JP2006273124A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire suppressing generation of a ply steer, and also generation of crack from the bottom of a sipe. <P>SOLUTION: The pneumatic tire 10 comprises a carcass 14 laid in a toroidal shape over a pair of bead cores 12, a plurality of waved belt layers 15 arranged outside in a tire diameter direction of the carcass 14, and a tread portion 16 arranged outside in the tire diameter direction of the waved belt layer 15, and equipped with a land part 17 divided by at least two main grooves 13 extending in a tire circumferential direction. The waved belt layer 15 is a belt layer made from a plurality of cords 20 extending while meandering in the tire circumferential direction. A plurality of sipes 18 is formed on the land part 17 of the tread portion 16. The sipes 18 extend at an angle θ in a range of 0°±5° in regard to a tire width direction. Therefore, the whole of the sipes almost simultaneously steps into a ground surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire suitable as a main wheel of a vehicle such as a tire-running subway, a monorail, and a new transportation system.

  Tires have advantages such as lower noise levels, better acceleration and deceleration, and better ride comfort than metal wheels, so in recent years only tires such as monorails and new transportation systems have been used. It is also used for subway vehicles (see, for example, Patent Document 1).

  As shown in FIGS. 3 and 4, these tire traveling vehicles include a main wheel tire 72 that supports the load of the vehicle on a carriage 71 and a guide wheel tire 73 that guides the vehicle. Many. The main wheel tire 72 travels on a concrete main wheel road surface 74, and the guide wheel tire 73 travels on a concrete guide wheel road surface 75 formed vertically.

  When the vehicle turns a curve, the tire traveling direction of the main wheel tire 72 has an angle α as shown in FIG. 4 with respect to the carriage traveling direction. Therefore, since the slip angle is compulsorily given to the main wheel tire 72 by the guide wheel tire 73, cornering power characteristics become important in terms of tire performance.

Here, as shown in FIGS. 5 and 6, a conventional pneumatic tire 81 used for a main wheel is composed of a carcass 82 straddling a toroid between a pair of bead cores 83 and a tire circumferential direction. And an inclined belt layer 85 disposed outside the carcass 82 in the tire radial direction and a tread portion 86 disposed outside the inclined belt layer 85 in the tire radial direction. Have. The inclined belt layer 85 is composed of three layers. The width of the first layer 85A is 85% of the width of the tread portion 86 (however, the belt is hollow and the hollow width is 27 of the tread width). %) The width of the second layer 85B is 95% of the width of the tread portion 86, and the width of the third layer 85C is 85% of the width of the tread portion 86.
JP 2002-234111 A

  Incidentally, the conventional pneumatic tire 81 has a high cornering power characteristic value due to the influence of the three inclined belt layers 85. Therefore, when the conventional pneumatic tire 81 is used as the main wheel tire 72 shown in FIG. 4, among the four guide wheel tires 73, the load applied to the guide wheel tire 73A on the traveling direction side outside the curvature radius of the curve. Increases, and the load received by the road surface 75 for the guide wheel outside the curvature radius of the curve also increases. That is, there is a drawback that the durability life of the guide wheel tire 73A and the guide wheel road surface 75 is likely to be reduced.

In addition, when a pneumatic tire is used as the tire, the pressure is set to a high internal pressure of 9 kg / cm ² or more, so that there is a problem that the bottom portion of the sipe 88 provided in the tread portion 86 is easily cracked. This is because the distortion at the bottom of the sipe during internal pressure filling and load rolling increases, leading to cracking.

  As a countermeasure, in Patent Document 1, the cornering power characteristic value is reduced by providing a waved belt layer, and the extending direction of the sipe 88 is set within a range of 5 to 25 ° with respect to the tire width direction. It is proposed to suppress the occurrence of cracks from the sipe bottom.

  However, even a pneumatic tire for which such a proposal has been made has a problem that the occurrence of cracks at the sipe bottom cannot be sufficiently suppressed. This crack is likely to occur particularly at a position where the main groove and the sipe form an acute angle in the center rib. This problem is a problem that is desired to be solved even at the expense of wear resistance and knitting wear resistance.

  In addition, there has been a problem that price tearing occurs and the wear resistance of the one-side guide wheel tire deteriorates. The price tear is a force that moves to the right side or the left side in the tire traveling direction during rolling of the tire load. The main cause of the price tear is that the intersecting belt layers are twisted and sheared, but it is also caused by an asymmetric pattern.

  In view of the above fact, an object of the present invention is to provide a pneumatic tire that suppresses generation of price tears and suppresses generation of cracks from the sipe bottom.

  The present inventor has examined the cause of the occurrence of cracks at the sipe bottom in a conventional pneumatic tire. And I found out the following.

  Since the waved belt faces the tire circumferential direction and has high tire circumferential direction rigidity, it is necessary to make the ground contact shape a square in order to prevent uneven wear of the shoulder portion. In this case, a sipe having an angle of 5 to 25 ° with respect to the tire width direction will step into the ground contact surface at that angle, and in particular, distortion at the time of stepping concentrates on the sipe bottom that forms an acute angle with the main groove. .

  Therefore, the present inventor diligently studied a configuration for avoiding such strain concentration, repeated experiments, and completed the present invention.

