while maintaining high water drain property. <P>SOLUTION: Fringe parts of each tire equatorial face side of a wall face 20f on stepping-on side and a wall face 20k on kicking-out side of the shoulder block 18 are inclined in the direction in which a block basic part side is expanded to increase rigidity in the vicinity of each tire equatorial face side end part of the wall face 20f on stepping-on side and the wall face 20k on kicking-out side. Fringe parts on an outer side in each direction of tire width of the wall face 20f on stepping-on side and the wall face 20k on kicking-out side are inclined in the direction in which the block basic part side becomes narrow to reduce rigidity in the vicinity of an outer part in each direction of tire width of the wall face 20f on stepping-on side and the wall face 20k on kicking-out side and reduce ground contact pressure. Deformation of the whole shoulder block 18 is suppressed by facilitating entry of the shoulder block 18 into the contact ground when it comes into contact with the ground. A degree of progress of wear from a kicking-out end on a tire equatorial face side is effectively suppressed which becomes a problem in the shoulder block 18 owing to these two effects. <P>COPYRIGHT: (C)2004,JPO

Description

また、θｉｎ、及びθｏｕｔの角度を種々変えて実験した結果、５°≦θｉｎ≦１５°、及び−１５°≦θｏｕｔ≦−５°を満足させると、特徴に効果的であることが分かった。
【００５３】
【発明の効果】
以上説明したように、請求項１に記載の空気入りタイヤは上記構成としたので、　高排水性を維持しつつ、比較的背の高いショルダーブロックにおいても、確実に耐ヒール・アンド・トゥ性能を発揮することができる、という優れた効果を有する。
【００５４】
請求項２に記載の空気入りタイヤは上記の構成としたので、踏込側壁面のタイヤ赤道面側端部付近、及び蹴出側壁面のタイヤ赤道面側端部付近の剛性を十分に高めることができる。
【００５５】
また、請求項３に記載の発明は上記の構成としたので、踏込側壁面のタイヤ幅方向外側端部付近、及び蹴出側壁面のタイヤ幅方向外側部付近の剛性を十分に低めることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る空気入りタイヤのトレッドの断面図である。
【図２】ショルダーブロックの斜視図である。
【図３】従来例のタイヤのショルダーブロックの斜視図である。
【図４】比較例のタイヤのショルダーブロックの斜視図である。
【図５】（Ａ）は背の低いブロックの踏み込み時の側面図であり、（Ｂ）は背の低いブロックの接地中央付近での側面図であり、（Ｃ）は背の低いブロックの蹴り出し時の側面図である。
【図６】（Ａ）は従来の背の高いブロックの踏み込み時の側面図であり、（Ｂ）は従来の背の高いブロックの接地中央付近での側面図であり、（Ｃ）は従来の背の高いブロックの蹴り出し直前の側面図であり、（Ｄ）は従来の背の高いブロックの蹴り出し時の側面図である。
【図７】（Ａ）乃至（Ｃ）は、種々の接地形状を示す説明図である。
【符号の説明】
１０　　空気入りタイヤ
１２　　トレッド
１４　　周方向溝
１６　　横溝
１８　　ブロック[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire having a block pattern and having a high effect of suppressing heel-and-toe wear of a shoulder block.
[0002]
[Prior art]
Conventionally, in pneumatic tires with a block pattern, the contact pressure and the degree of wear development from the equatorial side kick-out end where the shearing deformation is large are large, and the contact pressure between the tread end and the kick-out end was the same as before. And uneven wear called heel-and-to wear occurs.
[0003]
When this heel-and-toe wear occurs, not only the appearance deteriorates, but also the gripping ability of the tire decreases.
[0004]
[Problems to be solved by the invention]
In order to suppress the heel-and-toe wear, there has been proposed a method of increasing the rigidity of the block by forming an angle (in a direction extending from the tread surface of the block toward the inside of the tire) of the groove wall on the stepping end side and the kicking end side of the block. However, there is a problem that the drainage performance is reduced due to a decrease in the groove volume in this region.
[0005]
In addition, this method has not always been effective for relatively tall blocks of tires such as trucks and buses.
[0006]
The present invention has been made in consideration of the above-described circumstances, and provides a pneumatic tire that can reliably exhibit heel-and-toe performance even in a relatively tall shoulder block while maintaining high drainage. Is the purpose.
[0007]
[Means for Solving the Problems]
As a result of repeated experiments by the inventor, when comparing the low block and the high block, in the short block, the slip direction near the trailing edge with respect to the road surface is the opposite direction to the tire rotation direction. In the case of a tall block, the slip direction near the kick-out end to the road surface is the same direction as the tire rotation direction, and the slip direction of the kick-out end is different between the short block and the tall block I understood.
