JP2019111859A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can suppress a difference in grounding length from occurring between a first side and a second side in a tire width direction during forward travelling.SOLUTION: In the pneumatic tire, a rubber surface layer part comprises a first rubber part formed of first rubber, and a second rubber part formed of second rubber with a rubber hardness higher than a rubber hardness of the first rubber. The first rubber part is arranged on a first side in a tire width direction, and the second rubber part is arranged on a second side in the tire width direction. An interface between the first rubber part and the second rubber part is arranged between a pair of main grooves arranged on an outermost side in the tire width direction. A belt part comprises at least one belt layer, and at least one center in the tire width direction of the belt layer is positioned closer to the first side in the tir width direction than a tire equatorial plane.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, a pneumatic tire is provided with a rubber surface layer having an outer surface in the tire radial direction, and the first and second sides of the rubber surface layer in the tire width direction are formed of rubber having different rubber hardness. (E.g., Patent Document 1). In such a pneumatic tire, since a difference in the contact length is generated between the first side and the second side in the tire width direction when going straight, for example, the conicity generated when going straight (force acting in the tire width direction) ) Will be larger.

JP 2012-76593 A

  Then, a subject is providing the pneumatic tire which can suppress that the difference of contact-contact length arises between the 1st side of a tire width direction, and a 2nd side at the time of going straight.

  The pneumatic tire is a pneumatic tire provided with a plurality of main grooves extending in the circumferential direction of the tire, and is disposed on the rubber surface portion having an outer surface in the radial direction of the tire and inside the tire surface in the tire radial direction A belt portion, and the rubber surface layer portion is formed of a first rubber portion formed of a first rubber, and a second rubber portion having a rubber hardness greater than that of the first rubber. A rubber portion, the first rubber portion is disposed on a first side in the tire width direction, and the second rubber portion is disposed on a second side in the tire width direction, and the first rubber portion and the first rubber portion are disposed. The interface with the second rubber portion is disposed between a pair of main grooves disposed outermost in the tire width direction, the belt portion includes at least one belt layer, and at least one of the belt layers, The center in the tire width direction is the tire rather than the tire equatorial plane Located in a first side direction.

  Further, in the pneumatic tire, the second rubber portion may be disposed outside when the vehicle is mounted.

  Further, in the pneumatic tire, all the belt layers may be configured to overlap with the ground contact end on the second side in the tire width direction in the tire radial direction.

  In addition, the pneumatic tire includes a plurality of land portions defined by the plurality of main grooves and the ground contact end, and the void ratio of the land portion formed of the first rubber portion is formed of the second rubber portion. The configuration may be smaller than the void ratio of the land portion to be cut.

  Further, in the pneumatic tire, the belt portion includes a first belt layer and a second belt layer disposed on the outer side in the tire radial direction than the first belt layer, and the second belt layer The center in the tire width direction may be positioned on the first side in the tire width direction with respect to the center in the tire width direction of the first belt layer.

  In addition, the pneumatic tire may include a center land portion including the tire equatorial plane by being divided by the plurality of main grooves, and the interface may be located at the center land portion.

FIG. 1 is a cross-sectional view of an essential part of a tire meridional surface of a pneumatic tire according to an embodiment. FIG. 2 is a development view of a tread surface of the pneumatic tire according to the embodiment. FIG. 3 is an enlarged view of a III region of FIG. FIG. 4 is an enlarged view of a III region of FIG. 1 and shows the position of the belt portion. FIG. 5 is an enlarged view of a region V of FIG. 1 and showing the position of the belt portion. FIG. 6 is an enlarged view of a VI area of FIG. 1 and showing the position of the belt portion. FIG. 7 is a view showing a contact shape of a pneumatic tire according to a comparative example. FIG. 8 is a view showing a contact shape of the pneumatic tire according to FIGS. 1 to 6. FIG. 9 is an enlarged sectional view of an essential part of a tire meridional surface of a pneumatic tire according to another embodiment, showing a position of a belt portion. FIG. 10 is an enlarged sectional view of an essential part of a tire meridional surface of a pneumatic tire according to still another embodiment, showing a position of a belt portion. FIG. 11 is an evaluation chart of an example of a pneumatic tire. FIG. 12 is an evaluation chart of an example of a pneumatic tire.

  Hereinafter, one embodiment of a pneumatic tire will be described with reference to FIGS. 1 to 8. In each of the drawings (the same applies to FIG. 9 and the subsequent figures), the dimensional ratio of the drawings and the actual dimensional ratio do not always match, and the dimensional ratio between the respective drawings does not necessarily match.

  In each figure, the first direction D1 is the tire width direction D1 parallel to the tire rotation axis which is the rotation center of the pneumatic tire (hereinafter, also simply referred to as "tire") 1, and the second direction D2 is The tire radial direction D2 is a diameter direction of the tire 1, and the third direction D3 is the tire circumferential direction D3 around the tire rotation axis. In the tire width direction D1, the first side D11 is also referred to as a first width direction side D11, and the second side D12 is also referred to as a second width direction side D12.

  The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and located at the center of the tire 1 in the tire width direction D1. The tire meridional plane is a plane including the tire rotation axis and the tire equatorial plane It is a plane orthogonal to the plane S1. The tire equator line is a line at which the outer surface of the tire 1 in the tire radial direction D2 (a tread surface 2a described later) intersects with the tire equator surface S1.

