JP5829719B2 - Heavy duty pneumatic tire - Google Patents

Description

  The present invention relates to a tire used for a heavy-duty vehicle such as a truck or a bus, which is excellent in both fuel efficiency and drainage performance.

  In general, a heavy-duty pneumatic tire used in a heavy-duty vehicle such as a truck or a bus has, for example, a plurality of circumferential main grooves extending along the tire circumferential direction on a tread surface as shown in FIG. A tire having a so-called rib pattern in which a plurality of rib-like land portions are defined, and a plurality of circumferential main grooves extending along the tire circumferential direction and a tire width direction along a tread portion tread surface. And a tire having a so-called block pattern in which a plurality of block land portions are defined by disposing a main groove extending in the width direction.

  The tire with the rib pattern has a short total length when the total opening of the grooves and sipes to be arranged is short, so there are few edge components present in the tire contact surface, and improvement in drainage performance due to the edge effect cannot be expected, It is possible to ensure drainage performance by increasing the width of the circumferential main groove. In addition, with regard to the reduction of rolling resistance related to fuel efficiency, the rib-like land portions are integrally connected in the tire circumferential direction, so that the land portion rigidity against the input in the circumferential direction acting during driving and braking is high. Although the amount of deformation of the part can be suppressed, the rib-shaped land parts are separated by wide circumferential main grooves for the input in the tire width direction that acts during turning, etc. There is a tendency that the amount tends to increase to some extent, and when viewed comprehensively, there is a problem that the rolling resistance cannot be reduced sufficiently.

  As a tire having a rib pattern that achieves both improvement of drainage performance and reduction of rolling resistance, for example, in Patent Document 1, a rib-shaped land portion extends 0.5 to 1.5 mm across the tire width direction. A plurality of widthwise narrow grooves having a groove width of about a degree are further provided to form a rib-like land portion as a block-like land portion, and further to the block-like land portion in the width direction relative to the tire axial direction. A pneumatic tire having a tread pattern in which a closed sipe inclined in a direction opposite to the narrow groove is provided is described.

  The pneumatic tire described in Patent Document 1 has an edge that exists in the tire ground contact surface by disposing a widthwise narrow groove or a closed sipe in the rib-like land portion instead of widening the groove width of the circumferential main groove. Although the component is effectively increased and drainage performance is improved, the rib-like land portion is partitioned into block-like land portions by arranging the widthwise narrow grooves, so that each block-like land portion Is substantially divided by the narrow grooves in the width direction, the rigidity to the input in the tire width direction is lowered, and accordingly, the deformation amount of the block-shaped land portion in the tire width direction is increased. The effect of reducing rolling resistance is not sufficient, and there is room for further improvement.

  On the other hand, a tire having a block pattern is advantageous in terms of drainage performance because each block land portion is partitioned by a circumferential main groove and a width main groove, and therefore there are many edge components in the tire ground contact surface. However, the block land portions adjacent to each other across the circumferential main groove and the width direction main groove only show the rigidity of the individual block land portions without contacting each other at the time of tire contact, and the rigidity of the block land portion itself is Since it is small and the deformation amount is large, there is a problem that the rolling resistance increases.

JP 2000-177333 A

  An object of the present invention is to provide a heavy-duty vehicle such as a truck or a bus that is excellent in both fuel efficiency and drainage performance by appropriately partitioning a land portion located in a central area of a tread portion tread with various narrow grooves. It is providing the tire used for.

In order to achieve the above object, the present invention provides a heavy duty pneumatic tire, wherein the tread portion tread surface has a width corresponding to 40 to 65% of the tread width TW, centering on the tire equator E. The region is a region divided by a pair of circumferential main grooves that extend along the tire circumferential direction with the tire equator E interposed therebetween, and the land portion located in the region of the tread tread surface is a narrow groove. partitioned only, the fine grooves, when the tire is grounded, the and the tread portion opening of the thin groove that are disposed in the region of the tread surface which closes all, at least one of said narrow grooves, along the tire circumferential direction At least one circumferential narrow groove extending at least, and at least two or more central rib-shaped land portions are defined in the tread portion tread area, and the opening of the circumferential narrow groove is closed when the tire contacts the ground. In In addition, the central rib-like land portions located adjacent to each other across the circumferential narrow groove are in contact with each other and supported, and the circumferential narrow groove is circumferentially bent in the width direction alternately. The heavy-duty pneumatic tire is characterized in that the shape extends along the circumferential direction, and the shape is different from the shape that extends along the circumferential direction of the circumferential main groove .

