JPS63151504A - Pneumatic radial tyre - Google Patents

Abstract

PURPOSE:To improve durability by arranging a reinforcing ply layer in such a way that the outside end comes to be positioned outside the outer end, by a certain amount, of the widest belt ply in the width direction, at the outside of a belt layer comprised of plural layers of plies where cords cross each other with equatorial face between. CONSTITUTION:A belt layer 31 comprised of the widest belt ply 32 having cords 34, 35 which cross each other with a tyre equatorial face between and an adjacent belt ply 33 is provided at the outside, in the radial direction, of a carcass layer 22. And a reinforcing ply layer 38 comprised of reinforcing plies 40, 41 having cords 42, 43 parallel with equatorial face is provided at the outside of the belt layer 31 and its end in the width direction is positioned outside the belt layer 31. Thereupon, the distance L between the end G of the widest belt ply 32 and the cross point K of this ply extension line J and the reinforcing ply 41 is determined 0.5 times or more the radial direction distance P between the ends of the belt plies 32, 33. By this constitution, the rubber crack can be prevented at the end of the belt layer.

Description

[Detailed description of the invention] It Jomame■Dish±j The present invention relates to a pneumatic radial tire.

Husband] J and 11 Conventionally, as a pneumatic radial tire.

For example, the one shown in FIG. 3 is known.

This has a carcass M5 consisting of at least one carcass ply 2, the cords 3 reinforcing each carcass ply 2 being substantially perpendicular to the tire equatorial plane 4. A belt layer 7 consisting of at least two layers of belt plies B is arranged on the radially outer side of the crown portion of this carcass layer 5, and cords 8 reinforcing these belt plies 6 intersect with each other across the tire equatorial plane 4. . Incidentally, in recent years, tire obliqueness has been reduced in order to lower vehicle height or reduce weight.
In this way, the diameter of the shoulder portion A of the tire increases at the end of the internal pressure, and the ground contact pressure of the shoulder portion A increases. In order to prevent such a situation, conventionally, as shown in the drawing, a reinforcing ply layer 1 consisting of about two layers of reinforcing ply 9 is provided on the outside in the radial direction of the belt layer 7.
0 (generally called a layer or cap) is placed. These reinforcing plies 8 are reinforced by cords 11 which are parallel to the tire equatorial plane 4 when purchased.

However, such a pneumatic radial tire l
However, when running for a long period of time, there is a problem in that rubber cracks occur between the outer end B in the width direction of the widest belt ply 8a and the reinforcing ply layer 10, eventually leading to separation.

Therefore, as a result of intensive research by the present inventor, all reinforcing plies 9
If the outer end C in the width direction is located on the outer side in the width direction than the outer end B in the width direction of the widest belt ply 6a, the reinforcing ply 8 will remove the rubber between the reinforcing ply 9 and the outer end B in the width direction. It has been found that by strongly restraining the rubber, as a result, a large shear strain is generated in the rubber at this portion due to circumferential displacement of the outer end B in the width direction during running, and this causes the rubber cracks as described above. This invention was made based on the above-mentioned knowledge, and consists of at least one carcass ply, and each carcass ply has a cord extending between a carcass layer substantially perpendicular to the tire equatorial plane and a cord extending radially outward of the carcass layer. at least a widest belt ply and an adjacent belt ply adjacent to the widest belt ply, and the cords of the widest belt ply and the adjacent belt ply intersect with belt layers across the tire equatorial plane. a pneumatic radial tire comprising: a reinforcing ply layer disposed radially outwardly of the belt layer and comprising at least IM reinforcing ply layers, the cords of each reinforcing ply being substantially parallel to the tire equatorial plane; The outer end in the width direction of the reinforcing ply layer is located on the outer side in the width direction than the outer end in the width direction of the widest belt ply, and the width direction distance from the outer end in the width direction of the widest belt ply to the reinforcing ply layer is By making it at least 0.5 times the radial distance from the outer edge of the ply in the width direction to the widest belt braai,
This solves the above problems.

1. When the vehicle is running, the outer edge of each belt ply in the width direction is displaced in the circumferential direction due to the deformation of the tire due to contact with the ground.
The rubber around these outer ends is also affected by this displacement and deforms. Here, the shear strain based on the deformation has a maximum value between the widthwise outer end of the widest belt brace and the reinforcing belt in the past, but in this invention, the shear strain from the widthwise outer end of the widest belt brace By setting the distance in the width direction to the reinforcing ply layer to be at least 0.5 times the radial distance from the outer edge of the adjacent belt ply in the width direction to the widest belt ply, the width of the widest belt ply is increased, and the inside of the rubber between this layer is This reduces the value of shear strain that occurs.

