JPH01122702A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To surely prevent both separation of a belt end of a tire and uneven wear thereof by specifying widthwise positions of both outer ends of a reinforcing ply, and forming lateral side grooves in a pair of right and left side ribs. CONSTITUTION:A tire 1 is composed of a carcass layer 2, a tread 7, a belt layer 10 and a reinforcing layer 13. Several main grooves 8a through 8d are formed in the outer periphery of the tread 7 so that a center rib 9a and a pair of side ribs 9 are formed. In this arrangement, both widthwise outer ends 17, 18 of at least a layer of a reinforcing ply 14 forming a reinforcing layer are located widthwise inward from the widthwise outermost ends 19, 20 of the main grooves 8a, 8c. Further, several lateral grooves (not shown) are formed in each side rib 9b, being circumferentially spaced from each other and being opened to the main grooves 8a through 8d.

Description

[Detailed description of the invention] The present invention relates to a pneumatic radial tire.

Generally speaking, in pneumatic radial tires, large shear forces act between the plies at the belt ends due to diameter expansion due to internal pressure filling and ground contact deformation due to load transfer, which causes belt end separation. This may occur. In order to prevent such a situation, in the past, a cap having a strong hoop tightening effect was placed on the outside of the belt layer in the radial direction so as to cover the entire width of the belt layer.
Such a cap has a cord embedded therein that intersects the tire equatorial plane at an angle of 10 degrees or less.

−, however,
In such a pneumatic radial tire, since the cap covers the entire width of the belt layer, the belt layer has high rigidity not only at the center in the width direction but also at both ends in the width direction, making it difficult to deform. That's what happens. Generally, the crown of a pneumatic radial tire has a convex shape as a whole, so the radius of the center part is larger than the radius of the shoulder part. When ground deformation occurs due to transfer, the belt layer resists the deformation, making it difficult to absorb the radius difference between the center part and the shoulder part, and the ground contact pressure of the shoulder part decreases. A part of the shoulder becomes easily dragged, and slipping occurs between the part of the shoulder and the road surface within the ground contact surface, causing the part of the shoulder to become uneven.

There is a problem in that uneven wear such as shoulder drop occurs.

. - For this reason, the inventor of the present invention conducted extensive research and narrowed the width of the reinforcing ply (cap) to make it easier to deform both ends of the belt layer in the width direction. We devised a way to make it easier to absorb the difference in radius between the two parts. In this way, uneven wear such as uneven wear mentioned above can be prevented, but
A phenomenon (rib punching) in which only the tread (rib) in the area that overlaps with the reinforcing ply quickly wears out has been observed here and there. This is because if the circumferential length of the reinforcing ply is slightly off to the longer side, that is, if there is slack, this extra length causes the reinforcing ply and the ribs in the area overlapping with this reinforcing ply to wave in the circumferential direction. and this result,
This is because the concave portions corresponding to the valleys of the undulations become dragged when the vehicle touches the ground, causing slippage between the vehicle and the road surface and causing rapid wear of the concave portions. Therefore, the inventor of the present invention conducted further research and formed a lateral groove with both ends opening into the main groove in the tread portion at the widthwise center of the area overlapping with the reinforcing ply. This makes it possible to reduce the diameter, thereby making the radius of the outer tread portion closer to the radius of the recess, making the ground pressure uniform over a wide range, and suppressing the rib punch. Therefore, the present invention provides a carcass layer consisting of at least one carcass ply in which a cord extending in the radial direction is embedded, a tread arranged on the outside of the carcass layer in the radial direction, and a space between the carcass layer and the tread. between the carcass layer and the tread, the belt layer comprising at least two belt plies embedded with cords arranged and intersecting at an angle ranging from 10 degrees to 40 degrees with respect to the tire equatorial plane; a reinforcing layer made of a reinforcing ply of 2R or less in which a cord is embedded that intersects with the tire equatorial plane at an angle range of 10 degrees or less; The main groove of 4
In a pneumatic radial tire in which a center rib is defined at the center in the width direction of the tread and a pair of side ribs are defined on both sides of the center rib by forming one or five ribs, at least one layer of reinforcement is provided. The outer ends of the plies in the width direction are located inward in the width direction than the outermost ends in the width direction of the main groove between the center rib and the side ribs, and each side rib has a plurality of plies separated from each other in the circumferential direction and having both ends open to the main groove. lateral grooves are formed.