  As shown in FIG. 1, the tire 1 according to the present embodiment includes a pair of bead portions 11 having beads, sidewall portions 12 extending from the bead portions 11 to the outside in the tire radial direction D2, and a pair of sidewall portions The tread portion 2 is connected to the outer end portions of the twelve tire radial directions D2, and the outer surface of the tire radial direction D2 is in contact with the road surface. In the present embodiment, the tire 1 is a pneumatic tire 1 having air introduced therein, and is mounted on a rim 20.

  In addition, the tire 1 is provided with a carcass layer 13 bridged between a pair of beads, an inner liner layer 14 which is disposed inside the carcass layer 13 and is excellent in the function of blocking gas permeation in order to maintain air pressure. Is equipped. The carcass layer 13 and the inner liner layer 14 are disposed along the tire inner circumference across the bead portion 11, the sidewall portion 12, and the tread portion 2.

  The tread portion 2 includes a tread rubber 3 having a tread surface 2 a that is in contact with a road surface, and a belt portion 4 disposed between the tread rubber 3 and the carcass layer 13. The tread portion 2 further includes a belt reinforcing portion 5 disposed between the tread rubber 3 and the belt portion 4 in order to reinforce the belt portion 4.

  The tread surface 2a has a contact surface that actually contacts the road surface, and among the contact surfaces, the outer ends in the tire width direction D1 are referred to as contact ends 2b and 2c. The tread surface 2a has the tire 1 mounted on a regular rim 20 and is filled with a regular internal pressure. The tire 1 is placed vertically on a flat road surface, and the tread surface 2a is in contact with the road surface when a regular load is applied. Point to Further, of the ground ends 2b and 2c, the ground end 2b on the first widthwise side D11 is referred to as a first ground end 2b, and the ground end 2c on the second widthwise side D12 is referred to as a second ground end 2c.

  In the standard system including the standard on which the tire 1 is based, the regular rim 20 is the rim 20 which is defined for each tire 1 in the standard, for example, if it is JATMA, it is a standard rim, if it is TRA, "Design Rim", ETRTO If it is "Measuring Rim".

  The normal internal pressure is the air pressure specified in each tire 1 in the standard system including the standard on which the tire 1 is based, the maximum air pressure in the case of JATMA, the table in the case of TRA, "TIRE LOAD LIMITS AT VARIOUS COLD The maximum value described in “INFLATION PRESSURES” is “INFLATION PRESSURE” in the case of ETRTO, but is 180 kPa when the tire 1 is for a passenger car.

  The normal load is a load defined in each tire 1 in the standard system including the standard on which the tire 1 is based, the maximum load capacity in the case of JATMA, and the maximum in the above table in the case of TRA. If the value is ETRTO, it is "LOAD CAPACITY", but if the tire 1 is for a passenger car, it is 85% of the corresponding load of internal pressure 180 kPa.

  The belt portion 4 includes at least one (two in the present embodiment) belt layers 41 and 42. Specifically, the belt portion 4 includes a first belt layer 41 and a second belt layer 42 disposed outside the first belt layer 41 in the tire radial direction D2. Each of the belt layers 41 and 42 includes a plurality of belt cords arranged in parallel, and a topping rubber that covers the belt cords. The number of layers of the belt layers 41 and 42 is not particularly limited.

  The belt cords of the belt layers 41 and 42 are parallel to the tire width direction D1 so as to intersect at a predetermined inclination angle (for example, 5 ° or more, preferably 15 ° to 35 °) with respect to the tire circumferential direction D3. It is done. The belt cords of the first and second belt layers 41 and 42 are inclined in opposite directions with respect to the tire circumferential direction D3 and arranged to intersect with each other. Although the material of the belt cord is not particularly limited, for example, organic fibers such as polyester, rayon, nylon, or aramid, and metals such as steel are suitably used.

  The belt reinforcing portion 5 includes a cap reinforcing layer 51 disposed to cover the belt layers 41 and 42 in the tire width direction D1, and end portions 41a, 41b and 42a of the belt layers 41 and 42 in the tire width direction D1. Edge reinforcing layers 52, 53 disposed to cover 42b. And belt reinforcement part 5 is provided with a reinforcement cord and topping rubber which covers a reinforcement cord. Although the material of the reinforcing cord is not particularly limited, for example, organic fibers such as polyester, rayon, nylon, or aramid are suitably used.

  The belt reinforcing portion 5 is formed by spirally winding at least one reinforcing cord covered with topping rubber along the tire circumferential direction D3. Thereby, the reinforcing cords of the respective reinforcing layers 51 to 53 extend along the tire circumferential direction D3 (for example, to intersect at an inclination angle of less than 5 °, preferably 3 ° or less with respect to the tire circumferential direction D3) Or, it is parallel to the tire width direction D1 so as to be parallel to the tire circumferential direction D3.

  As shown in FIGS. 1 and 2, the tread rubber 3 includes a plurality of main grooves 3 a and 3 b extending in the tire circumferential direction D3. The main grooves 3a, 3b extend continuously in the tire circumferential direction D3. In the present embodiment, the main grooves 3a and 3b extend in a straight shape along the tire circumferential direction D3. However, the present invention is not limited to such a configuration. For example, refraction is repeated to extend in a zigzag shape , Or, for example, may be configured to extend in a wave shape by repeating bending.