  In the present invention, the central rib-shaped land portion is further provided with a plurality of widthwise narrow grooves extending transversely in the tire width direction, and the central rib-shaped land portion is defined as a central block-shaped land portion. It is preferable that the center block land portions located adjacent to each other are in contact with each other and support each other by closing the openings of the circumferential narrow groove and the width narrow groove when grounding.

  Furthermore, in this invention, it is preferable that the groove widths of the width direction narrow groove and the circumferential direction narrow groove are both 3 mm or less.

  Furthermore, in the present invention, it is preferable that a plurality of width direction main grooves extending transversely in the tire width direction are arranged in the side region, and a plurality of side block land portions are partitioned. In addition, it is more preferable to arrange a raised shallow bottom portion that connects the side block land portions located adjacent to each other across the width direction main groove in the width direction main groove. The ridge shallow bottom portion has an extension length of 0.3 to 0.8 times the width of the side block land portion, and a height of 0.5 to 0.8 times the groove depth of the width direction main groove. A range is preferred.

According to the present invention, a heavy load such as a truck or a bus, which is excellent in both fuel efficiency and drainage performance, by properly partitioning a land portion located in the central region of the tread portion tread with only various narrow grooves. It has become possible to provide tires for use in vehicles.

FIG. 3 is a development view of a part of a tread portion of a heavy-duty pneumatic radial tire according to the present invention. FIG. 6 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 5 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 5 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 5 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 5 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 5 is a partial development view of a tread portion of another heavy-duty pneumatic radial tire according to the present invention. FIG. 6 is a development view of a part of a tread portion of a conventional heavy-duty pneumatic radial tire.

Next, embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a part of a tread portion (tread pattern) of a heavy duty pneumatic tire according to the present invention.

  The heavy-duty pneumatic tire having the tread portion 1 shown in FIG. 1 has a pair of circumferential main grooves 2a and 2b extending along the tire circumferential direction C on the tread portion 1 with the tire equator E interposed therebetween. It is set. The pair of circumferential main grooves 2a and 2b are arranged at positions where the tread surface of the tread portion 1 is divided into a central area 3 and both lateral areas 4a and 4b.

  The “central region” here means a region of the tread portion tread having a width corresponding to 40 to 65% of the tread width TW with the tire equator E as the center, and the “lateral region” The tread portion tread area is located on the outer side in the tire width direction of the central region 3 across the circumferential main grooves 2a and 2b, and is divided by the circumferential main groove 2a or 2b and the tread end 5a or 5b. .

And, the main feature of the configuration of the present invention is to properly partition the land portion located in the central region 3 of the tread portion tread with only various narrow grooves, specifically, in the central region 3, At least one circumferential narrow groove 6 extending along the tire circumferential direction C, three circumferential narrow grooves 6a, 6b, 6c in FIG. In FIG. 1, four central rib-like land portions 7a, 7b, 7c, 7d are defined, and the circumferential narrow grooves 6a, 6b, 6c are closed when the tire contacts the ground, thereby closing the circumferential narrow grooves. 6a, 6b, and 6c are located adjacent to each other, and the central rib-like land portions 7a and 7b, 7b and 7c, and 7c and 7d (the opposite side walls) are in contact with each other to support each other. By adopting this configuration, both fuel efficiency and drainage performance can be improved.

