JP6190252B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that has improved uneven wear resistance particularly during circuit running while ensuring high drainage performance.

  As a method for improving the drainage performance of a tire, it is known that the circumferential groove is a straight groove, the number of circumferential grooves is increased, or the groove width is increased.

  However, when the number of circumferential grooves is increased, the width of the land portion defined by the circumferential grooves is reduced as the number of the circumferential grooves is increased, so that the rigidity of each land portion in the tire axial direction is greatly reduced. For this reason, in the category of sports tires where lateral grip during turning is important, a method of increasing the groove width instead of increasing the number of grooves is generally adopted to ensure lateral rigidity to withstand a large force in the tire axial direction. Has been.

  However, when trying to ensure sufficient drainage performance by the above method, this part is caused by receiving a strong force on the vehicle outer part at the outermost land part (shoulder land part) of the vehicle, especially during circuit driving. There is a problem that sufficient uneven wear resistance performance cannot be obtained, such as causing uneven wear.

  In addition, the thing of the following patent document 1 is proposed as a pneumatic tire which improved the uneven wear-proof performance at the time of circuit driving | running | working, ensuring high drainage performance.

JP 2004-338628 A

  The present invention is based on the fact that the outer circumferential groove arranged on the outermost side of the vehicle is formed by a zigzag groove having an amplitude larger than the groove width, while ensuring high drainage performance, particularly during circuit running. An object of the present invention is to provide a pneumatic tire with improved uneven wear resistance.

The present invention is a pneumatic tire having an inner grounding end located inside the vehicle and an outer grounding end located outside the vehicle by specifying the mounting direction to the vehicle,
An outer circumferential groove extending in the tire circumferential direction on the outermost contact end side in the tread portion,
A circumferential groove including an inner circumferential groove that forms a center rib that is arranged on the vehicle inner side and extends continuously in the tire circumferential direction with the outer circumferential groove;
Moreover, the outer circumferential groove is a zigzag groove, and the amplitude Zo of the zigzag is larger than the groove width Wo,
The inner circumferential groove is a zigzag groove or a linear groove, and in the case of a zigzag groove, the amplitude Zi of the zigzag is smaller than the amplitude Zo of the outer circumferential groove.

  In the pneumatic tire according to the present invention, the inner circumferential groove is preferably a straight groove.

  In the pneumatic tire according to the present invention, of the side edges of the center rib on the vehicle outer side, the inner point located on the innermost side of the vehicle is the outermost side edge of the center rib on the inner side of the vehicle. It is preferable to be located outside the vehicle from the point.

  In the pneumatic tire according to the present invention, the outer circumferential groove has a zigzag amplitude Zo of 0.12 to 0.20 times the ground contact width TW and a zigzag pitch number n of 12 to 19. preferable.

  In the pneumatic tire according to the present invention, the outer circumferential groove preferably has an angle θ of 5 to 20 ° with respect to the normal line of the tread surface of the groove wall surface.

  The contact width TW means the maximum width in the tire axial direction on the tread contact surface that contacts when a normal load is applied to a tire that is assembled with a normal rim and filled with a normal internal pressure. The contact end means the position of the end in the tire axial direction on the tread contact surface.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure defined by the standard for each tire. The maximum air pressure for JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for ETRA, Means "INFLATION PRESSURE", but in the case of passenger car tires, it is 180 kPa. The “regular load” is a load determined by the standard for each tire, and if it is JATMA, the maximum load capacity, and if it is TRA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” If it is ETRTO, it is "LOAD CAPACITY".

  In the present invention, as described above, the outer circumferential groove is formed as a zigzag groove having an amplitude larger than the groove width. Accordingly, the rigidity at the groove bottom is increased, and deformation of the tread portion starting from the groove bottom can be suppressed. That is, the movement of the shoulder land portion adjacent to the outer circumferential groove can be suppressed, and in particular, the uneven wear resistance performance of the shoulder land portion during circuit running can be improved.

  The outer circumferential groove is disadvantageous in drainage efficiency due to its large amplitude. However, in the present invention, since the inner circumferential groove is a linear groove or a zigzag groove whose amplitude is smaller than the amplitude of the outer circumferential groove, the disadvantage can be compensated for and high drainage while exhibiting the above effect. It becomes possible to ensure performance.

It is an expanded view of the tread pattern which shows one Example of the pneumatic tire of this invention. It is sectional drawing of an outer circumferential groove | channel. (A), (B) is a conceptual diagram explaining the effect by an outer circumferential groove | channel. It is an expanded view of the tread pattern of the other Example of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the pneumatic tire 1 of the present embodiment has a tread pattern that is asymmetrical to the left and right, and the grounding end TE of the tread portion 2 is located on the inner side of the vehicle by designating the mounting direction to the vehicle. The inner grounding end TEi located and the outer grounding end TEo located outside the vehicle are distinguished. In this example, a case is shown in which the pneumatic tire 1 is a high-performance tire premised on both road driving and race driving such as circuit competition and gymkhana competition.