  The main grooves 3a, 3b are provided with a portion where the grooves are shallow, so-called tread wear indicator (not shown), for example, so that the degree of wear can be known by exposing as the wear. Further, for example, the main grooves 3a and 3b have a groove width of 3% or more of the distance between the ground contact ends 2b and 2c (the dimension in the tire width direction D1). Also, for example, the main grooves 3a and 3b have a groove width of 5 mm or more.

  In the plurality of main grooves 3a, 3b, the pair of main grooves 3a, 3a arranged on the outermost side in the tire width direction D1 is called shoulder main groove 3a, and is arranged between the pair of shoulder main grooves 3a, 3a The main groove 3b to be formed is called a center main groove 3b. In the present embodiment, although the number of the center main grooves 3b is two, it is not limited to such a configuration, and may be one or three or more, for example.

  The tread rubber 3 includes a plurality of land portions 3c to 3e divided by the main grooves 3a and 3b and the ground contact ends 2b and 2c. In the plurality of land portions 3c to 3e, the land portions 3c partitioned by the shoulder main groove 3a and the ground ends 2b and 2c are called shoulder land portions 3c, and are partitioned by adjacent main grooves 3a and 3b, Land portions 3d and 3e disposed between the pair of shoulder land portions 3c and 3c are referred to as middle land portions 3d and 3e.

  Of the middle land portions 3d and 3e, the land portion 3d divided by the shoulder main groove 3a and the center main groove 3b is referred to as a median land portion 3d, and the land divided by the center main grooves 3b and 3b. The part 3e is called the center land part 3e. In the present embodiment, the center main grooves 3b, 3b are disposed so as to sandwich the tire equatorial plane S1, and thereby the center land portion 3e is disposed so as to include the tire equatorial plane S1.

  The land portions 3c to 3e are provided with a plurality of land grooves 3f and 3g. The plurality of land grooves 3f and 3g extend so as to intersect with the tire circumferential direction D3. Of the land grooves 3f and 3g extending to intersect the tire circumferential direction D3, the land groove 3f having a groove width of 1.6 mm or more is referred to as a width groove 3f, and the groove width is less than 1.6 mm. Some land grooves 3g are called sipes 3g. Land portions 3c to 3e may be provided with land grooves having a groove width smaller than the groove width of main grooves 3a and 3b and extending continuously or intermittently along tire circumferential direction D3. The grooves are called circumferential grooves.

  In addition, the tire 1 has a structure that is asymmetric with respect to the tire equatorial plane S1. In the present embodiment, the tire 1 is a tire whose mounting direction to a vehicle is specified, and when mounted on the rim 20, it is a tire whose left or right of the tire 1 is specified to face the vehicle. The tread pattern formed on the tread surface 2 a of the tread portion 2 has a shape that is asymmetric with respect to the tire equatorial plane S1.

  The direction of attachment to the vehicle is displayed on the sidewall 12. Specifically, the sidewall portion 12 is provided with sidewall rubber 12a disposed on the outer side in the tire width direction D1 of the carcass layer 13 so as to constitute the outer surface of the tire, and the surface of the sidewall rubber 12a is displayed Have a department.

  For example, when the vehicle is mounted, one sidewall portion 12 disposed on the inner side (the left side in each drawing, hereinafter also referred to as "the inner side of the vehicle") is an indication to be the inner side of the vehicle (for example, "INSIDE" ) Is attached. Also, for example, when the vehicle is mounted, the other sidewall portion 12 disposed on the outer side (right side in each drawing, hereinafter also referred to as “vehicle outer side”) is an indication that it is the vehicle outer side (for example, “OUTSIDE Etc.) is attached. In the present embodiment, the first widthwise side D11 is an inner side of the vehicle, and the second widthwise side D12 is an outer side of the vehicle.

  As shown in FIG. 3, the tread rubber 3 has a rubber surface layer portion 6 having a tread surface 2 a which is an outer surface in the tire radial direction D 2 and a rubber inner layer disposed on the inner side of the rubber surface portion 6 in the tire radial direction D 2. And 7 are provided. In addition, not only the structure that it is one layer, but the structure of being two or more layers may be sufficient as the rubber | gum inner-layer part 7. FIG. Further, in the rubber inner layer portion 7, the rubber inner layer portion 7 disposed at the innermost in the tire radial direction D2 is referred to as a base rubber, and the rubber surface layer portion 6 and the other rubber inner layer portions 7 are referred to as a cap rubber.

  The rubber surface layer portion 6 includes a first rubber portion 6a formed of a first rubber, and a second rubber portion 6b formed of a second rubber having a rubber hardness greater than that of the first rubber. . The rubber hardness is a hardness measured at 23 ° C. based on “JIS K6253-1-2012 3.2 durometer hardness”.

  Although the rubber hardness of each rubber is not particularly limited, for example, the rubber hardness of the first rubber may be 66 to 70, and the rubber hardness of the second rubber may be 70 to 74, for example. Also, for example, the rubber hardness difference between the first rubber and the second rubber is not particularly limited, but may be 2 to 6, for example.