That is, according to the present invention, by arranging a pair of relatively wide circumferential main grooves 2a and 2b which are divided into the central region 3 and the lateral regions 4a and 4b, the drainage is ensured. 3, at least one circumferential narrow groove 6a, 6b, 6c extending along the tire circumferential direction C is disposed, and at least two or more central rib-shaped land portions 7a, 7b, 7c are disposed. 7d, the tires are placed adjacent to each other across the circumferential narrow grooves 6a, 6b, 6c as the openings of the circumferential narrow grooves 6a, 6b, 6c close when the tire contacts the ground. The central rib-shaped land portions 7a, 7b, 7c, 7d that are in contact with each other and support each other, whereby the central rib-shaped land portions 7a and 7b, 7b and 7c, and 7c and 7d that are located in the central region 3 However, when the tire touches the ground, the adjacent central rib-shaped land not only for the input in the tire circumferential direction C but also for the input in the tire width direction W. 7a and 7b, 7b and 7c, 7c and 7d can be opposed to each other as a result, the amount of deformation of the land portions 7a to 7d located in the central region 3 regardless of the input from any direction Can effectively suppress the rolling resistance. The term “when the tire is in contact with the ground” as used herein specifically refers to the time when the tire is mounted on a regular rim, set to a regular internal pressure, placed in a stationary state perpendicular to the flat plate, and loaded with a regular load. means. Here, the regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is the maximum load capacity specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “LOAD CAP” specified by ETRTO.
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  The groove widths of the circumferential main grooves 2a and 2b are preferably 5 mm or more from the viewpoint of ensuring drainage. On the other hand, if the groove width of the circumferential main grooves 2a and 2b is wider than 30 mm, the area ratio of the tread land portion located in the tire contact area becomes too low (negative ratio is large), and the wear performance is deteriorated. It becomes easy to do. For this reason, the upper limit of the groove width of the circumferential main grooves 2a and 2b is preferably 30 mm.

  As shown in FIG. 1, the extending shape of the circumferential main grooves 2a and 2b is made to be a zigzag shape or a corrugated shape. Although it may be arranged in a straight line, it is not necessary that the circumferential main grooves 2a and 2b have the same zigzag shape. It is also possible to arrange with a wavelength.

  The groove width of the circumferential narrow grooves 6a, 6b, 6c is 3 mm or less in order to prevent the rolling resistance from increasing by making the width close to the opening at the time of tire contact (when rolling the tire load). It is preferable to do. On the other hand, if the groove width of the circumferential narrow grooves 6a, 6b, 6c is smaller than 0.5 mm, the drainage improvement effect is not recognized as compared with the rib-like land portion where the circumferential narrow grooves are not provided. The lower limit value of the groove width of the direction narrow grooves 6a, 6b, 6c is preferably 0.5 mm.

  In addition, as shown in FIG. 1, the extending shape of the circumferential narrow grooves 6a, 6b, 6c increases the edge component in the width direction to increase driving / braking performance and drainage performance. It is preferable in that it can be improved, but it may be linear, it is not necessary to make the zigzag shape of each circumferential narrow groove 6a, 6b, 6c the same, it is shifted by a half pitch in the circumferential direction, It can also be arranged at a wavelength.

  In the case where the extending shape of the circumferential narrow grooves 6a, 6b, 6c is a zigzag shape, two narrow groove portions 10a extending alternately in different directions at an angle θ1 within a range of ± 50 ° with respect to the tire circumferential direction, 10b is preferable. This is because when the angle θ1 exceeds ± 50 °, the corners of the land portions are angular, the rigidity of the corner portions of the land portions is reduced, and problems such as rubber chipping may occur.

  Further, in the present invention, as shown in FIG. 2, a plurality of widthwise narrow grooves 8a, 8b, 8c, 8d extending transversely in the tire width direction W are further arranged in the central rib-like land portions 7a-7d. Then, the central rib-shaped land portion is defined as a central block-shaped land portion 9a, 9b, 9c, 9d, and at the ground, the openings in the circumferential narrow grooves 6a to 6c and the width-direction narrow grooves 8a to 8d are formed. By closing, the central block-shaped land portions 9a to 9d located adjacent to each other with the circumferential narrow grooves 6a to 6c and the width narrow grooves 8a to 8d interposed therebetween may have a configuration in which they support and support each other. It is preferable in that the rigidity of the land portion located in the central region 3 is maintained and the deformation of the central block-shaped land portions 9a to 9d is suppressed, and the edge component is effectively increased to further improve the drainage performance. In FIG. 2, for convenience of explanation, each one central block land portion 9a to 9d is shown as a hatched portion.

