JP5330820B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of preventing problems such as circumferential belt breakage and separation between the circumferential belt and the crossing belt while maintaining the rigidity of the belt.

  In a pneumatic tire, particularly a super flat tire, a circumferential belt and a crossing belt are often provided in order to maintain the shape and ensure durability. Here, the crossing belt has high shear rigidity and is easy to extend, and the circumferential belt has low shear rigidity and is difficult to extend.

  Therefore, when the pneumatic tire is grounded and receives a load from the road surface, the crossing belt extends, but the circumferential belt cannot follow the growth of the crossing belt, the circumferential belt breaks, or the circumferential belt and the crossing belt separate. There was a problem that caused. In order to solve this problem, conventionally, measures have been taken such as reducing the width of the crossing belt to reduce shear rigidity, or reducing the width of the circumferential belt to facilitate elongation. However, with these measures, since the rigidity of the entire belt is lowered, there is a possibility that the steering stability of the vehicle is lowered and the uneven wear of the tire is progressed.

Then, cushion rubber is interposed between the circumferential belt and the crossing belt to reduce the influence of the circumferential belt and the crossing belt on each other (for example, see Patent Document 1). .
JP 2005-313837 A

  However, in the pneumatic tire described in Patent Document 1 described above, when a plurality of crossing belts are formed, the width dimension of the specific crossing belt is larger than the width dimension of the crossing belt adjacent to the outside in the radial direction. Since it is set to be large, there is a problem that the cushion rubber increases the thickness of the end portion in the tire width direction of the tread portion, and heat is easily generated during traveling.

  Then, the objective of this invention is providing the pneumatic tire which can prevent troubles, such as a piece of a circumferential belt and a separation of a circumferential belt and a crossing belt, suppressing the thickness of a tread part. is there.

  A first feature of the present invention is that a carcass (carcass 2) that connects a pair of bead cores spaced apart in the tire width direction in a toroidal shape, and a tire radial direction outer side of a top portion (top portion 2a) of the carcass, A circumferential belt having a plurality of cords along the circumferential direction (circumferential belt 3) and a plurality of layers arranged on the outer side in the tire radial direction of the circumferential belt, and inclined with respect to the tire circumferential direction to cross each other The cross belts having the cords (the first cross belt 4 and the second cross belt 5) and the outer end portion in the tire width direction are disposed, and the front end portion in the width direction is inserted between the circumferential belt and the cross belt. And a width dimension (width dimension W2) along the tire width direction of a belt disposed on the outermost side in the tire radial direction among the plurality of crossed belts. The width of the belt adjacent to the inner side in the tire radial direction (width dimension W1) is set to be larger than the width dimension of the circumferential belt (width dimension W3). The width dimension (width dimension W1) along the tire width direction of the belt arranged at the innermost side in the tire radial direction is set smaller than the width dimension (width dimension W2) of the belt adjacent to the outer side in the tire radial direction of the belt. Is the gist.

  According to the first feature, the width dimension of the belt disposed on the outermost side in the tire radial direction is larger than the width dimension of the belt adjacent to the inner side in the tire radial direction and larger than the width dimension of the circumferential belt. The dimensions are set. Further, the width dimension of the belt disposed on the innermost side in the tire radial direction is set smaller than the width dimension of the belt adjacent to the outer side in the tire radial direction of the belt. Accordingly, a gap having a substantially triangular cross section is formed at the end portion in the tire width direction of the belt disposed on the outermost side in the tire radial direction, the belt disposed on the innermost side in the tire radial direction, and the circumferential belt. By storing cushion rubber in this gap, cushion rubber can be efficiently disposed, and at the same time, the total gauge (diameter thickness dimension) at the tire width direction end of the tread portion can be kept small. it can. Moreover, by setting the width dimension of the adjacent belt large, deformation of the tread portion when the pneumatic tire is grounded can be suppressed, and the wear distribution on the tread surface becomes uniform in the tire width direction. Further, since the deformation movement of the tread portion at the time of grounding becomes uniform, the movement in the groove in the tread pattern becomes uniform, and the occurrence of cracks in the groove bottom can be suppressed.

  In other features, the crossing belt is divided into a first crossing belt (first crossing belt 4) disposed on the inner side in the tire radial direction and a second crossing belt second crossing adjacent to the outer side in the tire radial direction of the first crossing belt. Belt 5), the width dimension (width dimension W2) of the second crossing belt is larger than the width dimension (width dimension W1) of the first crossing bell, and the width dimension (width) of the circumferential belt. And the width dimension (width dimension W1) along the tire width direction of the first crossing belt is set smaller than the width dimension (width dimension W3) of the circumferential belt. To do.

