JP5993636B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire provided with a belt reinforcing layer formed by winding a rubber strip having a reinforcing cord covered with rubber in the tire circumferential direction.

  With the recent improvement in vehicle quality, especially in passenger cars, the reduction of vehicle vibration and the improvement of ride comfort are advancing rapidly. Further improvements in steering stability and reduction of road noise are also achieved for tires. It is requested. On the other hand, there is a strong demand for reducing rolling resistance on tires as the fuel efficiency of vehicles progresses.

  Conventionally, in order to maintain the shape of the tire during traveling and to suppress the deformation of the tread portion outward in the radial direction of the tire due to centrifugal force during high-speed traveling in particular, the outer peripheral side of the belt layer is improved. A pneumatic tire is known in which a belt reinforcing layer is formed by spirally winding a rubber strip covered with a reinforcing cord in the tire circumferential direction (see, for example, Patent Document 1).

  When a belt reinforcing layer as described above is provided on a pneumatic tire, the rigidity in the tire circumferential direction increases and the shape deformation during running decreases, reducing road noise and rolling resistance, and improving steering stability when going straight However, there are cases where the brake performance and steering stability during cornering cannot be sufficiently secured, and there is room for further improvement.

JP 2003-260906 A

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pneumatic tire capable of reducing road noise and rolling resistance, improving steering stability when traveling straight, and improving braking performance and steering stability during cornering. And

The present invention has been made to solve the above problems, and a pneumatic tire according to the present invention is provided with a belt comprising at least one belt layer in which a belt cord is rubber-coated, and on the outer side in the tire radial direction of the belt. A pneumatic tire having a belt reinforcing layer formed,
The belt reinforcing layer is made of rubber strip having a constant width extending helically in the tire circumferential direction, and has a close coiled portion in the region of the tire on one widthwise side to be classified by the tire equatorial plane, the tire width It has a roughly coiled portion in the region of the direction other side, winding pitch of the rubber strip in the close coiled portion, Ri Oh small than winding pitch of the rubber strip in the coarse winding portion, the close coiled portion And the width in the tire width direction of the rubber strip in the coarsely wound portion is constant in the range of 3 mm to 10 mm, and 3 to 6 reinforcing cords are 0.1 mm to 3 mm in the tire width direction on the rubber strip. The winding pitch of the rubber strip in the rough winding portion is 1.1 to 2 times the width of the rubber strip in the tire width direction. Winding pitch of the rubber strip in the can portion or 0.5 times the tire width direction of width of the rubber strip, it is characterized in that it is and less than 1.0 times. Here, in the present invention, the “winding pitch” refers to a distance in the tire width direction between the centers in the tire width direction of rubber strips adjacent to each other in the tire width direction in a sectional view in the tire width direction.

In such a pneumatic tire, the rigidity in the tire circumferential direction in the region on one side in the tire width direction is large, and the rigidity in the tire circumferential direction in the region on the other side in the tire width direction is small. By properly attaching such pneumatic tires to the vehicle and reducing road noise and rolling resistance, and improving steering stability when going straight, improving braking performance and steering stability during cornering Can do. In addition, since the rubber strips are arranged at intervals in the tire width direction in the rough winding portion, it is possible to reduce the weight and save resources. Furthermore, the winding pitch of the rubber strip in the tightly wound portion is equal to or less than the width in the tire width direction of the rubber strip, so that the rigidity in the tire circumferential direction on one side in the tire width direction can be more reliably increased, The steering stability, road noise, and rolling resistance can be reduced.

  In the pneumatic tire of the present invention, the winding pitch of the rubber strip is at least part of the belt reinforcing layer between the densely wound portion and the roughly wound portion, and It is preferable that the width gradually increases in the direction toward the coarsely wound portion. According to this, it is possible to suppress the occurrence of uneven wear by preventing a large rigidity step in the tire width direction.

  Further, in the pneumatic tire according to the present invention, the belt constitutes a cross belt layer including at least two belt layers in which the extending direction of the belt cord intersects each other, and the tire among the cross belt layers When the belt layer having the narrowest width in the width direction is defined as the narrowest belt layer, the tightly wound portion is at least the most narrow belt layer from the one end in the tire width direction toward the tire equatorial plane. Preferably formed in the tire width direction region up to 1/8 of the tire width direction width of the narrow belt layer, according to this, the cross belt layer width direction in which the reinforcing effect of the cross belt layer is not sufficiently obtained Insufficient rigidity near the end can be compensated, and steering stability, road noise, and rolling resistance during straight travel can be reduced more reliably.

