JP2006027567A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire keeping ground surface pressure of a block tread uniform from a wear initial stage of the tire until a final stage, and ensuring excellent steering stability. <P>SOLUTION: A notch portion 2 cut in toward the inside of a block is formed at an apex angle part Q of the block 1, and the notch portion 2 is extended toward a groove bottom. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that maintains a uniform contact surface pressure of a block tread from the beginning to the end of wear of the tire and ensures excellent steering stability.

  In general, in a pneumatic tire having a block pattern, the contact surface pressure of the block at the time of load application is higher at each apex of the block and in the vicinity thereof than in the central area of the block. Since the lateral force cannot be efficiently transmitted to the road surface, it has been a cause of hindering the improvement of steering stability.

  As countermeasures against such problems, conventionally, the height of a block is changed between an end region and a central region (for example, refer to Patent Document 1), or chamfering is performed on the end of a block (for example, Patent Document 1). 2), there is a proposal to make the radius of curvature of the block surface smaller than the outer contour radius of the entire tread (for example, see Patent Document 3).

However, since all of these proposals are made by changing the shape only to the surface of the block, the effect of uniforming the contact surface pressure is exhibited when it is new, but the effect is reduced as wear progresses. Had.
JP 2003-18211 A International Publication No. WO00 / 50252 JP-A-11-115419

  An object of the present invention is a pneumatic tire which eliminates the conventional problems and maintains the contact surface pressure of the block tread uniformly from the beginning to the end of wear of the tire to ensure excellent steering stability. Is to provide.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire having a large number of blocks on a tread surface, and a notch cut into each vertex of the block toward the inside of the block. In addition to forming a portion, the cutout portion extends toward the groove bottom.

  In the pneumatic tire of the present invention, a notch portion cut toward the inside of the block is formed at each apex portion of the block, and the notch portion is extended toward the groove bottom. The contact surface pressure can be reduced by reducing the rigidity from the block apex portion to the block central region, and the contact surface pressure of the entire block tread can be made uniform. As a result, the tread can efficiently transmit the lateral force to the road surface, so that the steering stability can be improved. In addition, since this notch is formed so as to extend from the block surface toward the groove bottom, it maintains a uniform contact surface pressure of the block even when wear progresses, and provides excellent handling stability. Can be secured.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing an example of a block formed on the tread surface of the pneumatic tire of the present invention, and FIG. 2 is a plan view of the block of FIG.

  The tread surface of the pneumatic tire of the present invention has a large number of blocks having apex corners. However, in the following embodiments, the blocks form a parallelogram in order to simplify the description. The case will be described.

  In FIG. 1, the block 1 is in the form of a parallelogram having two sides A and B at the adjacent block ends, and the apex corners Q of the four corners of the block 1 are cut toward the inside of the block 1. The cutout portion 2 is formed, and the cutout portion 2 is formed to extend toward the groove bottom. The depth D of the notch 2 is preferably 0.4 to 1.0 times the height H of the block 1.

  Thus, by forming the notch 2 in the apex corner Q of the block 1, the rigidity from the apex corner Q of the block 1 to the central area of the block is reduced, and the contact surface pressure at the time of load loading is reduced. The contact surface pressure of the entire tread surface of the block 1 can be made uniform. As a result, the entire tread can efficiently transmit a lateral force to the road surface, so that the steering stability can be improved. In addition, since the cutout portion 2 is formed so as to extend from the block surface toward the groove bottom, excellent steering stability can be ensured even at the stage where wear has progressed.

  In the present invention, the shape of the notch 2 is not particularly limited, but as shown in FIGS. 1 and 2, the notch 2 is formed by two sides T1 and T2 that open outwardly from the vertex P3 inside the block. Good. Thereby, the rigidity from the apex angle portion Q of the block 1 to the central region can be appropriately reduced, and the ground contact surface pressure of the entire tread surface of the block 1 can be efficiently and uniformly maintained.

  Further, the two sides T1 and T2 of the cutout portion 2 may be formed in a straight line shape as shown in the figure, or may be formed in a gentle curve shape. Furthermore, according to the shape of the block 1, the two sides T1 and T2 of the notch 2 can be chamfered.

  In the present invention, two sides A and B adjacent to each other of the block 1 extend from the intersection point P of the lines extending across the opening ends P1 and P2 of the notch 2, and the sides A and B are respectively extended along the sides A and B. The vertex P3 of the notch is located in a parallelogram region S formed by a side defined by a length of 0.15 times the lengths La and Lb of B and the opposite side of these sides; and When the distances a and b (see FIGS. 3 and 4) from the intersection point P to the respective open ends P1 and P2 are 1.0 mm or more and 0.1 or less times the lengths La and Lb of the sides A and B, respectively. Good.

  If the position of the apex P3 of the notch part deviates from this range, the rigidity from the apex part Q to the central area of the block 1 is too low, so that the contact surface pressure of the entire block tread cannot be made uniform and the entire block As a result, the rigidity of the vehicle is lowered and the steering stability is lowered. Further, if the distances a and b are each less than 1.0 mm, the rigidity in the vicinity of the block apex portion Q due to the formation of the notch portion 2 cannot be sufficiently obtained, and the lengths La and Lb of the block ends A and B are 0. If it exceeds 1.times., The rigidity in the vicinity of the apex portion Q will be too low, and it will be difficult to obtain a uniform contact surface pressure on the tread surface.