  The rubber surface layer portion 6 includes an interface 6c between the first rubber portion 6a and the second rubber portion 6b. The interface 6c is disposed between the pair of shoulder main grooves 3a and 3a. As a result, distortion occurs at the interface 6c disposed between the pair of shoulder main grooves 3a, 3a at the time of braking, so the distortion becomes a resistance to the road surface. Therefore, since the braking distance can be reduced, the braking performance can be improved.

  Further, in the present embodiment, the interface 6c is located not on the main grooves 3a and 3b but on the land portion 3e so as to appear on the tread surface 2a. Thereby, distortion generated at the interface 6c becomes a direct resistance to the road surface.

  Moreover, in the present embodiment, the interface 6c is located on the center land portion 3e, specifically, on the tire equatorial plane S1. Thereby, the interface 6c is closest to the tire equatorial plane S1 (specifically, includes the tire equatorial plane S1) while the interface land 6c is closest to the tire equatorial plane S1 as the contact pressure at the time of braking increases. It will be located at 3e. As a result, the distortion generated at the interface 6c becomes an effective resistance to the road surface, so that the braking distance can be effectively reduced.

  The interface 6c may be, for example, positioned in the main grooves 3a and 3b and may not appear in the tread surface 2a. The interface 6c may be located at the middle land portions 3d and 3e, but may be located at the media land portion 3d.

  The interface 6c may be located at the center land portion 3e, but may be located away from the tire equatorial plane S1. For example, the distance between the interface 6c and the tire equatorial plane S1 is preferably 10% or less of the distance between the ground contact ends 2b and 2c (the dimension in the tire width direction D1), and is 5% or less Is more preferable, and 3% or less is very preferable.

  Moreover, in the present embodiment, the first rubber portion 6a is disposed on the first widthwise side D11, and the second rubber portion 6b is disposed on the second widthwise side D12. That is, the first rubber portion 6a is disposed inside the vehicle, and the second rubber portion 6b is disposed outside the vehicle. As a result, the second rubber portion 6b having a relatively large rubber hardness is disposed on the vehicle outer side where the ground contact area increases when turning. Therefore, since the rigidity on the outside of the vehicle can be increased, steering stability performance at the time of turning can be improved.

  Returning to FIG. 2, in the present embodiment, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a is greater than the void ratio of the land portions 3c to 3e formed of the second rubber portion 6b. It is getting smaller. Thus, the void ratios of land portions 3c to 3e formed of the first rubber portion 6a having a relatively small rubber hardness are the land portions 3c to 3e formed of the second rubber portion 6b having a relatively large rubber hardness. It is smaller than the void ratio of Therefore, it can suppress that the rigid difference of the land parts 3c-3e of the 1st width direction side D11 and the land parts 3c-3e of the 2nd width direction side D12 becomes large.

  Land portions 3c to 3e configured by the first rubber portion 6a are the first width direction D11 of the shoulder land 3c and the median land 3d on the first width direction D11, and the center land 3e. Area of Therefore, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a is equal to the area of the land portions 3c to 3e between the first ground end 2b and the interface 6c (does not include the main grooves 3a and 3b , The ratio of the sum of the areas of the land grooves 3f and 3g to the sum of the land grooves 3f and 3g). 0

  Further, land portions 3c to 3e configured by the second rubber portion 6b are the second width direction side D12 of the shoulder land portion 3c and the median land portion 3d on the second width direction D12 and the center land portion 3e. Area of Therefore, the void ratio of the land portions 3c to 3e formed of the second rubber portion 6b is the area of the land portions 3c to 3e between the second ground end 2c and the interface 6c (does not include the main grooves 3a and 3b) , The ratio of the sum of the areas of the land grooves 3f and 3g to the sum of the land grooves 3f and 3g).

  The pitch of the width grooves 3f (the interval in the tire circumferential direction D3) in the median land portion 3d on the first width direction D11 is the pitch of the width grooves 3f in the median land portion 3d on the second width direction D12. It's getting bigger than that. The pitch of the width grooves 3f (except for the sipe 3g) in the shoulder land portion 3c of the first width direction D11 is larger than the pitch of the width groove 3f in the shoulder land 3c of the second width direction D12. It has become.

  Here, the configuration of the belt unit 4 will be described with reference to FIGS. 4 to 6. 4 to 6 (the same applies to FIGS. 9 and 10), the belt portion 4 (belt layers 41 and 42) is hatched and illustrated.

  As shown in FIGS. 4 to 6, the dimension of the first belt layer 41 in the tire width direction D1 is larger than the dimension of the second belt layer 42 in the tire width direction D1. The end portions 41 a and 41 b of the first belt layer 41 are disposed outside the end portions 42 a and 42 b of the second belt layer 42 in the tire width direction D 1.

  As shown in FIG. 4, the centers 41c and 42c of the first and second belt layers 41 and 42 in the tire width direction D1 are located on the first width direction D11 with respect to the tire equatorial plane S1. The center 41c of the first belt layer 41 and the center 42c of the second belt layer 42 are at the same position in the tire width direction D1. That is, the distance W1 between the center 41c of the first belt layer 41 and the tire equatorial plane S1 is the same as the distance W2 between the center 42c of the second belt layer 42 and the tire equatorial plane S1.