  In other features, the crossing belt is divided into a first crossing belt (first crossing belt 4) disposed on the inner side in the tire radial direction and a second crossing belt (second side) adjacent to the outer side in the tire radial direction of the first crossing belt. The width dimension W1 of the first crossing belt is set to be 10 to 50 mm smaller on one side in the tire width direction than the width dimension W2 of the second crossing belt, and is the largest width dimension among the crossing belts. The gist is that the width dimension (width dimension W2) of the large belt is set to 80% or more with respect to the maximum width W4 in the cross section in the tire width direction of the carcass (carcass 2).

  According to the pneumatic tire of the present invention, it is possible to prevent problems such as the circumferential belt being cut and the separation between the circumferential belt and the crossing belt while suppressing the thickness of the tread portion.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

<Schematic configuration of pneumatic tire>
FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention.

  The pneumatic tire 1 according to the present embodiment is disposed on the outer side in the tire radial direction of a carcass 2 that connects a pair of bead cores spaced apart in the tire width direction in a toroidal shape, and the top portion 2a of the carcass 2 along the tire circumferential direction. A circumferential belt 3 having a plurality of cords, and cords arranged in two layers (a plurality of layers) on the outer side in the tire radial direction of the circumferential belt 3 and intersecting each other at a predetermined angle with respect to the tire circumferential direction. The first crossing belt 4 and the second crossing belt 5 that are provided, and a cushion that is disposed at the outer end portion in the tire width direction, and the front end portion in the width direction is inserted between the circumferential belt 3 and the second crossing belt 5 Rubber 6 is provided.

  Further, the circumferential belt 3, the first crossing belt 4 and the second crossing belt 5 are covered with a coating rubber CG. And the surface 10a of the tread part 10 is formed substantially flat along the tire width direction, and the tread part 10 and the side wall part 11 on the side surface of the tire are formed by the tread rubber TG and the side wall rubber SG, respectively. The cushion rubber 6 is formed in a substantially trapezoidal cross section gradually tapering toward the inner side in the tire width direction, the inner side surface 6a extending in the tire radial direction is in contact with the outer end in the width direction of the first crossing belt 4, The upper surface 6b and the lower surface 6c extending in the tire width direction are in contact with the lower surface of the second crossing belt 5 and the upper surface of the circumferential belt 3, respectively.

  The circumferential belt 3 is preferably one in which the cord constituting the belt is wavy or zigzag and extends in the circumferential direction, or the cord constituting the belt is low elastic.

<Relationship between width dimensions of each belt>
FIG. 2 is a schematic diagram showing the magnitude relationship of the width dimensions of each belt in FIG.

  W1 to W4 shown in FIG. 2 indicate the width dimension along the tire width direction, W1 is the width dimension of the first crossing belt 4, W2 is the width dimension of the second crossing belt 5, and W3 is the circumferential belt 3. The width dimension of W4 and W4 indicate the maximum width of the carcass 2 along the tire width direction.

  Thus, the width dimension W2 of the 2nd crossing belt 5 arrange | positioned at a tire radial direction outermost side is larger than the width dimension W1 of the 1st crossing belt 4 adjacent to a tire radial direction inner side. The width W2 of the second crossing belt 5 is set larger than the width W3 of the circumferential belt 3.

  Further, the width dimension W1 of the first crossing belt 4 adjacent to the outer side in the tire radial direction of the circumferential belt 3 is set smaller than the width dimension W3 of the circumferential belt 3.

  Furthermore, the width dimension W1 of the first crossing belt 4 is set to be 10 to 50 mm smaller than the width dimension W2 of the second crossing belt 5 on one side in the tire width direction. That is, the difference in the width dimension between the first crossing belt 4 and the second crossing belt 5 on one side in the tire width direction is (W2−W1) / 2, and this value is set in the range of 10 to 50 mm.

  Further, when the width dimension of the circumferential belt 3 is W3, the relationship between the width dimensions is set to W1 ≦ W3 ≦ W2. Here, when the inside of the pneumatic tire 1 is filled with air, the elongation of the radial dimension at the end of the circumferential belt 3 is preferably 0.3% or less.

  The width dimension W2 of the second intersection belt 5 having the largest width dimension among the intersection belts is set to 80% or more with respect to the maximum width W4 in the cross section in the tire width direction of the carcass 2.