  According to the first aspect of the present invention, a carcass straddling a toroidal shape between a pair of bead cores, a plurality of belt layers disposed on the outer side in the tire radial direction of the carcass, and an outer side in the tire radial direction of the belt layer. And a tread portion including a land portion defined by at least two main grooves extending along the tire circumferential direction, wherein the belt layer meanders along the tire circumferential direction. A plurality of sipes are formed on the land portion of the tread portion, and the sipe forms an angle within a range of 0 ° ± 5 ° with respect to the tire width direction. It is characterized by extending.

  Thus, in the first aspect of the invention, the belt layer is a waved belt layer, and the sipe extends at an angle within a range of 0 ° ± 5 ° with respect to the tire width direction.

  As a result, the entire sipe is stepped on the contact surface almost simultaneously, and the concentration of distortion at the sipe bottom when stepped on can be dispersed. Moreover, the price tear can be significantly reduced.

  ADVANTAGE OF THE INVENTION According to this invention, it can be set as the pneumatic tire which suppressed generation | occurrence | production of a price tear and also suppressed generation | occurrence | production of the crack from a sipe bottom.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention includes a carcass 14 straddling a toroidal shape between a pair of bead cores 12 and a plurality of waves disposed on the outer side in the tire radial direction of the carcass 14. The belt layer 15 (for example, three waved belt layers 15 </ b> A to 15 </ b> C) and the plurality of main grooves 13 that are disposed on the outer side in the tire radial direction of the waved belt layer 15 and extend along the tire circumferential direction. A pneumatic tire having a tread portion 16 including a land portion 17.

  As shown in FIG. 2, the waved belt layer 15 is a belt layer composed of a plurality of cords 20 that meander and extend along the tire circumferential direction. The cord 20 constituting the waved belt layer 15 has a value of (H / L) × 100, for example, 6.6, where the amplitude is H and the wavelength is L.

  Further, a plurality of sipes 18 are formed in the land portion 17 of the tread portion 16, and the sipes 18 extend at an angle θ within a range of 0 ° ± 5 ° with respect to the tire width direction.

  Thus, in the first aspect of the invention, the belt layer is a waved belt layer, and the sipe extends at an angle within a range of 0 ° ± 5 ° with respect to the tire width direction.

  As a result, the entire sipe is stepped on the contact surface almost simultaneously, and the concentration of distortion at the sipe bottom when stepped on can be dispersed. Therefore, the occurrence of cracks from the sipe bottom can be sufficiently suppressed even in the center rib as well as in the vicinity of the tread end T. In addition, the price tear can be significantly reduced.

  Here, the tread end means that a pneumatic tire is mounted on a standard rim prescribed by JATMA YEAR BOOK (2002 edition, Japan Automobile Tire Association Standard), and the maximum load in the applicable size and ply rating in JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost contact portion in the tire width direction when the maximum load capacity is applied. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

<Test example>
In order to confirm the effect of the present invention, the inventor has an example of a pneumatic radial tire 10 according to the above-described embodiment (hereinafter referred to as an example tire) and an example of a conventional pneumatic tire (hereinafter referred to as a conventional example). The tires were prepared and the performance was evaluated.

  The conventional tire is a tire having the above-mentioned angle θ of 15 ° (see FIG. 6). The tire of the example is a tire having an angle θ of 0 ° (see FIG. 2).

  In this test example, the tire sizes are all E315 / 70R20, and the applicable rim sizes are all 8.50Z-20. The internal pressure was tested at 1050 kPa.

  In this test example, for both tires, a load of 4500 kgf was applied on the drum, the lateral force was measured by rotating forward and reverse at a speed of 30 km / h with a slip angle of 0, and ½ of the difference Was price tear.

  In this test example, both tires were run for 100,000 km under conditions of a load of 4500 kgf and a speed of 60 km / h, and the number of cracks generated at the sipe bottom was measured and compared.

  And in performing performance evaluation, the evaluation in the tire of a conventional example was made into the index 100, and the index used as a relative evaluation was computed about the tire of the Example. The evaluation results are shown in Table 1. The smaller the index, the better the performance.

  As can be seen from Table 1, the tires of the examples were significantly better in both price tear and sipe bottom crack resistance than the conventional tires.

  The embodiments of the present invention have been described with reference to the embodiments. However, the above embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

1 is a tire radial direction cross-sectional view of a pneumatic tire according to an embodiment of the present invention. It is a plane sectional view showing the composition of the pneumatic tire concerning one embodiment of the present invention. It is a typical front view which shows the relationship between the tire of a tire traveling type vehicle, and a road surface. It is a top view which shows that the trolley | bogie of a tire traveling type vehicle advances. It is a tire radial direction sectional view of the conventional pneumatic tire. It is a plane sectional view showing the composition of the conventional pneumatic tire.

Explanation of symbols

10 Pneumatic tire 12 Bead core 13 Main groove 14 Carcass 15 Waved belt layer 16 Tread portion 17 Land portion 18 Sipe 20 Cord 80 Cord 81 Pneumatic tire 82 Carcass 83 Bead core 85 Inclined belt layer 86 Tread portion 88 Sipe

Claims (1)

A carcass straddling in a toroidal shape between a pair of bead cores, a plurality of belt layers disposed on the outer side in the tire radial direction of the carcass, and disposed at the outer side in the tire radial direction of the belt layer and extending at least along the tire circumferential direction In a pneumatic tire having a tread portion including a land portion partitioned by two main grooves,
The belt layer is a waved belt layer composed of a plurality of cords meandering along the tire circumferential direction,
A plurality of sipes are formed in the land portion of the tread portion, and the sipes extend at an angle within a range of 0 ° ± 5 ° with respect to the tire width direction. tire.

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