  Thereby, with respect to the tire equatorial plane S1, the area of the belt layers 41 and 42 disposed on the first width direction side D11 is more than the area of the belt layers 41 and 42 disposed on the second width direction side D12, growing. Although the distances W1 and W2 between the centers 41c and 42c of the belt layers 41 and 42 and the tire equatorial plane S1 are not particularly limited, for example, 3% or less of the dimension of the first belt layer 41 in the tire width direction D1. It is preferable to do.

  As shown in FIG. 5, the first and second belt layers 41 and 42 overlap the first ground contact end 2 b in the tire radial direction D2. Specifically, the first ends 41a and 42a of the first and second belt layers 41 and 42 are respectively outside the tire width direction D1 than the first ground end 2b, specifically, the first width direction. Located on the side D11.

  The first end 41a of the first belt layer 41 and the outer surface of the tire 1 are separated by a predetermined distance (hereinafter, also referred to as "rubber thickness distance") W3. Further, the first end 41a of the first belt layer 41 and the first end 42a of the second belt layer 42 are separated by a predetermined distance (hereinafter also referred to as "belt end distance") W4 in the tire width direction D1. is seperated.

  Further, although the first and second belt layers 41 and 42 are positioned shifted to the first width direction side D11, as shown in FIG. 6, the first and second belt layers 41 and 42 are , And the second ground contact end 2c in the tire radial direction D2. Specifically, the second ends 41b and 42b of the first and second belt layers 41 and 42 are respectively located outside the tire width direction D1 than the second ground end 2c, specifically, the second width direction. Located on the side D12.

  The second end 41 b of the first belt layer 41 and the outer surface of the tire 1 are separated by a predetermined distance (rubber thickness distance) W5. Further, the second end 41b of the first belt layer 41 and the second end 42b of the second belt layer 42 are separated by a predetermined distance (distance between belt ends) W6 in the tire width direction D1.

  The rubber thickness distances W3 and W5 are not particularly limited. However, when the rubber thickness distances W3 and W5 are small, the outer surface of the tire 1 is likely to be cracked due to being used. Therefore, it is preferable that rubber | gum thickness distance W3, W5 is 8 mm or more, for example.

  Further, the belt end-to-end distances W4 and W6 are not particularly limited. However, when the belt end-to-end distances W4 and W6 are small, air is likely to be mixed between the end portions 41a and 42a (41b and 42b) of the belt layers 41 and 42 at the time of manufacture. Therefore, it is preferable that the belt end-to-end distances W4 and W6 be, for example, 5 mm or more.

  The configuration of the pneumatic tire 1 according to the present embodiment is as described above, and next, the operation of the pneumatic tire 1 according to the present embodiment will be described.

  For example, FIG. 7 shows a contact shape of a tire according to a comparative example (in FIG. 7 (same as in FIG. 8, land grooves 3 f and 3 g are not shown)). The tire according to the comparative example is a tire in which the centers 41c and 42c of the belt layers 41 and 42 are positioned on the tire equatorial plane S1 as compared with the tire 1 according to the present embodiment. .

  And in the tire concerning a comparative example, since the 1st rubber part 6a whose rubber hardness is relatively small on the 1st width direction side D11 is arranged, the grounding length on the 1st width direction D11 (grounding shape The length in the tire circumferential direction D3 is longer than the contact length on the second widthwise side D12. Thereby, since the difference between the ground contact length on the first width direction D11 and the ground contact length on the second width direction D12 is large, for example, the conicity (force acting toward the first width direction D11) generated when going straight is growing.

  On the other hand, in the tire 1 according to the present embodiment, the centers 41c and 42c of the belt layers 41 and 42 are located on the first widthwise side D11 relative to the tire equatorial plane S1 (see FIG. 4) . Thus, in the belt layers 41 and 42, the region disposed on the first width direction side D11 with respect to the tire equatorial plane S1 is the second width direction side D12 with respect to the tire equatorial plane S1 of the belt layers 41 and 42. It will be larger than the area placed on

  Therefore, since the belt layers 41 and 42 reinforce the first width direction D11 more strongly than the second width direction D12, the rigidity between the first width direction D11 and the second width direction D12 can be obtained. It is possible to suppress the occurrence of a difference. As a result, in the tire 1 according to the present embodiment, as shown in FIG. 8, it is possible to suppress the difference between the contact length on the first width direction D11 and the contact length on the second width direction D12. is made of. Therefore, it can suppress that the conicity which generate | occur | produces at the time of straight advance becomes large.

  In addition, there is a concern that the rigidity of the second widthwise side D12 may be reduced by the first and second belt layers 41 and 42 being shifted to the first widthwise side D11. On the other hand, the first and second belt layers 41 and 42 overlap the second ground contact end 2c in the tire radial direction D2 (see FIG. 6).

  As a result, it is possible to suppress the decrease in rigidity of the region outside the vehicle while suppressing the occurrence of the difference in the ground contact length between the first widthwise side D11 and the second widthwise side D12. Therefore, it is possible to suppress the decrease in the steering stability during turning while suppressing the increase in the conicity generated when going straight.