<Operation effect>
(1) In the present embodiment, the width dimension W2 of the second crossing belt 5 disposed on the outermost side in the tire radial direction is larger than the width dimension W1 of the first crossing belt 4 adjacent on the inner side in the tire radial direction, and in the circumferential direction. The width is set larger than the width dimension W3 of the belt 3. Accordingly, a gap having a substantially triangular cross section is formed at the ends of the second crossing belt 5, the first crossing belt 4 and the circumferential belt 3 in the tire width direction. By storing and arranging the cushion rubber 6 in the gap, the cushion rubber 6 can be arranged efficiently, and the total gauge (diameter thickness dimension) at the tire width direction end of the tread portion 10 is also reduced. Can be suppressed. Also, by setting the width dimension W2 of the second crossing belt 5 to the maximum, deformation of the tread portion 10 when the pneumatic tire 1 is grounded can be suppressed, and the wear distribution of the tread surface 10a is in the tire width direction. Becomes uniform. Further, since the deformation movement of the tread portion 10 at the time of grounding becomes uniform, the movement in the groove in the tread pattern becomes uniform, and the occurrence of cracks at the groove bottom can be suppressed.

  Conventionally, by interposing a cushion rubber between the circumferential belt and the crossing belt, the influence of the circumferential belt and the crossing belt on each other is alleviated to prevent circumferential belt breakage and separation. It was. However, the cage thickness in the tread portion is increased by the thickness of the cushion rubber, and there are problems such as heat generation of the tire due to running and an increase in the weight of the tire due to the cushion rubber. Is resolved.

  (2) In this embodiment, the width dimension W1 of the first crossing belt 4 adjacent to the outer side in the tire radial direction of the circumferential belt 3 is set smaller than the width dimension W3 of the circumferential belt 3. As a result, a gap is formed between the circumferential belt 3 and the first crossing belt 4, so that the cushion rubber 6 can be easily housed and arranged.

  (3) The width dimension W1 of the first crossing belt 4 is set to be 10 to 50 mm smaller than the width dimension W2 of the second crossing belt 5 on one side in the tire width direction. That is, the difference in the width dimension between the first crossing belt 4 and the second crossing belt 5 on one side in the tire width direction is (W2−W1) / 2, and this value is set in the range of 10 to 50 mm. When this value is less than 10 mm, the outer ends in the tire width direction of the first crossing belt 4 and the second crossing belt 5 are too close to each other, and the strain generated at the outer end in the tire width direction becomes large. There is a possibility that separation occurs between the first crossing belt 4 and the second crossing belt 5. If this value exceeds 50 mm, the rigidity of the first crossing belt 4 becomes too small, which may cause uneven wear and deteriorate steering stability.

  The width W2 of the second crossing belt 5 having the largest width among the crossing belts is set to 80% or more with respect to the maximum width W4 in the cross section of the carcass 2 in the tire width direction. When this value is less than 80%, the belt rigidity at the shoulder portion between the tread portion 10 and the sidewall portion 11 on the side surface of the tire becomes small, and therefore there is a risk of causing uneven wear at the shoulder portion.

  (4) When the width dimension of the said circumferential belt 3 is set to W3, the magnitude relationship of each width dimension is set to W1 <= W3 <= W2. When W3 is larger than W2, the cross belts 4 and 5 have lower shear rigidity than the circumferential belt 3, so that the cross belts 4 and 5 are less likely to be damaged and the durability is lowered. On the other hand, when W3 becomes smaller than W1, the load input from the cross belts 4 and 5 to the circumferential belt 3 increases, the cord of the circumferential belt 3 is cut, or the circumferential belt 3 and the cross belts 4 and 5 Separation may occur between them. From the above, it is preferable to set the size relationship of each width dimension to W1 ≦ W3 ≦ W2.

[Other embodiments]
It should not be understood that the descriptions and drawings which form part of the disclosure of the above-described embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in each of the embodiments described above, the crossing belt is described as having two layers, but it may be set to three or more layers. In such a case, the width dimension along the tire width direction of the belt arranged on the outermost side in the tire radial direction among the multiple layers of crossing belts is larger than the width dimension of the belt adjacent to the inner side in the tire radial direction of the belt, and It is set larger than the width dimension of the circumferential belt. Moreover, the width dimension along the tire width direction of the belt arranged in the tire radial direction innermost side among the multiple layers of crossing belts is set smaller than the width dimension of the circumferential belt.

  Hereinafter, the present invention will be described in more detail through examples.

The pneumatic tires according to Conventional Examples 1 and 2, Comparative Example 1, and Invention Examples 1 to 3 all have tire sizes of 495 / 45R225. Table 1 shows values such as the width dimension of the circumferential belt and the crossing belt of each tire.