[0008]
That is, when the block height is low, as shown in FIG. 5A, the low block 100 at the time of stepping has less bending deformation in the circumferential direction, and as shown in FIG. The low block 100 is compressed by a load from above and deforms into a barrel shape.
[0009]
As shown in FIG. 5C, the low block 100 at the time of kicking out slides near the kicking end in the direction of arrow B with respect to the road surface 102, that is, in the direction opposite to the tire rotation direction (direction of arrow A). Is generated.
[0010]
That is, in the low block 100, heel-and-to wear occurs because the vicinity of the kick-out end slides in the direction opposite to the tire rotation direction.
[0011]
The mechanism of the occurrence of heel-and-toe wear in the low block 100 has been conventionally known.
[0012]
On the other hand, when the block height is high, the block rigidity is relatively reduced as compared with the case where the block height is low. Therefore, as shown in FIG. Bending deformation is large in the circumferential direction as compared with a low block (see FIG. 5A).
[0013]
In addition, in the vicinity of the center in the ground contact surface, the high block 200 is generally deformed into a barrel shape like the low block as shown in FIG. The effect of bending deformation remains.
[0014]
Further, as shown in FIG. 6C, when the tall block 200 is immediately before the kicking, the entire block is inclined, so that the vicinity of the kicking end (the dotted circle A in FIG. 6C) is in the rotation direction ( It bends and deforms so as to protrude in the direction opposite to the direction of the arrow A (in this state, the influence of the circumferential bending deformation at the time of stepping still remains).
[0015]
When the tall block 200 further moves away from the road surface due to the rotation of the tire, as shown in FIG. 6D, the bent portion near the kicking end (the dotted circle A in FIG. 6D) becomes the original. To the road surface 102 in the direction of arrow C (the same direction as the tire rotation direction).
[0016]
It has now been found that high blocks 200 cause heel-and-toe wear due to sliding in the same direction as the tire rotation direction, which is the opposite direction to the sliding of low blocks 100 when kicking out.
[0017]
Then, the inventor diligently studied the block shape in order to suppress local bending deformation near the kick-out end of the block, and reached the present invention.
[0018]
The invention according to claim 1 is a pneumatic tire provided with a plurality of blocks defined by a plurality of circumferential main grooves extending in a tire circumferential direction and a lateral groove crossing the circumferential main groove in a tread, In the outermost block in the tire width direction, the tread side wall surface on the stepping side, and the edge on the tire equatorial surface side of the kicking side wall surface on the kicking side, the block base side expands with respect to the normal line erected on the tread surface. The outer edge of each block in the tire width direction is inclined with respect to the normal line on the tread surface. Parallel to each other, or inclined in a direction in which the block base side becomes narrower.
[0019]
Next, the operation of the pneumatic tire according to claim 1 will be described.
[0020]
First, the edge of each shoulder equator side of the stepping side wall surface on the stepping side and the kicking side wall surface on the kicking side of the shoulder block is inclined in a direction in which the block base side expands with respect to a normal line laid on the tread surface. Thus, the rigidity in the vicinity of the end of the stepping side wall near the tire equatorial plane and in the vicinity of the end of the kicking side wall near the tire equatorial plane can be increased.
[0021]
On the other hand, the outer edge in the width direction of the tire of the stepping side wall surface on the stepping side and the kicking side wall surface on the kicking side of the shoulder block are parallel to the normal line laid on the tread surface, or the block base side becomes narrower. When the shoulder block touches the shoulder block, the rigidity of the stepping side wall surface near the outer end in the tire width direction and the side wall surface near the outer side in the tire width direction can be reduced to reduce the contact pressure. In this case, the shoulder block can easily enter the ground contact surface, thereby suppressing deformation of the entire shoulder block.
[0022]
In the present invention, these two effects make it possible to effectively suppress the degree of wear progress from the tire equatorial plane side kick-out end, which is a problem in the shoulder block.
[0023]
In general, the grounding shape of the pneumatic tire can be roughly classified into three types as shown in FIGS. 5A to 5C, and the grounding length of the shoulder portion is on the in side (tire equatorial plane CL side)> There is a relationship on the out side (outside in the axial direction), and the degree of deformation and wear on the in side (tire equatorial plane CL side) tends to increase. Thus, the wear at the in-side kick-out end can be effectively suppressed.
[0024]
Further, since the base side of the block is not all widened, it is possible to maintain high drainage by the groove.
[0025]
According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the tread side wall surface on the stepping side with respect to the normal line laid on the tread surface and the kickout side wall surface on the kicking side are located on the tire equatorial plane side. When the angle of the edge is θin, 5 ° ≦ θin ≦ 15 ° is set.
[0026]
Next, the operation of the pneumatic tire according to claim 2 will be described.