  The center 41c of the first belt layer 41 and the center 42c of the second belt layer 42 are at the same position in the tire width direction D1. As a result, it is possible not only to suppress the increase in the conicity generated when going straight but also to suppress the separation (separation) of the first belt layer 41 and the second belt layer 42 from the surroundings.

  From the above, the pneumatic tire 1 according to the present embodiment is the pneumatic tire 1 including the plurality of main grooves 3a and 3b extending in the tire circumferential direction D3, and the rubber surface layer portion 6 having the outer surface in the tire radial direction D2. And a belt portion 4 disposed on the inner side in the tire radial direction D2 than the rubber surface portion 6, and the rubber surface portion 6 is formed of a first rubber portion 6a formed of a first rubber, and the first rubber portion 6a. And a second rubber portion 6b formed of a second rubber having a rubber hardness greater than that of 1 rubber, and the first rubber portion 6a is disposed on the first side D11 in the tire width direction D1. The second rubber portion 6b is disposed on the second side D12 in the tire width direction D1, and the interface 6c between the first rubber portion 6a and the second rubber portion 6b is disposed on the outermost side in the tire width direction D1. Between the pair of main grooves 3a, 3a, 4 includes at least one belt layer 41, 42, and the center 41c, 42c of at least one of the belt layers 41, 42 in the tire width direction D1 is the first in the tire width direction D1 than the tire equatorial plane S1. It is located at 1 side D11.

  According to such a configuration, distortion occurs at the interface 6c between the first rubber portion 6a and the second rubber portion 6b at the time of braking. And since the interface 6c is disposed between the pair of main grooves 3a, 3a disposed at the outermost side in the tire width direction D1, the distortion becomes a resistance to the road surface. Therefore, since the braking distance can be reduced, the braking performance can be improved.

  The first rubber portion 6a having a relatively low rubber hardness is disposed on the first side D11 in the tire width direction D1, while at least one of the belt layers 41 and 42 in the tire width direction D1. The centers 41c and 42c of the tire are located on the first side D11 in the tire width direction D1 than the tire equatorial plane S1. As a result, it is possible to suppress a difference in rigidity between the first side D11 and the second side D12 in the tire width direction D1. Therefore, when going straight, the first side D11 and the second side D12 in the tire width direction D1. It can suppress that the difference in grounding length arises between these.

  Moreover, in the pneumatic tire 1 according to the present embodiment, the second rubber portion 6b is configured to be disposed on the outer side when the vehicle is mounted.

  According to such a configuration, the second rubber portion 6b having a relatively large rubber hardness is arranged at the time of mounting on the vehicle, while the ground contact area of the outer area at the time of mounting on the vehicle becomes large at turning. . As a result, the rigidity of the outer region can be increased when the vehicle is mounted, so that the steering stability during turning can be improved.

  Further, in the pneumatic tire 1 according to the present embodiment, all the belt layers 41 and 42 overlap with the ground contact end 2c of the second side D12 in the tire width direction D1 in the tire radial direction D2.

  According to such a configuration, at least one of the belt layers 41 and 42, the centers 41c and 42c in the tire width direction D1 are located on the first side D11 in the tire width direction D1 than the tire equatorial plane S1. In contrast, all the belt layers 41 and 42 overlap the ground contact end 2c of the second side D12 in the tire width direction D1 in the tire radial direction D2. As a result, all the belt layers 41 and 42 overlap the outer ground contact end 2c in the tire radial direction D2 at the time of wearing the vehicle, so that it is possible to suppress a decrease in the rigidity of the outer region at the time of wearing the vehicle.

  The pneumatic tire 1 according to the present embodiment includes a plurality of land portions 3c to 3e divided by the plurality of main grooves 3a and 3b and the ground contact end 2b and 2c, and is configured by the first rubber portion 6a. The void ratio of land portions 3c to 3e is smaller than the void ratio of land portions 3c to 3e formed of the second rubber portion 6b.

  According to such a configuration, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a having a relatively small rubber hardness is the same as the land ratio formed of the second rubber portion 6b having a relatively large rubber hardness. It is smaller than the void ratio of the portions 3c to 3e. Thus, it is possible to suppress an increase in the difference in rigidity between land portions 3c to 3e on the first side D11 in the tire width direction D1 and land portions 3c to 3e on the second side D12.

  The pneumatic tire 1 according to the present embodiment is provided with a center land portion 3e including the tire equatorial plane S1 by being divided by the plurality of main grooves 3a and 3b, and the interface 6c is the center land. It is the structure of being located in the part 3e.

  According to such a configuration, since the interface 6c is located at the center land portion 3e, distortion generated at the interface 6c is a direct resistance to the road surface. Moreover, since the interface 6c is located at the center land portion 3e closest to the tire equatorial plane S1 against the contact pressure at the time of braking becoming larger as the tire equatorial plane S1 gets closer, strain generated at the interface 6c However, it is an effective resistance against the road surface.

  In addition, the pneumatic tire 1 is not limited to the structure of embodiment mentioned above, Moreover, it is not limited to the effect mentioned above. Of course, the pneumatic tire 1 can be variously modified without departing from the scope of the present invention. For example, as a matter of course, one or a plurality of configurations, methods, and the like according to various modifications described below may be arbitrarily selected and adopted as the configuration, method, and the like according to the above-described embodiment.