Actual example Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1.2, 21 is a pneumatic radial tire used for example in passenger cars, light trucks, etc. This tire 21 has a toroidal carcass layer 22, and this carcass M22 has at least one layer. In the example, it consists of one layer of carcass ply 23. A large number of reinforcing cords 24 made of textile or the like are buried inside each carcass ply 23, and these cords 24 are perpendicular to the tire equatorial plane 25 when actually purchased. Both end portions of the carcass layer 22 are folded back around the ring-shaped bead 2B. Reference numeral 31 denotes an annular belt layer disposed on the radially outer side of the crown portion 27 of the carcass M22. It has at least two belt plies. The adjacent belt ply 33 is located outside the widest belt ply 32 in the radial direction. Inside these widest and adjacent belt plies 32 and 33, there are numerous reinforcing cords 34 and 3 made of steel or the like.
5 are buried respectively, and the inclination directions of these cords 34 and 35 are opposite to each other with respect to the tire equatorial plane 25, that is, they intersect with the tire equatorial plane 25 in between. The intersection angles of these cords 34 and 35 with respect to the tire equatorial plane 25 are within the range of 10 degrees to 30 degrees. In addition,
When the belt layer 31 is composed of three or more belt plies, the widest width, adjacent belt ply 32.3
Reinforcing cords that are inclined in the same direction or in the opposite direction to the cords of the widest belt ply 32 are also buried in the belt plies other than 3. Reference numeral 38 denotes a reinforcing ply layer disposed on the radially outer side of the belt layer 31 in order to suppress diameter growth and ground pressure increase in the shoulder portion 38 of the tire 21. In this embodiment, this reinforcing ply layer 38 is a single layer. It surrounds the outer end of the belt layer 31 in the width direction. The reinforcing ply calendar 38 consists of at least one layer of reinforcing ply, in this embodiment two layers of reinforcing ply 40, 41, each reinforcing ply 40, 41 has a plurality of reinforcing plies substantially parallel to the tire equatorial plane 25 inside. Reinforcement cords 42 and 43 are buried respectively. The outer ends E and F in the width direction of these reinforcing plies 40.41 are the outer ends G in the width direction of the widest belt ply 32.
It is located further outward in the width direction. The sum of the elastic modulus per unit width in the cord extending direction of the reinforcement plies 40° 41 is 0.015 times the sum of the elastic modulus per unit width in the cord extending direction of the belt ply 32.33. It is preferable to be within a range of up to 0.2 GO times.

The reason is that if the value is less than 0.015 times, the effect of suppressing the diameter growth of the cylinder part 39 during internal pressure filling becomes too small, and if it exceeds 0.200 times, the tire This is because uneven wear is likely to occur on 21. Codes 42.43 within the range like this
Examples of the material include nylon. 4B is a cushion rubber interposed between the outer end in the width direction of the widest belt ply 32 and the outer end in one direction of the adjacent belt ply 33; This alleviates the inter-ply shear strain that occurs between the ply 33 and prevents cracks from occurring between them. In this embodiment, these cushion rubber 4
The width of B is made wider than the conventional one, and its outer end in the width direction extends between the outer end G in the width direction of the widest belt ply 32 and the reinforcing ply M38. here.

Let K be the intersection of the extension line J of the widest belt ply 32 and the reinforcing ply 40 of the innermost layer, and let N be the intersection of the widest belt ply 32 and the normal M passing through the outer end H in the width direction of the adjacent belt ply 33. Then, the width direction distance L between the width direction outer end G of the widest belt ply 32 and the intersection point, that is, the width direction distance from the width direction outer end G to the reinforcing ply layer 38 is equal to the width of the adjacent belt ply 33. The radial distance P between the outer end H in the direction and the intersection point N, that is, the radial distance from the outer MH in the width direction to the widest heirt ply 32 must be at least 0.5 times the above value. If it is less than 0.5 times, as is clear from the test results described below, large shear strain will occur in the rubber between the widest belt ply 32 and the reinforcing ply layer 38, and rubber cracks will rapidly progress. be. - the radial distance P is the widest belt ply 3;
It is preferable that the range is from 0.5% to 2.7% of the belt convergence Q of No. 2. The reason is that if the value is less than 0.5%, the outer end H in the width direction of the adjacent belt ply 33 This is because shear strain concentrates and separation tends to occur.On the other hand, if it exceeds 2.7%, the thickness of the rubber in the tread portion 48 (tread gauge) becomes too thin to be of practical use.