Although the claimed invention has a narrow width as described above, it is provided with a reinforcing ply that has a strong hoop tightening effect, so it is possible to suppress the expansion of the tire diameter due to internal pressure filling and prevent belt end separation. It became so. In addition, even if the center rib that overlaps the reinforcing ply is wavy in the circumferential direction, horizontal grooves are formed in the side rib that is not constrained by the reinforcing ply, so that the side rib follows the concave part of the center rib. Since the diameter is reduced, the ground pressure becomes uniform, and rapid wear of the recessed portion, that is, rib punching can be prevented.

L difference 1 An embodiment of this invention will be described below based on the drawings.

explain.

In Fig. 1.2.3, l is a pneumatic radial tire, and this tire 1 has a toroidal carcass layer 2, which has at least IR, and in this example one carcass ply. Consists of 3. A large number of reinforcing cords 4 made of steel or the like are embedded inside each carcass ply 3, and these cords 4 extend substantially in the radial direction, that is, in a direction substantially orthogonal to the tire equatorial plane 5. Both end portions of the carcass layer 2 are folded back around a ring-shaped bead 6. Reference numeral 7 denotes an annular tread disposed on the radially outer side of the carcass layer 2, and on the outer periphery of the tread 7 are annular main grooves 8a, 8b, 8c, which are substantially parallel to the tire equatorial plane 5.
Four or five 8d, four in this embodiment, are formed apart from each other in the width direction. As a result, the outer periphery of the tread 7 is formed by these main grooves 8a, 8b, 8C18d into a center rib 8a located at the center in the width direction, and a pair of side ribs 9b located adjacent to both sides of the center rib 9a in the width direction. and a pair of end ribs 8C located further outside in the width direction of these side ribs 9b.

In addition, when there are five main grooves 8, the central main groove 8 is located on the tire equatorial plane 5, but in this case, the center rib is the two central ribs. An annular belt layer 10 is arranged between the tread 7 and the carcass layer 2, and this belt layer 10 is composed of at least two layers, in this embodiment two layers of belt plies 11.