(1) In the pneumatic tire 1 according to the above embodiment, the center 41c of the first belt layer 41 and the center 42c of the second belt layer 42 have the same position in the tire width direction D1. . However, the pneumatic tire 1 is not limited to such a configuration. For example, as shown in FIG. 9, the center 41 c of the first belt layer 41 and the center 42 c of the second belt layer 42 may have different positions in the tire width direction D1.

  In the pneumatic tire 1 according to FIG. 9, the belt portion 4 includes a first belt layer 41 and a second belt layer 42 disposed outside the first belt layer 41 in the tire radial direction D2. The center 42c of the second belt layer 42 in the tire width direction D1 is positioned on the first side D11 of the tire width direction D1 with respect to the center 41c of the first belt layer 41 in the tire width direction D1. It is. That is, the distance W2 between the center 42c of the second belt layer 42 and the tire equatorial plane S1 is larger than the distance W1 between the center 41c of the first belt layer 41 and the tire equatorial plane S1.

  According to such a configuration, the second belt layer 42 located on the outer side in the tire radial direction D2 is larger than the rigidity of the rubber surface layer portion 6 than the first belt layer 41 located on the inner side in the tire radial direction D2. On the other hand, the center 42c of the second belt layer 42 in the tire width direction D1 is located on the first side D11 of the tire width direction D1 than the center 41c of the first belt layer 41 in the tire width direction D1. ing. Thereby, it is possible to effectively suppress the occurrence of a difference in the rigidity between the first side D11 and the second side D12 in the tire width direction D1 in the rubber surface layer portion 6.

  Therefore, for example, it is possible to effectively suppress the difference in the contact length between the first side D11 and the second side D12 in the tire width direction D1. The present invention is not limited to such a configuration, and for example, the center 41c of the first belt layer 41 may be positioned closer to the first side D11 in the tire width direction D1 than the center 42c of the second belt layer 42.

(2) Further, in the pneumatic tire 1 according to the embodiment, the centers 41c and 42c of all the belt layers 41 and 42 are positioned on the first side D11 in the tire width direction D1 than the tire equatorial plane S1. , Is a configuration. However, the pneumatic tire 1 is not limited to such a configuration. For example, as shown in FIG. 10, only the center 42c of one belt layer 42 among the plurality of belt layers 41 and 42 is located on the first side D11 in the tire width direction D1 than the tire equatorial plane S1. It may be a configuration.

(3) Moreover, in the pneumatic tire 1 according to the above-described embodiment, the second rubber portion 6b is arranged outside when the vehicle is mounted. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable. For example, the second rubber portion 6b may be arranged inside when the vehicle is mounted.

(4) Further, in the pneumatic tire 1 according to the above embodiment, all the belt layers 41 and 42 overlap the ground contact end 2c of the second side D12 in the tire width direction D1 in the tire radial direction D2. It is. However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable. For example, at least one second end 41b, 42b of the plurality of belt layers 41, 42 is located inside the tire width direction D1 than the second ground end 2c of the second side D12 in the tire width direction D1. Configuration may be used.

(5) Further, in the pneumatic tire 1 according to the above embodiment, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a is the land portions 3c to 3e formed of the second rubber portion 6b. Is smaller than the void ratio of However, the pneumatic tire 1 is not limited to such a configuration although such a configuration is preferable.

  For example, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a may be the same as the void ratio of the land portions 3c to 3e formed of the second rubber portion 6b. For example, the void ratio of the land portions 3c to 3e formed of the first rubber portion 6a may be larger than the void ratio of the land portions 3c to 3e formed of the second rubber portion 6b.

(6) Further, the pneumatic tire 1 according to the above-described embodiment is configured to be a tire whose mounting direction to the vehicle is designated. However, the pneumatic tire 1 is not limited to such a configuration. For example, the pneumatic tire 1 may be configured to be a tire whose mounting direction to a vehicle is not designated. In such a configuration, the tread pattern has a shape that is point symmetrical with respect to an arbitrary point on the tire equator, or a shape that is symmetrical with respect to the tire equator.

  A preferred embodiment of the tire 1 will be described below with reference to FIGS. 11 and 12.

<Crack occurrence rate>
Each tire is mounted on a vehicle, and after traveling 100,000 km on a general road under an internal pressure of 200 kPa, a crack is generated on the outer surface of the tire (a position near the first end 41a of the first belt layer 41) The possibility of the occurrence of cracks was calculated.

<Air contamination rate>
Twenty tires are manufactured, and the tires are cut along the tire meridional plane, and air is mixed in between the end portions 41a and 42a (41b and 42b) of the belt layers 41 and 42, and the air is mixed therein. The number of products was investigated to calculate the probability that air-containing products were generated.

Example 1
The tire according to Example 1 is a tire according to the above embodiment, and is a tire having the following configuration.
The distance W3 between the first end 41a of the first belt layer 41 and the tire surface: 10 mm
The distance W4, W6: 8 mm between the end 41a, 41b of the first belt layer 41 and the end 42a, 42b of the second belt layer 42

Examples 2 and 3
The tire according to the second embodiment is a tire obtained by moving the belt layers 41 and 42 to the first width direction D11 by about 2 mm from the tire according to the first embodiment. Therefore, in the tire according to Example 2, the distance W3 between the first end 41a of the first belt layer 41 and the tire surface is 8 mm.
The tire according to the third embodiment is a tire obtained by moving the belt layers 41 and 42 to the first width direction D11 by about 5 mm with respect to the tire according to the first embodiment. Therefore, in the tire according to Example 3, the distance W3 between the first end 41a of the first belt layer 41 and the tire surface is 5 mm.