Next, the operation of one embodiment of the present invention will be explained.

When the tire 21 as described above is run, the tire 2
The three ground contact areas of No. 1 are significantly deformed. At this time, the cords 34.35 buried in the belt plies 32.33 are displaced in the circumferential direction to a greater extent as they approach the widthwise outer ends G, H based on the above deformation. The largest displacement occurs at the outer end G in the width direction. For this reason,
The rubber around this outer end G in the width direction tends to be significantly deformed under the influence of this displacement. However, since a highly rigid reinforcing ply fi38 that does not displace in the circumferential direction is arranged around the outer end G in the width direction, a large shear is applied to the rubber between the outer end G in the width direction and the reinforcing ply M38. do. Therefore, in the present invention, the widthwise distance from the widthwise outer end G of the widest belt ply 32 to the reinforcing ply layer 38 is the widthwise distance from the widthwise outer end H of the adjacent belt ply 33 to the widest belt ply 32. Radial pressure 1IlIP
By making it 0.5 times or more, the space between the outer end G in the width direction and the reinforcing ply layer 38 is widened, and the shear strain generated in the rubber between them is reduced.

Next, a test example will be explained. For this test, test tires 1, 2.3, and 4 to which the present invention was applied, and conventional comparative tires 1 and 2 were prepared.

Here, the size of all these tires is 235150R1
3,5, and the widest belt ply 32 has a cord angle (intersection angle with respect to the tire equatorial plane 25) of 20
The tensile modulus is 5. OX 10104 (/C layer), the adjacent belt ply 33 has a cord angle of 20 degrees upward to the left and a tensile modulus of elasticity (5, OX1 tolerance (Kg/Cm), 6
Pry, reinforcement.

A40.41 all have a cord angle of 0 degrees and a tensile modulus of 1.
．． After filling such a tire with an internal pressure of 4.5 (Kg/C) which was 3X 10 (Kg/C),
A load of 850 kg was applied to the cord, and the cord was traveled for 40,000 km at a speed of 80 km, and the length of the crack at the end of each belt ply 32 and 33 at this time was measured along the longitudinal direction of the cord. The results are shown in the attached table using an index, and in the attached table, the index 100 was actually 10 mm. As is clear from this test result, in all the test tires, that is, tires with L/P of 0.5 or more, the crack length at the belt end of the widest belt ply was smaller than in comparison tires 1 and 2. It has become.

11 Rikuo J As explained above, according to the present invention, it is possible to reliably suppress the occurrence of cracks in the rubber around the outer end in the width direction of the widest belt ply.

[Brief explanation of the drawing]

FIG. 1 is a meridian sectional view of a tire showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, and FIG. 3 is a meridian sectional view showing a conventional pneumatic radial tire. 21... Pneumatic tire 22... Carcass layer 23
... Carcass ply 24 ... Cord 25 ... Tire equatorial plane 31 ... Bell He32 ... Widest belt ply 33 ... Adjacent belt ply 34.35 ... Code 3B ... Reinforcement ply Layer 40.41... Reinforcement ply 42.43... Code patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Figure 1 21... Pneumatic tire 22... Carcass layer
23... Carcass ply 24... Cord
25...Tire equatorial plane 31...Belt layer 32
... Widest belt ply 33 ... Adjacent belt ply 34.35 ... Cord 38 ... Reinforcement ply layer 40.41 ... Reinforcement ply 42.43.
...Code Figure 2

Claims (1)

[Claims] The cords of each carcass ply are comprised of at least one layer of carcass ply, the cords of each carcass ply being arranged in a carcass layer substantially perpendicular to the tire equatorial plane, a widest belt ply located radially outwardly of the carcass layer, and a widest belt ply having the widest width; The belt ply has at least an adjacent belt ply adjacent to the belt ply, and the cords of the widest and adjacent belt plies intersect with each other across the tire equatorial plane, and at least one belt ply arranged radially outward of the belt layer. A pneumatic radial tire comprising: a reinforcing ply layer in which the cord of each reinforcing ply is substantially parallel to the tire equatorial plane; The distance in the width direction from the outer end in the width direction of the widest belt ply to the reinforcing ply layer is the same as the distance in the width direction from the outer end in the width direction of the adjacent belt ply to the widest belt ply. A pneumatic radial tire characterized in that the distance in the radial direction is 0.5 times or more.