The width of the narrow grooves 8a to 8d in the width direction is preferably 3 mm or less in order to prevent the rolling resistance from increasing by making the width close to the opening at the time of tire contact (when rolling the tire). More preferably, it is 1.5 mm or less. On the other hand, if the groove width of the circumferential narrow grooves 6a, 6b, 6c is smaller than 0.5 mm, the drainage improvement effect is not recognized as compared with the rib land portion where the circumferential narrow grooves are not provided. The lower limit value of the groove width of the direction narrow grooves 6a, 6b, 6c is preferably 0.5 mm.
The extending direction of the width direction narrow grooves 8a to 8d is 55 to 125 with respect to the tire circumferential direction in order to ensure the rigidity of the corner portion of the land portion defined by the width direction narrow grooves 8a to 8d and to avoid rubber chipping. A range of ° is preferable.

  Further, in the present invention, in order to further increase the edge component, as shown in FIG. 2, the width direction auxiliary narrow grooves 11a to 11d extending in a crank shape in the tire width direction are formed in the respective central block-shaped land portions 9a to 9d. It is arranged and divided into two small block land portions, and each small block is shown with one width direction sub-thin groove 12 extending in the tire width direction and terminating in the land portion. However, such a configuration can be provided as needed.

  Further, in the present invention, as shown in FIG. 2, a plurality of width direction main grooves 13a, 13b extending transversely in the tire width direction W are arranged on the (rib) land portions located in the side regions 4a, 4b. And a plurality of side block land portions 14a and 14b may be partitioned to improve the drainage performance to the side of the tire. In addition, it is preferable that the groove width of the width direction main grooves 13a and 13b is in the range of 4 to 18 mm. If the groove width of the main grooves 13a and 13b in the width direction is less than 3 mm, the effect of improving drainage to the side of the tire is not sufficient, and if the groove width is wider than 18 mm, the ground contact area is reduced and the steering stability is reduced. As the side block land portions 14a and 14b become smaller and the land portion rigidity decreases, the side block land portions 14a and 14b tend to deform and the rolling resistance tends to increase. It is. The extending direction of the width direction main grooves 13a, 13b is preferably in the range of ~ ° with respect to the tire circumferential direction.

  In addition, in the present invention, the lateral shallow land portions 14a and 14a, 14b and 14b, which are located adjacent to the width direction main grooves 13a and 13b with the width direction main grooves 13a and 13b interposed therebetween, are shallowly raised. It is preferable to dispose the bottom portion 15. With this configuration, the land portion deformation of the side block land portions 14a and 14b can be effectively suppressed without deteriorating the drainage performance.

  The raised shallow bottom portion 15 has an extension length L of 0.3 to 0.8 times the width of the side block land portions 14a and 14b, and the bottom positions of the width-direction main grooves 13a and 13b of the raised shallow bottom portion 15 Is preferably in the range of 0.5 to 0.8 times the groove depth of the width direction main groove. If the extending length L of the raised shallow bottom portion 15 is less than 0.3 times the width of the side block land portions 14a and 14b, the land block rigidity of the side block land portions 14a and 14b is insufficient and uneven wear occurs. Also, if the extended length L of the raised shallow bottom portion 15 exceeds 0.8 times the width of the side block land portions 14a, 14b, the edge component at the end of tire use will be insufficient. This is because the drainage performance to the side may be significantly reduced. If the height of the raised shallow bottom portion 15 is less than 0.5 times the depth of the main groove in the width direction, the block rigidity is reduced, and uneven wear tends to occur. If the depth exceeds 0.8 times the groove depth of the width direction main groove, there is a tendency that the effect of improving drainage performance to the side of the tire due to the arrangement of the width direction main grooves 13a, 13b cannot be sufficiently obtained. Because there is.

  As another embodiment, as shown in FIGS. 3 to 5, two circumferential narrow grooves 6 a and 6 b are provided in the central region 3 of the tread surface 1 and three rib-shaped land portions or blocks are provided. A pair of circumferential main grooves 2a and 2b are arranged in a straight line as shown in FIG. 6, and three zigzag-shaped circumferential lines are provided in the central area 3 of the tread surface 1. A tire in which directional narrow grooves 6a, 6b, 6c are arranged to define four rib-like land portions or block-like land portion rows, as shown in FIG. 7, a pair of circumferential main grooves 2a, 2b In addition to being arranged in a zigzag shape, a straight central main groove 2c is further arranged at the tire equator position, and the land portion located in the central region 3 is divided into two by the central main groove 2c, and each circumferential main groove 2a, 2b and the central main groove 2c may be a tire that divides a land portion into two rib-like land portions 7a and 7b, 7c and 7d by circumferential narrow grooves 6a and 6b. State of Is mentioned.