  The tread portion 2 includes at least two circumferential grooves 3 extending in the tire circumferential direction. The circumferential groove 3 includes an outer circumferential groove 3o extending in the tire circumferential direction on the outermost ground contact end TEo side, and an inner circumferential groove 3i adjacent to the outer circumferential groove 3o on the vehicle inner side. .

  In this example, the case where the circumferential groove 3 is composed only of the inner and outer circumferential grooves 3i and 3o is shown. As a result, the tread portion 2 includes an outer shoulder land portion 4o outside the vehicle with respect to the outer circumferential groove 3o, a center land portion 4c between the inner and outer circumferential grooves 3i and 3o, and an inner circumferential groove 3o. Rather than the shoulder land portion 4i inside the vehicle.

  Of these, the center land portion 4c does not have a transverse groove or siping formed across the center land portion 4c, whereby the center land portion 4c is formed as a center rib 5 extending continuously in the tire circumferential direction. In this example, the center rib 5 extends on the tire equator C. On the other hand, in the present example, the outer shoulder land portions 4i, 4o are formed with lateral grooves 6i, 6o across the shoulder land portions 4i, 4o, and the blocks 7i, 7o are arranged in the circumferential direction, respectively. Formed as.

  Next, the outer circumferential groove 3o comprises a zigzag groove 8 extending in the circumferential direction while meandering in a zigzag shape, and the amplitude Zo of the zigzag is set larger than the groove width Wo. The zigzag shape includes a wave shape such as a sine curve. The groove width Wo is a width in the tire axial direction measured on the tread surface 2S, and hereinafter, the groove width of the circumferential groove 3 means this dimension.

  Here, as conceptually shown in FIGS. 3A and 3B, in the case of the zigzag groove Ga or the linear groove Gb whose amplitude Z is smaller than the groove width W, a straight line is provided in the circumferential direction in the groove bottom gs. There is a region gs1 extending in a shape. In this region gs1, the rigidity in the tire axial direction decreases stepwise, so that the tread portion 2 is easily bent and deformed starting from this region gs1. On the other hand, in the case of the zigzag groove 8, the deformation of the tread portion 2 is suppressed because the region gs1 does not exist. As a result, the movement of the outer shoulder land portion 4o adjacent to the outer circumferential groove 3o is suppressed, and in particular, the uneven wear resistance performance of the shoulder land portion 4o during circuit running can be improved.

  From the viewpoint of securing rigidity at the groove bottom, the difference (Zo−Wo) between the amplitude Zo and the groove width Wo is preferably 1 mm or more, more preferably 5 mm or more. If the amplitude Zo of the zigzag groove 8 is too large, and if the number of zigzag pitches n is too large, the resistance of water during drainage will increase, leading to a decrease in drainage efficiency. Further, when the amplitude Zo is too small, the groove width Wo inevitably becomes small accordingly, leading to a decrease in drainage efficiency. On the other hand, when the pitch number n is too small, it approaches a straight groove and the region gs1 tends to be formed in the ground contact surface, so that the effect of improving uneven wear resistance is reduced. From such a viewpoint, the amplitude Zo is preferably in the range of 0.12 to 0.20 times the ground contact width TW, and the pitch number n is preferably in the range of 12 to 19. In particular, in the amplitude Zo, the lower limit value is more preferably 0.14 times or more of the ground contact width TW, and the upper limit value is more preferably 0.18 times or less. In the pitch number n, the lower limit is more preferably 14 or more, and the upper limit is preferably 17 or less.

  Next, the inner circumferential groove 3i is formed from a zigzag groove 9 (shown in FIG. 1) or a straight groove 10 (shown in FIG. 4). In this example, the case where the inner circumferential groove 3 i is formed of a zigzag groove 9 is illustrated. In the case of the zigzag groove 9, the zigzag amplitude Zi is set smaller than the amplitude Zo of the outer circumferential groove 3o.

  This is disadvantageous in drainage efficiency due to the large amplitude Zo in the outer circumferential groove 3o. However, in the present invention, the inner circumferential groove 3i is the zigzag groove 9 or the linear groove 10 having a small amplitude Zi, so that the disadvantage is compensated for and high drainage performance is ensured as a whole tire.

  In the center land portion 4c (center rib 5) and the inner shoulder land portion 4i, the force in the tire axial direction acting during turning is smaller than that of the outer shoulder land portion 4o. Therefore, even if the zigzag groove 9 or the linear groove 10 having a small amplitude Zi is used for the inner circumferential groove 3i, the above-described effect of improving the uneven wear resistance can be maintained.

  From this point of view, the amplitude Zi of the inner circumferential groove 3i is preferably smaller than the groove width Wi, and in particular, the amplitude Zi is zero (0), that is, the linear groove 10 shown in FIG. Is more preferable. In the case of the zigzag groove 9, the pitch number n is preferably the same as and in phase with the pitch number n of the zigzag groove 8 in order to suppress uneven wear in the center land portion 4 c (center rib 5). .