  According to the present invention, it is possible to provide a pneumatic tire capable of reducing road noise and rolling resistance, improving steering stability when traveling straight, and improving braking performance and steering stability during cornering. .

It is sectional drawing of the tire width direction which shows the state which assembled | attached the tire of one Embodiment according to this invention to the regular rim, and was filled with the regular internal pressure. (A) is a figure which shows the belt and belt reinforcement layer of the tire of Example 1 according to this invention, (b) is a figure which shows the belt and belt reinforcement layer of the tire of Example 2, (c) is implementation. It is a figure which shows the belt and belt reinforcement layer of the tire of Example 3, (d) is a figure which shows the belt and belt reinforcement layer of the tire of a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A pneumatic tire (hereinafter also referred to as a tire) 1 according to an embodiment of the present invention shown in FIG. 1 shows a state in which the pneumatic tire is assembled to a regular rim R and filled with a regular internal pressure, and no load is applied. Here, 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 above "regular internal pressure" is the air pressure specified by the above standard for each tire. The maximum air pressure described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" is the maximum air pressure for JATMA and TRA for TRA. If it is ETRTO, it is "INFLATION PRESSURE".

  The tire 1 includes a bead portion 5 in which a pair of bead cores 3 and the like are covered with rubber, a pair of sidewall portions 7 extending outward in the tire radial direction from the bead portion 5, and a tread portion 9 straddling the pair of sidewall portions 7. Prepare. The carcass 11 extends in a toroidal shape between the pair of bead cores 3 and is folded back from the inside to the outside of the tire around the bead cores. A belt 13 including at least one belt layer 13a is provided on the outer side in the tire radial direction of the crown portion of the carcass 11. The belt layer 13a is obtained by rubber-coating a large number of parallel cords. Here, the two belt layers 13a in which the extending directions of the cords intersect form a crossing belt layer. A belt reinforcement layer 15 is disposed outside the belt 13 in the tire radial direction.

  FIG. 2A schematically shows the belt 13 and the belt reinforcing layer 15 of FIG. The belt reinforcing layer 15 is formed by winding a ribbon-shaped rubber strip 15a having a constant width in a spiral shape substantially in the tire circumferential direction. The rubber strip 15a is a single or a plurality of reinforcing cords that are parallel to each other and covered with rubber at regular intervals in the tire width direction. In this example, three reinforcing cords that extend in parallel to each other are tires. A rubber coating is applied at regular intervals in the width direction. The reinforcing cord embedded in the rubber strip 15a can be made of organic fiber, steel, or the like. The width of the rubber strip 15a to be used is preferably 3 to 10 mm from the viewpoints of moldability of the rubber strip 15a and handling at the time of manufacturing the tire. For the same reason, the width of the rubber strip 15a is embedded in one rubber strip 15a. The distance between the reinforcing cords is 0.1 to 3 mm, and the number is preferably 3 to 6.

  When the belt reinforcing layer 15 is divided into one side and the other side in the tire width direction across the tire equatorial plane E, the belt reinforcing layer 15 is wound on one side with a tightly wound portion 17 having a small winding pitch p of the rubber strip 15a and on the other side. A coarsely wound portion 19 having a large pitch p is formed. In the embodiment shown in FIG. 2 (a), the closely wound portion 17 is arranged with the winding pitch p set to be one time the width w of the rubber strip in the tire width direction, and the rubber strip 15a is abutted with no gap therebetween. No. 19 is arranged at intervals so that the winding pitch p of the rubber strip 15a is 1.5 times the width w of the rubber strip in the tire width direction. In the tire 1, the rigidity of the region where the tightly wound portion 17 having a small winding pitch of the rubber strip 15a and a large arrangement density of the reinforcing cords is relatively large, while the winding pitch of the rubber strip 15a is large. The rigidity of the region where the coarsely wound portions 19 where the reinforcing cord arrangement density is small is relatively small.

  When the tire 1 having the above-described configuration is assembled to the regular rim R and filled with the regular internal pressure and attached to the vehicle, the tire width direction one side having the tightly wound portion 17 is positioned inward in the vehicle mounting posture. By attaching, the rigidity in the tire circumferential direction on the inner side of the vehicle mounting of the tire becomes larger than the rigidity in the tire circumferential direction on the outer side of the vehicle mounting.