  Here, in the pneumatic tires according to Conventional Examples 1 and 2, Comparative Example 1, and Invention Example 1, the crossing belt has only two layers as described with reference to FIG. In such a pneumatic tire, the crossing belt has a three-layer structure as shown in FIG. That is, the structures of the pneumatic tires according to Conventional Examples 1 and 2, Comparative Example 1, and Invention Example 1 have the dimensional relationship shown in FIG. 2, but in the pneumatic tires according to Invention Examples 2 and 3, A first crossing belt 4, a second crossing belt 5, and a third crossing belt 7 are laminated from the radially inner side to the outer side to form a three-layer structure. Further, as shown in FIG. 3, the width dimension of the first crossing belt 4 is W1, the width dimension of the second crossing belt 5 is W2, the width dimension of the third crossing belt W4, and the width dimension of the circumferential belt 3 W3. Further, the “radial direction difference between the widthwise end of the circumferential belt and the crossing belt” in Table 1 is, for example, that the width of the first crossing belt 4 is larger than the width of the circumferential belt 3 in Conventional Example 1. Therefore, the radial direction difference between the circumferential belt 3 and the first crossing belt 4 is shown. Further, in Example 1 of the present invention, the first crossing belt 4 is narrower than the circumferential belt 3 and the width of the second crossing belt 5 is wider than the circumferential belt 3. 3 and the second crossing belt 5 is the radial difference between the widthwise end of the circumferential belt and the crossing belt.

  Further, the following test was performed in a state where the pneumatic tire described above was assembled to a rim wheel having a width of 17 inches and the air pressure inside the tire was set to 900 kPa as an internal pressure.

(A) Durability After running the pneumatic tire for 100,000 km with a drum at a load of 8500 kg and a speed of 80 km / hour, the separation length index between belts, the number of cords in the circumferential belt, and the heat generation durability index were detected. . These indices are relative to Conventional Example 1, with the value of Conventional Example 1 being 100. Note that the smaller the cord breakage index of the circumferential belt and the cord breakage index of the circumferential belt, the better. The larger the heat generation durability index, the better.

(B) Steering stability Relative feeling of the conventional example 1 as 100 when the pneumatic tire is mounted on the drive shaft of the tractor head and the slalom running is performed with the trailer loaded with a constant load. The feeling index is shown as a good index. In addition, it is so favorable that a feeling index is large.

(C) Uneven wear property When the pneumatic tire is mounted on the drive shaft of the tractor head and an unloaded trailer is pulled to travel 50,000 km, the tread rubber is unevenly worn at the end of the tread in the tire width direction. Was shown as the partial wear vol index. Note that the smaller the uneven wear vol index, the better.

(D) Groove bottom cracking property An initial crack having a depth of 1 mm and a length of 2 mm is provided along the groove bottom of the pneumatic tire, and the drum is run at 50,000 km under the condition of a load of 6500 kg and a speed of 60 km / hour. The growth length of the crack after this is indicated by an index. In addition, the smaller the groove bottom crack propagation index, the better.

  From the above results, it was found that Examples 1 to 3 of the present invention were superior to Conventional Examples 1 and 2 in all items of durability, steering stability, uneven wear, and groove bottom cracking properties.

1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention. It is the schematic which shows the magnitude relationship of the width dimension of each belt of FIG. It is the schematic which shows the magnitude relationship of the width dimension of each belt in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 2 ... Carcass 2a ... Top part 3 ... Circumferential belt 4 ... 1st crossing belt 5 ... 2nd crossing belt 6 ... Cushion rubber

Claims (2)

A carcass that connects a pair of bead cores spaced apart in the tire width direction in a toroidal shape;
A circumferential belt disposed on the outer side in the tire radial direction of the top of the carcass and having a plurality of cords along the tire circumferential direction;
A cross belt disposed in a plurality of layers on the outer side in the tire radial direction of the circumferential belt, and having cords that are inclined with respect to the tire circumferential direction and crossed with each other;
It is arranged at the outer end portion in the tire width direction, and the front end portion in the width direction includes a cushion rubber inserted between the circumferential belt and the crossing belt,
The crossing belt is composed of a first crossing belt disposed on the inner side in the tire radial direction and a second crossing belt adjacent to the outer side in the tire radial direction of the first crossing belt,
The width dimension W1 along the tire width direction of the first crossing belt is set to be 10 to 50 mm smaller on one side of the tire width direction than the width dimension W2 along the tire width direction of the second crossing belt,
The width dimension W1 along the tire width direction of the first crossing belt is set smaller than the width dimension W3 along the tire width direction of the circumferential belt,
A pneumatic tire characterized in that a width dimension W2 along the tire width direction of the second crossing belt is set larger than a width dimension W3 along the tire width direction of the circumferential belt . Width W2 along the tire width direction of the second intersecting belt pneumatic according to claim 1, characterized in that the set of 80% or more with respect to the maximum width W4 in the tire width direction cross-section of the carcass tire.

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