  FIG. 3 shows an enlarged view of the vicinity of the apex portion Q (lower left end portion of FIG. 2) where the intersection angle of the two sides A and B in the block of FIG. 2 forms an acute angle, and FIG. An enlarged view of the vicinity of the lower right end portion of FIG. 2 is shown.

  In the present invention, more preferably, the angles α1 and α2 formed by the sides A and T1 of the block 1 and the angles β1 and β2 formed by the sides B and T2 shown in FIGS. 3 when the angle θ1 is 90 ° or less as shown in FIG. 3 with respect to the angles θ1 and θ2 formed by B, α1 and β1 <θ1−10 °, and the angle θ2 is 90 as shown in FIG. When it exceeds °, it is preferable to adjust so that α2 and β2 <80 °. By setting in this way, the contact pressure on the tread surface of the block 1 can be made even more effective.

  As described above, the pneumatic tire according to the present invention has a block having apex corners on the tread surface, and a notch is formed in each apex corner of each block. By forming the part to extend toward the bottom of the groove, the ground contact pressure of the block tread surface at the time of load load is made uniform, so that the steering stability is ensured even at the stage where wear has progressed, By adjusting the formation position of the notch and adjusting the inclination angle of the two sides of the notch according to the size of the angle formed by the extension of the two adjacent sides of the block, the contact surface pressure can be made even more uniform. The present invention is preferably applied to a tire in which substantially polygonal blocks are arranged on the tread surface.

  With a tire size of 205 / 55R16 and a tread pattern of FIG. 5, a conventional tire (conventional example A) in which notches are not formed at the four corners of each block in the three block rows in the central area of the tread surface and the depth of the notches The tires of the present invention (Examples A to D) in which the height D was made different from the block height H as shown in Table 1 were produced. In addition, the shape of the notch part in this invention tire was made common.

The steering stability of these five types of tires was evaluated by the following method, and the results are shown in Table 1 by index display with the conventional example 1 as 100. The larger the value, the better.
[Evaluation method of steering stability]
Each tire was filled with an internal pressure of 210 kPa, mounted on a domestic 2000cc class FF vehicle, and run on a test course consisting of an asphalt road surface, and sensory evaluation was performed by five panelists.

表１から、本発明タイヤは、従来タイヤに比較して操縦安定性が向上していることがわかる。

From Table 1, it can be seen that the steering stability of the tire of the present invention is improved as compared with the conventional tire.

  With a tire size of 205 / 55R16 and a tread pattern of FIG. 6, a conventional tire (conventional example B) in which notches are not formed at the four corners of each block in the four block rows on the tread surface, and FIG. The tires of the present invention (Examples E and F) in which notches are formed by changing the values shown in FIG. 4 as shown in Table 1, and chamfering at the front, rear, left and right block ends of each block without forming notches A comparative tire (Comparative Example A) to which (curvature radius: 10 mm) was applied was manufactured. The length of the block end in each tire is La = 32 mm, Lb = 25 mm, the apex angles formed by the block ends shown in FIGS. 3 and 4 are θ1 = 80 °, θ2 = 100 °, and the tire of the present invention. The ratio of the notch depth D to the block height H at D / H = 0.6.

For these four types of tires, the steering stability at the time of a new article and the progress of wear was evaluated by the same method as in Example 1, and the results are shown in Table 2 by index display with the conventional example B being 100. . The larger the value, the better. The evaluation at the time of progress of wear was performed on the tire in a state where the tread surface was worn 30%.

表２から、本発明タイヤは、従来タイヤ及び比較タイヤに比較して、新品時のみならず摩耗進行時においても操縦安定性が向上していることがわかる。

From Table 2, it can be seen that the steering stability of the tire of the present invention is improved not only when the tire is new but also when the wear progresses, as compared with the conventional tire and the comparative tire.

It is a perspective view showing an example of a block in a tread surface of a pneumatic tire by an embodiment of the present invention. It is a top view of the block of FIG. It is a partially expanded view for demonstrating the shape of the notch part formed in the vertex part of the block of FIG. It is a partially expanded view for demonstrating other shapes of the notch part formed in the vertex part of the block of FIG. 1 is a partial plan view showing a tread pattern of a tire adopted in Example 1. FIG. 4 is a partial plan view showing a tread pattern of a tire employed in Example 2. FIG.

Explanation of symbols

1 block 2 notch Q apex

Claims (5)

In a pneumatic tire having a large number of blocks on the tread surface,
A pneumatic tire in which a notch that is cut toward the inside of the block is formed at each apex of the block, and the notch extends toward the bottom of the groove.   The pneumatic tire according to claim 1, wherein a depth D of the notch is 0.4 to 1.0 times a height H of the block.   The pneumatic tire according to claim 1 or 2, wherein the notch is formed by two sides T1 and T2 that open outwardly from the vertex P3 inside the block.   The lengths of the sides A and B along the sides A and B, respectively, from the intersection point P of the two adjacent sides A and B of the block extending across the opening ends P1 and P2 of the notch. A vertex P3 of the notch is located in a parallelogram region S formed by a side defined by a length of 0.15 times the length and the opposite side of each side, and The pneumatic tire according to claim 3, wherein the distances to the open ends P1, P2 are each 1.0 mm or more and 0.1 times or less of the length of each side A, B. The angle α formed by the side A and T1 and the angle β formed by the side B and T2 have the following relationship with respect to the angle θ formed by the two sides A and B of the block, respectively. Pneumatic tire.
(1) When the apex angle θ is 90 ° or less, α, β <θ−10 °
(2) When the apex angle θ exceeds 90 °, α, β <80 °

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