  In this example, among the side edges eo on the vehicle outer side of the center land portion 4c (center rib 5), the inner point P1 located on the innermost side of the vehicle is the side edge ei on the vehicle inner side of the center land portion 4c (center rib 5). Among these, it is located on the vehicle outer side than the outer point P2 located on the outermost vehicle side. Thereby, the rigidity of the center land portion 4c (center rib 5) is ensured, and the straight traveling performance and the uneven wear performance are improved. The tire axial distance L between the inner point P1 and the outer point P2 at this time is preferably 1 mm or more, and more preferably 5 mm or more.

  As shown in FIG. 2, in the outer circumferential groove 3o of this example, the groove wall surface 3S has an angle θ of 5 to 20 ° with respect to the normal line of the tread surface 2S in a cross section perpendicular to the length direction. Tilt. Further, the groove wall surface 3S of the inner circumferential groove 3i is also inclined at the angle θ in the above range.

  Further, in this example, the lateral grooves 6i and 6o have an angle α with respect to the tire circumferential direction in the range of 70 to 110 °, and extend from the top of the zigzag tire axially outside beyond the ground contact end TE. Yes. The lateral grooves 6i and 6o may be curved in an arc shape, and in this case, the angle of the tangent line makes the above range. Such lateral grooves 6i, 6o maintain the lateral rigidity of the blocks 7i, 7o, and enhance drainage performance while ensuring lateral grip properties during turning.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

In order to confirm the effect of the present invention, a passenger car radial tire (225 / 45R17) having the tread pattern shown in FIGS. 1 and 2 as a basic pattern was prototyped according to the specifications shown in Table 1, and the drainage performance and uneven wear resistance performance were evaluated. Tested. Except as described in Table 1, the specifications are substantially the same. The formation positions of the circumferential grooves and the lateral grooves are the same.
(Common specifications)
・ Inner and outer circumferential grooves:
Groove depth: 6.0 mm,
Groove wall angle θ: 15 °,
・ Inner and outer lateral grooves Groove width: 6.5mm,
Groove depth: 6.0 mm,

(1) Drainage performance:
A tire with rim (7.5JJ-17) and internal pressure (220 kPa) mounted on all wheels of a vehicle (displacement 2000cc2), a 100m radius asphalt road surface with a water pool of 10mm in depth and 20m in length Above, the vehicle was made to enter while gradually increasing the speed, the lateral acceleration (lateral G) was measured, and the average lateral G of the front wheels at a speed of 50 to 80 km / h was calculated. The results were expressed as an index with Comparative Example 1 as 100. The larger the value, the better the drainage performance.

(2) Uneven wear resistance performance:
Using the vehicle, the test course was run for 30 km by marginal running, and the occurrence of uneven wear on the outer shoulder land was visually observed and displayed as an index with Comparative Example 1 taken as 100. The larger the value, the better the uneven wear resistance.

  As shown in Table 1, it can be confirmed that the tires of the examples can improve the uneven wear resistance performance while ensuring high drainage performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Circumferential groove 3o Circumferential groove 3S in the outer circumferential groove 3i Groove wall surface 5 Center rib 8 Zigzag groove 9 Zigzag groove 10 Straight groove ei, eo Side edge P1 Inner point P2 Outer point TEi Inside ground end TEo Outside ground end

Claims (5)

By specifying the mounting direction to the vehicle, a pneumatic tire having an inner grounding end located inside the vehicle and an outer grounding end located outside the vehicle,
An outer circumferential groove extending in the tire circumferential direction on the outermost contact end side in the tread portion,
A circumferential groove including an inner circumferential groove that forms a center rib that is arranged on the vehicle inner side and extends continuously in the tire circumferential direction with the outer circumferential groove;
Moreover, the outer circumferential groove is a zigzag groove, and the amplitude Zo of the zigzag is larger than the groove width Wo,
The inner circumferential groove is a zigzag groove or a linear groove, and in the case of the zigzag groove, the amplitude Zi of the zigzag is smaller than the amplitude Zo of the outer circumferential groove. .   The pneumatic tire according to claim 1, wherein the inner circumferential groove is a straight groove.   Of the side ribs on the vehicle outer side of the center rib, the inner point located on the innermost side of the vehicle is located on the outer side of the vehicle on the outer side of the center rib on the inner side of the vehicle. The pneumatic tire according to claim 1 or 2, characterized by the above.   The outer circumferential groove has a zigzag amplitude Zo of 0.12 to 0.20 times the ground contact width TW and a zigzag pitch number n of 12 to 19. The pneumatic tire according to Crab. The pneumatic tire according to claim 1, wherein the outer circumferential groove has an angle θ of 5 to 20 ° with respect to a normal line of a tread surface of the groove wall surface.

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