A large number of reinforcing cords 12 made of steel or the like are buried inside each of these belt plies 11, and the inclination directions of these cords 12 are opposite to each other with respect to the tire equatorial plane 5 for each belt ply 11. That is, they intersect with the tire equatorial plane 5 in between. The intersection angle of these cords 12 with respect to the tire equatorial plane 5 is from 10 degrees to 4 degrees.
It is within the angular range of 0 degrees. Reference numeral 13 denotes a reinforcing layer consisting of two or less reinforcing plies 14, and this reinforcing layer 13 is arranged between the tread 7 and the carcass layer 2, and in this embodiment, between the belt layer IO and the carcass layer 2. Ru. Note that this reinforcing layer 13 may be arranged between the tread 7 and the belt layer 10 or between the belt ply 11.In each auxiliary shaft ply 14, the intersection angle with respect to the tire equatorial plane 5 is determined by the cord of the belt ply 11. 12, that is, the cords 15 having an angle range of 10 degrees or less with respect to the tire equatorial plane 5 are buried in a spiral shape or in a plurality of parallel cords. Here, the reinforcing layer 13 is composed of two or less reinforcing ply 1
4, if the reinforcing ply 14 has three or more layers, the tread 7, the belt layer 10. This is because the gauge in the radial direction including the reinforcing layer 13 becomes thicker, which is harmful to the heat generating surface. Each reinforcement ply like this! The cords 15 having the angle range described above are embedded in the inner wall of the reinforcing layer 13 to provide a strong hoop tightening effect, which reduces the shearing force between the plies at the belt end when the internal pressure is filled, and the belt end separator This means that the seal is suppressed. Furthermore, since the reinforcing ply 14 in which the cord 15 having the above-mentioned angular range is embedded cannot substantially expand or contract, if the one circumference of the reinforcing ply 14 is deviated to the longer side, that is, if the reinforcing ply 14 has slack. , the surface of the tread 7 overlapping with the reinforcing ply 14 becomes wavy. When such undulation occurs, the four parts that hit the troughs of the waves are dragged and slip between them and the road surface when they touch the ground, causing rapid wear. For this reason, at least 1
Both outer widthwise ends 17 and 18 of the reinforcing ply 14 of the layer are
Main groove 8b between center rib 8a and side rib 9b,
8C, and a plurality of lateral grooves 21 are formed in each side rib 9b, spaced apart from each other in the circumferential direction, with both ends opening into the main grooves 8a, 8b, 8c, and 8d. be. As a result, each side rib 9b partitioned into blocks by the lateral grooves 21 is fl
C, it is easily deformed and reduced in diameter, and its radius approaches the radius of the recess. Therefore, the ground pressure is made uniform over a wide range, and rapid wear in the recesses is suppressed, thereby preventing rib punching. Here, both widthwise outer ends 17 and 18 of at least one layer of reinforcing ply 14 are connected to main grooves 8h and 8c between center rib 9a and side rib 9b.
The reason why it is located inside in the width direction from the outermost end 19.20 in the width direction is as follows. That is, the reinforcing ply 14 is 1
In the case of a layer, the outer ends 17 and 18 of the reinforcing ply 14 in the width direction
are located on the outer side in the width direction from the outermost ends 18.20 in the width direction of the main grooves 8b and 8C, or when the reinforcing ply 14 is two years old, the outer ends 17.18 in the width direction of both reinforcing plies 14 are located in the main groove 8b, 8c, the hoop tightening effect of the reinforcing ply 14 also acts on the side rib 9b, improving the rigidity of the side rib 8b, and reducing the diameter at the time of ground contact. In addition, since the rigidity of the side ribs 9b differs depending on the position in the width direction, only the edges of the side ribs 8b are unevenly worn (river wear).
Here, the outermost ends 19.20 in the width direction of the main grooves 8b, 8C are the outermost ends in the width direction of the main grooves 8b, 8c when the main grooves 8b, 8c are bent in a zigzag shape. Main groove 8b refers to the valley furthest from the center in the width direction of the wall.
, 8C are straight, it refers to the outer walls in the width direction of the main grooves 8b and 8c. Also, the lateral groove 21 has a size that opens into the main groove and closes when touching the ground, but this lateral groove 21 has a wide width that does not close when touching the ground. It may be the main groove of

Further, the lateral groove 21 may be linear, bent in a zigzag manner, or even curved.