  The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

Next, a heavy-duty pneumatic tire according to the present invention was prototyped and its performance was evaluated, which will be described below.
The tires of Examples 1 to 5 have a tire size of 315 / 70R22.5, and the configuration of the tread portion was produced as shown in Table 1. In the present invention, the tread pattern has structural features, and the other tire structures are the same as the conventional heavy-duty pneumatic tire. For comparison, a tire having a tire size of 315 / 70R22.5 and having a tread pattern as shown in FIG. 8 was also prototyped as a conventional tire.

(Test method)
About each said test tire, the tire was mounted | worn to the applicable rim (rim size: 9.00), and fuel consumption performance and drainage performance were evaluated.
Fuel efficiency is measured using a drum testing machine (speed: 80 km / h) with a steel plate surface with a diameter of 1.7 m, and the rolling resistance of the axle is measured under conditions of tire internal pressure: 900 kPa and load load: 3187.5 kgf. The rolling resistance was measured and evaluated. This rolling resistance measurement was performed in accordance with ISO18164 using a smooth drum and a force type.
Drainage performance is based on the feeling of a professional driver when turning round a 20m radius test course with a wet road surface of 30mm / h and a water depth of 2mm under conditions of tire internal pressure: 900kPa and load load: 3350kgf. evaluated.
Table 2 shows the evaluation results. In addition, the numerical values of the fuel consumption performance and the drainage performance in Table 2 are both shown as index ratios when the conventional tire is set to 100, and the larger the numerical value, the better the performance.

  From the results shown in Table 2, the tires of Examples 1 to 5 are equivalent to or better in drainage than the conventional tires, and have excellent fuel efficiency.

According to the present invention, a heavy load such as a truck or a bus, which is excellent in both fuel efficiency and drainage performance, by properly partitioning a land portion located in the central region of the tread portion tread with only various narrow grooves. It has become possible to provide tires for use in vehicles.

1 Tread part 2, 2a, 2b Circumferential main groove 3 Central area
4a, 4b lateral area
5a, 5b Tread end 6, 6a, 6b, 6c Circumferential narrow groove 7, 7a, 7b, 7c, 7d Central rib-shaped land 8, 8a, 8b, 8c, 8d Wide narrow groove 9, 9a, 9b, 9c 9d Central block land
10a, 10b Two narrow groove parts constituting the circumferential narrow groove
11, 11a, 11b, 11c, 11d Auxiliary narrow groove in the width direction
12 Sub-groove in the width direction
13a, 13b Width direction main groove
14a, 14b Side block land
15 Raised shallow bottom

Claims (2)

In the heavy-duty pneumatic tire, in the region of the tread portion tread having a width corresponding to 40 to 65% of the tread width TW, centering on the tire equator E,
The area of the tread portion tread area is an area divided by a pair of circumferential main grooves extending along the tire circumferential direction disposed across the tire equator E,
The land portion located in the tread portion tread area is partitioned only by a narrow groove, and the narrow groove closes all the narrow groove openings disposed in the tread portion tread area when the tire contacts the ground .
At least one of the narrow grooves is at least one circumferential narrow groove extending along the tire circumferential direction, and at least two or more central rib-shaped land portions are defined in the tread portion tread area. At the time of tire contact, when the opening of the circumferential narrow groove is closed, the central rib-shaped land portions located adjacent to each other across the circumferential narrow groove are narrow grooves that are in contact and support each other,
Further, the circumferential narrow groove has a shape extending along the circumferential direction while being alternately bent in the width direction, and the shape is different from a shape extending along the circumferential direction of the circumferential main groove. Heavy duty pneumatic tire. The heavy duty pneumatic tire according to claim 1, wherein the circumferential narrow groove has a groove width of 3 mm or less .

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