  By the way, in many passenger vehicles, since the tire is mounted in a so-called negative camber setting in which the posture of the tire when viewed from the front is a C-shape, the tread contact surface of the tire during load rolling The contact length in the tread circumferential direction of the portion is longer on the inner side of the vehicle and shorter on the outer side of the vehicle, and the footprint outline becomes substantially triangular. In the tire 1 according to the present invention, since the rigidity in the tire circumferential direction on the inner side of the tire 1 mounted on the tire is large, the contact length in the tread circumferential direction on the inner side of the vehicle mounting at the time of load rolling is reduced. As a result, road noise and rolling resistance can be reduced, and steering stability during straight travel can be improved. In addition, during braking where the load applied to the vehicle temporarily increases, the contact length in the tread circumferential direction of the vehicle-mounted outer portion of the tire 1 is increased, so that a sufficient contact area can be secured, thereby improving braking performance. To do. Further, even during cornering, if the ground contact pressure of the vehicle-mounted outer portion of the tire 1 is increased, the ground contact length in the tread circumferential direction can be sufficiently increased to obtain a gripping force and improve steering stability. In addition, when designating the mounting direction to the vehicle, a display unit indicating the mounting direction or the rotation direction can be provided on the surface of the tire 1 (not shown).

  Further, since the tire 1 of the present embodiment can change the rigidity in the tire width direction by changing the winding pitch p of the rubber strip 15a, it does not require two or more kinds of rubber strip materials, so that material preparation is possible. In addition, no equipment or time is required for using two or more types of rubber strip materials, and the manufacturing cost and time can be reduced. Two or more kinds of rubber strip materials may be used and wound from the center toward both ends. Further, for example, the rigidity can be changed in the tire width direction very easily compared to the case where the rigidity is changed in the tire width direction by the configuration of the belt layer.

  FIG. 2 (b) shows another embodiment. The winding pitch p of the rubber strip 15 a in the tightly wound portion 17 is 0.8 times the width w of the rubber strip in the tire width direction. The winding pitch p is 1.5 times the width w of the rubber strip in the tire width direction as in the tire of FIG. The winding pitch p between the closely wound portion 17 and the coarsely wound portion 19 is one time the tire width direction width w of the rubber strip, and is disposed so as to face each other. Further, the width in the tire width direction of the closely wound portion 17 and the coarsely wound portion 19 is in a range of 0.15 times the width in the tire width direction from both ends of the belt reinforcing layer 15 in the tire width direction.

  FIG. 2C shows still another embodiment. The winding pitch p of the rubber strip 15a in the tightly wound portion 17 is 0.8 times the width w of the rubber strip in the tire width direction, and the coarsely wound portion 19 is shown. The winding pitch p is 1.5 times the width w of the rubber strip in the tire width direction. The winding pitch p between the closely wound portion 17 and the coarsely wound portion 19 is one time the tire width direction width w of the rubber strip, and is disposed so as to face each other. Further, the width in the tire width direction of the closely wound portion 17 and the coarsely wound portion 19 is in a range of 0.25 times the width in the tire width direction from both ends of the belt reinforcing layer 15 in the tire width direction.

  In the tire 1 of the present invention, the winding pitch p of the rubber strip 15a is rough from the densely wound portion 17 in at least part of the belt reinforcing layer 15 between the closely wound portion 17 and the roughly wound portion 19. It is preferable that it gradually increases in the direction toward the winding portion 19, and according to this, uneven wear occurs when used in a vehicle so as not to cause a large rigidity step in the tire width direction. Can be suppressed. For the same reason, more preferably, the winding pitch p of the rubber strip 15a is gradually increased in the direction from the densely wound portion 17 to the roughly wound portion 19 over the entire area between the densely wound portion 17 and the roughly wound portion 19. It is desirable to become larger.

  Further, when the belt layer 13a constituting the crossing belt layer has the narrowest belt layer in the tire width direction as the narrowest belt layer 13b, the tightly wound portion 17 is at least the narrowest belt layer 13b. It is preferably formed in a tire width direction region from one end in the tire width direction toward the tire equatorial plane E to 1/8 of the width of the narrowest belt layer 13b. In the cross belt layer, the belt cords whose extending directions cross between the plurality of belt layers 13a move in cooperation with each other to increase the reinforcing effect. The belt cord near the end of the narrowest belt layer 13b However, since it is difficult for the belt layers 13a to cooperate with each other, it is difficult to obtain a reinforcing effect. Therefore, as described above, at least from the one end in the tire width direction of the narrowest width belt layer 13b toward the tire equatorial plane E, the tight winding is performed in the tire width direction region up to 1/8 of the width of the narrowest width belt layer 13b. By forming the portion, it is possible to compensate for the lack of rigidity in the vicinity of the end in the width direction of the crossing belt layer, and to more reliably reduce steering stability, road noise, and rolling resistance when traveling straight ahead.