Next, a test example will be explained. To start this test, Comparative Tire 1.2 and Test Tires 1, 2.3.4.5, each having a size of 10.0OR2G, were prepared. As shown in FIGS. 4(a) and 4(b), in the comparative tire 1, the outer ends 17.18 of the reinforcing ply 14 in the width direction are located inward in the width direction than the outermost ends 19.20 of the main grooves 8b, 8c in the width direction. However, this tire does not have lateral grooves formed on each side rib 9b, whereas comparative tire 2 has lateral grooves 21 formed on each side rib 9b, as shown in FIGS. 4(c) and 4(d). , the outer ends 17 and 18 of the reinforcing ply 14 in the width direction are connected to the main groove 8.
This tire is located outside in the width direction from the outermost end 18.20 in the width direction of tires b and 8c. Further, as shown in FIGS. 4(e) and 4(f), the test tire 1 is a tire with the lateral groove 21 of the size described in the above embodiment, and the test tire 2 is a tire with the size shown in FIG.
g) As shown in (h), this is a tire in which the lateral groove 21 of the tire explained in the previous example is replaced with a wide main groove instead of a sipe, and the test tire 3 is as shown in FIG. 4 (i) U). Then, a wide reinforcing ply 31 (the outer ends 32 in the width direction are the outermost ends 1θ, 2 in the width direction of the main grooves 8b, 8C) is attached to the test tire 1.
This is a tire in which a reinforcing ply (located on the outside in the width direction from 0) is added between the reinforcing ply 14 and the belt layer 10, and the test tire 4 is as shown in FIG. 4(k)(1). This is a tire in which the reinforcing ply 14 is moved from between the belt layer 10 and the carcass layer 2 to between the belt layer 10 and the tread 7 in the tire described in the previous example, and the test tire 5 is shown in FIG. m) As shown in (n), this tire has five main grooves 8, and a reinforcing ply 14 is arranged radially inside two central ribs 9a located in the center. Each of these tires is of the 2/D-4 type (the front wheel has one axle, the rear wheel has two axles, one of the rear axles is the drive shaft, and each of the rear wheels has four axles). model equipped with tires)
After installing it on the front wheel of a flat body truck, it weighs 8.0Kg.
/Crn' internal pressure and drove for 120,000 km on 80% paved expressway and 20% paved general road at 100% load rate. Next, inspect the tread of each tire after driving. did. As a result, a rib punch with a depth of 1.8H occurred in the center rib 3a of the comparison tire 1, and a rib punch with a width of 7.0cm and a depth of 1.8H occurred in the side rib 8b of the comparison tire 2. , 0■ riverware was occurring. - On the other hand, test tires 1, 3, 4, and 5 showed almost no uneven wear.
Only the test tire 2 had slight heel-and-toe wear on the side ribs 8b.As described above, uneven wear occurred to a considerable extent in each of the comparison tires that deviated from the scope of the present invention, but the present invention There was almost no uneven wear in the test tires to which this was applied, and uneven wear could be reliably prevented. Moreover, when each test tire was cut after running and the belt ends were inspected, there were almost no cracks and belt end separation was reliably prevented.

As described above, according to the present invention, both belt end separation and uneven wear can be reliably prevented.

[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 section A in FIG. 1, FIG. 3 is a developed view of the tread, and FIGS. ) is a tread development view and a meridian cross-sectional view of the tire used in the test. 2... Carcass layer 3... Carcass ply 4.
... Code 5 ... Tire equatorial plane 7 ...
Tread 8...Main groove 9a...Center rib 8b...Side rib lO...Belt layer
11... Belt braai 12... Cord
13... Reinforcement layer 14... Reinforcement ply 15...
・Code 17.18... Outer edge in the width direction 18.20... Outermost edge in the width direction 21... Yokomizo patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Figure 2 4.12. 15... Code Fig. 3 21... Lateral groove Fig. 4 Fig. 4 Fig. 4

Claims (1)

[Claims] a carcass layer comprising at least one carcass ply in which a cord extending substantially in the radial direction is embedded; a tread disposed radially outwardly of the carcass layer; A belt layer consisting of at least two belt plies in which cords intersect at an angle range of 10 degrees to 40 degrees with respect to the tire is disposed between the carcass layer and the tread; a reinforcing layer consisting of two or less reinforcing plies in which cords intersecting at an angle of 10 degrees or less are embedded, and four annular main grooves substantially parallel to the tire equatorial plane are provided on the outer periphery of the tread. In a pneumatic radial tire having one or five reinforcing plies, the pneumatic radial tire has a center rib at the center in the width direction of the tread and a pair of side ribs on both sides of the center rib. Both outer ends in the width direction of the main groove are located on the inner side in the width direction than the outermost end in the width direction of the main groove between the center rib and the side rib, and each side rib has a plurality of grooves spaced apart from each other in the circumferential direction and having both ends open to the main groove. A pneumatic radial tire characterized by forming horizontal grooves.