[0027]
By setting 5 ° ≦ θin ≦ 15 °, the rigidity near the tire equatorial plane end of the stepping side wall surface and the tire equatorial plane side end of the ejection side wall surface can be sufficiently increased, which is preferable.
[0028]
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, each tire has a stepped side wall surface on a stepped side and a kicked side wall surface on a kicked side with respect to a normal line laid on the tread surface. When the angle of the outer edge in the width direction is θout, −15 ° ≦ θout ≦ 5 ° is satisfied.
[0029]
Next, the operation of the pneumatic tire according to claim 3 will be described.
[0030]
By setting -15 ° ≦ θout ≦ −5 °, the rigidity near the outer end in the tire width direction of the stepping sidewall surface and the outer periphery in the tire width direction of the ejection side wall surface can be sufficiently reduced, which is preferable.
[0031]
The negative value of the angle means that the groove bottom is inclined so that the groove bottom side is closer to the block side than the tread side (in other words, the groove width at the groove bottom is greater than the groove width at the groove opening. Inclined in the direction of the larger, so-called reverse taper).
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the pneumatic tire of the present invention will be described with reference to the drawings.
[0033]
As shown in FIG. 1, a pneumatic tire 10 of the present embodiment is a tire for trucks and buses having a tire size of 295 / 75R22.5 (internal pressure 650 kPa), and a tread 12 has a plurality of circumferential main grooves 14. A plurality of rectangular blocks 18 are provided which are defined by the horizontal grooves 16 and form a so-called block pattern.
[0034]
Since the internal structure of the pneumatic tire 10 is a general radial tire structure, the details of the internal structure are omitted.
[0035]
FIG. 2 is a perspective view showing an outermost block (hereinafter, referred to as a shoulder block) 18 in the tire width direction. 2, the direction of arrow A indicates the tire equatorial plane CL side, and the direction of arrow B indicates the tire rotation direction.
[0036]
Here, the shoulder block 18 has an edge on the tire equatorial plane CL side of the stepping side wall surface 20f on the stepping side and an edge on the tire equatorial plane CL side of the kicking side wall surface 20k on the kicking side set up on the tread surface. The block base is inclined with respect to the normal HL in the direction in which the block base side expands.
[0037]
Further, the edge of the shoulder block 18 on the outer side in the tire width direction (the direction opposite to the direction of the arrow A) of the stepping side wall surface 20f and the outer edge on the outer side of the ejection side wall surface 20k in the tire width direction are aligned with the normal HL. Parallel or inclined in the direction in which the block base side becomes narrower.
(Action)
Next, the operation of the pneumatic tire 10 of the present embodiment will be described.
[0038]
Since the edge of the shoulder block 18 on the tire equatorial plane CL side of the stepping side wall surface 20f and the kicking side wall surface 20k is inclined in the direction in which the block base side expands with respect to the normal HL standing on the tread surface, The rigidity near the end of the side wall surface 20f on the tire equatorial plane CL side and the vicinity of the ejection side wall surface 20k near the end on the tire equatorial plane CL side can be increased.
[0039]
On the other hand, the outer edges in the tire width direction of the stepping side wall surface 20f and the kicking side wall surface 20k of the shoulder block 18 are inclined in a direction parallel to the normal HL standing on the tread surface or in a direction in which the block base side becomes narrower. As a result, the stiffness near the outer end of the stepping side wall surface 20f in the tire width direction and the vicinity of the outer side portion of the ejection side wall surface 20k in the tire width direction can be reduced to lower the contact pressure, and the shoulder block 18 comes into contact with the ground. In this case, the shoulder block 18 can be easily inserted into the ground contact surface to suppress deformation of the entire shoulder block 18.
[0040]
In the present invention, these two effects make it possible to effectively suppress the degree of wear progress from the kick-out end on the tire equatorial plane side, which is a problem in the shoulder block 18.
[0041]
Furthermore, the present invention can reliably suppress heel-and-toe wear even when the block height is high.
[0042]
In addition, since the base part side of the shoulder block 18 is not all wide, high drainage can be maintained.
[0043]
Here, it is preferable that 5 ° ≦ θin ≦ 15 ° is satisfied, where θin is the angle of the edge of the stepped side wall surface 20f and the kick-out side wall surface 20k with respect to the normal HL on the tire equatorial plane CL side. .
[0044]
In addition, when the angle of the outer edge in the tire width direction of the stepping sidewall surface 20f and the kick-out sidewall surface 20k with respect to the normal HL is θout, -15 ° ≦ θout ≦ −5 ° may be satisfied. preferable.
(Test example)
In order to confirm the effects of the present invention, tires of a conventional example, a comparative example, and an example to which the present invention was applied were prepared, and a test on heel-and-to wear resistance was performed using an actual vehicle.