Examples 4 and 5
In the tire according to the fourth embodiment, the dimension of the second belt layer 42 in the tire width direction D1 of the tire according to the first embodiment is increased by 3 mm in each of the first width direction D11 and the second width direction D12. It is a tire. Therefore, in the tire according to Example 4, the distances W4 and W6 between the end portions 41a and 41b of the first belt layer 41 and the end portions 42a and 42b of the second belt layer 42 are 5 mm.
The tire according to the fifth embodiment is a tire according to the tire according to the first embodiment, in which the dimension in the tire width direction D1 of the second belt layer 42 is increased by 5 mm in the first width direction D11 and the second width direction D12. It is. Therefore, in the tire according to Example 5, the distances W4 and W6 between the end portions 41a and 41b of the first belt layer 41 and the end portions 42a and 42b of the second belt layer 42 are 3 mm.

  As shown in FIG. 11, in the tire according to Example 3 in which the distance W3 between the first end 41a of the first belt layer 41 and the tire surface is 5 mm, the crack occurrence rate is 5%. In the tires according to Examples 1 and 2 in which the distance W3 is 8 mm or more, the crack occurrence rate is 0%. Accordingly, it is preferable that the distances W3 and W5 between the end portions 41a, 41b, 42a and 42b of the belt layers 41 and 42 and the tire surface be 8 mm or more.

  Further, as shown in FIG. 12, in the tire according to Example 5 in which the distance W4, W6 between the end portions 41a, 41b of the first belt layer 41 and the end portions 42a, 42b of the second belt layer 42 is 3 mm. In the tires according to the examples 1 and 4 in which the distances W4 and W6 are 5 mm or more, the air mixing rate is 0% with respect to the air mixing rate being 10%. Accordingly, it is preferable that the distances W4 and W6 between the end portions 41a and 41b of the first belt layer 41 and the end portions 42a and 42b of the second belt layer 42 be 5 mm or more.

  DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Tread part, 2a ... Tread surface, 2b ... 1st ground end, 2c ... 2nd ground end, 3 ... Tread rubber, 3a ... Shoulder main groove, 3b ... Center main groove, 3c ... Shoulder Land part, 3d: Middle land part (media land part), 3e: Middle land part (center land part), 3f: land groove (width groove), 3 g: land groove (sipe), 4: belt part, 5 ... Belt reinforcement part 6: rubber surface layer part 6a: first rubber part 6b: second rubber part 6c: interface: 7 rubber inner layer part 11: bead part 12: sidewall part 12a: sidewall rubber , 13: carcass layer, 14: inner liner layer, 20: rim, 41: first belt layer, 41a: first end, 41b: second end, 41c, center, 42: second belt layer, 42a,. 1st end, 42b ... 2nd end, 42c ... center, 51 Cap reinforcing layer 52: edge reinforcing layer 53: edge reinforcing layer D1: tire width direction D2: tire radial direction D3: tire circumferential direction D11: first width direction side (first side) D12: first 2 width direction side (second side), S1 ... tire equatorial plane

Claims (6)

A pneumatic tire comprising a plurality of main grooves extending in the tire circumferential direction, the pneumatic tire comprising:
A rubber surface layer portion having an outer surface in the tire radial direction, and a belt portion disposed on the inner side in the tire radial direction with respect to the rubber surface layer portion,
The rubber surface layer portion includes a first rubber portion formed of a first rubber, and a second rubber portion formed of a second rubber having a rubber hardness greater than that of the first rubber,
The first rubber portion is disposed on the first side in the tire width direction,
The second rubber portion is disposed on the second side in the tire width direction,
The interface between the first rubber portion and the second rubber portion is disposed between a pair of main grooves disposed at the outermost side in the tire width direction,
The belt portion comprises at least one belt layer,
A pneumatic tire, wherein the center in the tire width direction of at least one of the belt layers is positioned on the first side in the tire width direction with respect to the tire equatorial plane.   The pneumatic tire according to claim 1, wherein the second rubber portion is disposed outside when the vehicle is mounted.   The pneumatic tire according to claim 2, wherein all the belt layers overlap in the tire radial direction with the second ground end on the tire width direction. A plurality of land portions defined by the plurality of main grooves and the ground end;
The air-filled according to any one of claims 1 to 3, wherein the void ratio of the land portion formed of the first rubber portion is smaller than the void ratio of the land portion formed of the second rubber portion. tire. The belt portion includes a first belt layer, and a second belt layer disposed on the outer side in the tire radial direction than the first belt layer.
The center in the tire width direction of the second belt layer is positioned on the first side in the tire width direction with respect to the center in the tire width direction of the first belt layer. Pneumatic tire. A center land portion including the tire equatorial plane is provided by being divided by the plurality of main grooves,
The pneumatic tire according to any one of claims 1 to 5, wherein the interface is located at the center land portion.

Images