[0045]
Conventional tire: As shown in FIG. 3, the tire has a rectangular parallelepiped shoulder block having a circumferential length L of 50 mm, a width W of 32 mm, and a height of 25 mm.
[0046]
Tire of Comparative Example: As shown in FIG. 4, the circumferential length L is 50 mm, the width W is 32 mm, the height is 25 mm, the step side wall surface and the kick-out side wall surface are the respective side edges of the tire equatorial plane, and the tire. The outer edge in the width direction is inclined in the direction in which the base side of the block expands, and has a shoulder block whose inclination angle θin is set to 10 ° and θout is set to 10 °.
[0047]
Example: The shoulder block described in the above embodiment is provided. Note that θin is set to 10 ° and θout is set to −10 °.
[0048]
All the test tires have a tire size of 295 / 75R22.5 and an internal pressure of 650 kPa.
[0049]
In the test, the test tire was mounted on a drive shaft of a vehicle (2D system) and traveled 20,000 km, and the rubber volume of the shoulder block which disappeared due to heel-and-to wear after traveling was measured.
[0050]
The evaluation is represented by an index when the amount of lost rubber of the shoulder block of the conventional example is set to 100, and the smaller the numerical value, the more excellent the heel-and-to wear resistance.
[0051]
The evaluation is as described in Table 1 below, and it can be seen that the tires of the examples to which the present invention is applied have high heel-and-to-wear resistance.
[0052]
[Table 1]

In addition, as a result of experiments with various angles of θin and θout, it was found that satisfying 5 ° ≦ θin ≦ 15 ° and −15 ° ≦ θout ≦ −5 ° was effective for the characteristics.
[0053]
【The invention's effect】
As described above, the pneumatic tire according to claim 1 has the above-described configuration, so that the heel and toe performance can be reliably maintained even in a relatively tall shoulder block while maintaining high drainage. It has an excellent effect that it can be exerted.
[0054]
Since the pneumatic tire according to claim 2 is configured as described above, it is possible to sufficiently increase the rigidity near the tire equatorial plane side end of the stepping side wall surface and the tire equatorial plane side end of the ejection side wall surface. it can.
[0055]
In addition, since the third aspect of the present invention is configured as described above, it is possible to sufficiently reduce the rigidity in the vicinity of the outer end of the stepping side wall in the tire width direction and in the vicinity of the outer side of the ejection side wall in the tire width direction. .
[Brief description of the drawings]
FIG. 1 is a sectional view of a tread of a pneumatic tire according to one embodiment of the present invention.
FIG. 2 is a perspective view of a shoulder block.
FIG. 3 is a perspective view of a shoulder block of a conventional tire.
FIG. 4 is a perspective view of a shoulder block of a tire of a comparative example.
5A is a side view of a short block when stepping on the block, FIG. 5B is a side view of the short block near the center of contact with the ground, and FIG. 5C is a kick of the short block. It is a side view at the time of taking out.
6A is a side view of a conventional tall block when stepping down, FIG. 6B is a side view of the conventional tall block near the center of contact, and FIG. 6C is a side view of the conventional tall block. It is a side view just before kicking out of a tall block, and (D) is a side view at the time of kicking out of the conventional tall block.
FIGS. 7A to 7C are explanatory diagrams showing various grounding shapes.
[Explanation of symbols]
Reference Signs List 10 Pneumatic tire 12 Tread 14 Circumferential groove 16 Horizontal groove 18 Block

Claims (3)

A pneumatic tire including a plurality of blocks on a tread, the blocks being defined by a plurality of circumferential main grooves extending in a tire circumferential direction and a lateral groove crossing the circumferential main groove,
In the outermost block in the tire width direction, the tread side wall surface on the stepping side, and the edge on the tire equatorial surface side of the kicking side wall surface on the kicking side, the block base side expands with respect to the normal line erected on the tread surface. Tilt in the direction
The outermost edge of the block on the outermost side in the tire width direction, on the stepping side wall surface on the stepping side and on the side wall surface on the kicking side in the tire width direction, is parallel to the normal line laid on the tread surface, or is a block. A pneumatic tire characterized by being inclined in a direction in which a base side becomes narrower. When the angle of the edge of each tire equatorial plane side of the stepping side wall surface on the stepping side with respect to the normal line standing on the tread surface and the kicking side wall surface on the kicking side is θin,
The pneumatic tire according to claim 1, wherein 5 ° ≦ θin ≦ 15 ° is set. When the angle of the outer edge in the tire width direction of the stepping side wall surface on the stepping side with respect to the normal line on the tread surface and the kicking side wall surface on the kicking side is defined as θout,
The pneumatic tire according to claim 1, wherein a relationship of −15 ° ≦ θout ≦ −5 ° is satisfied.

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