  In the tire 1 of the present invention, it is preferable that the winding pitch p of the rubber strip 15a in the coarsely wound portion 19 is larger than the width w of the rubber strip in the tire width direction. In FIG. 19, since the rubber strips 15a are arranged at intervals in the tire width direction, weight reduction and resource saving can be achieved. More preferably, the winding pitch p of the rubber strip 15a in the rough winding portion is desirably 1.1 to 2 times the width w of the rubber strip in the tire width direction, and if it is less than 1.1 times, it contributes to weight reduction. If the ratio exceeds twice, the effect of suppressing deformation of the tread portion outward in the tire radial direction due to centrifugal force during high-speed running may not be sufficiently obtained.

  Furthermore, in the tire 1 of the present invention, it is preferable that the winding pitch p of the rubber strip 15a in the densely wound portion 17 is equal to or less than the width w of the rubber strip in the tire width direction. By increasing the rigidity in the tire circumferential direction on one side in the width direction, it is possible to reduce steering stability, road noise, and rolling resistance when traveling straight. More preferably, the winding pitch p of the rubber strip 15a in the densely wound portion 17 is preferably 0.5 to 1.0 times the width w of the rubber strip in the tire width direction, and if it is less than 0.5 times, the weight increases. If it exceeds 1.0 times, the rigidity will be lowered, and there is a risk that the steering stability and road noise will decrease.

  While the present invention has been described based on the illustrated examples, the present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the claims. For example, by applying a rubber strip with a large number of reinforcing cords to the tightly wound portion and using a rubber strip with a small number of reinforcing cords in the coarsely wound portion, there is a difference in rigidity between one side and the other side in the tire width direction as required. It is possible to further improve the effect of the present invention. In addition, a belt reinforcement layer can be added for the purpose of supplementing the rigidity in the vicinity of the cross belt layer end, further increasing the rigidity in the tire circumferential direction on the inner side of the vehicle, and further enhancing the effect of the present invention. Can do.

  Next, a pneumatic tire according to the present invention was prototyped, and steering stability (during straight running and cornering), road noise performance, braking performance, and rolling resistance performance were evaluated and will be described below. The pneumatic tires of the examples and comparative examples all have a tire size of 205 / 55R16.

  The tires of Examples 1 to 3 and the comparative example differ only in the structure of the belt reinforcing layer, and the rubber strips constituting the belt reinforcing layer of each tire have a constant width of 6 mm and are parallel to each other at equal intervals. It has three reinforcing cords (PET). Table 1 shows the winding pitch of the rubber strip constituting the belt reinforcing layer of each tire. The value of “winding pitch” in Table 1 indicates how many times the winding pitch is with respect to the width of the rubber strip in the tire width direction (6 mm). When this value is 1, the rubber strip projects without gaps. Indicates that they are arranged together. The “applicable width” is an arrangement range from the both ends in the tire width direction of the rubber strip to which the winding pitch is applied, and the ratio is given by assuming the width (175 mm) of the belt reinforcing layer in the tire width direction as 1. . In each tire, the portion other than the applicable width has a winding pitch of 1, and the tire of the comparative example has a constant winding pitch of 1 over the entire belt reinforcing layer. Further, in the tires of Examples 1 and 3, the width of the narrowest belt layer from the end on one side in the tire width direction of the narrowest belt layer constituting the arranged crossing belt layer toward the tire equatorial plane E is Closely wound portions are formed in the region including the tire width direction region up to 1/8.

(Performance evaluation method)
Steering stability was set on a rim with a size of 6.5 J × 16, mounted on a passenger vehicle with an internal pressure of 220 kPa, and under the load conditions (1.19 to 2.7 kN) for two passengers, the speed ( 60-120 km / h), and obtained by feeling when the vehicle was driven on the outdoor test course.

  In addition, road noise performance is assembled to a rim of size 6.5J × 16, mounted on a passenger vehicle with an internal pressure of 220 kPa, and under a load condition (1.19 to 2.7 kN) for two passengers, the road noise evaluation path Measure the total sound pressure (decibel) with a frequency of 100-500Hz through the sound collecting microphone attached to the center part of the backrest of the driver's seat while driving the test course at 60km / h. Evaluated.

  The brake performance is assembled on a rim of size 6.5J × 16, mounted on a passenger vehicle with an internal pressure of 220 kPa, and the vehicle is placed on a dry road surface under load conditions (1.19 to 2.7 kN) for two passengers. The braking distance until the vehicle becomes stationary when full braking was applied from the initial speed of 100 km / h was evaluated.

  Furthermore, the rolling resistance is a traveling direction generated on the ground contact surface when assembled on a rim of size 6.5J × 16 and rolled at a speed of 80 km / h using an indoor drum tester under a load of 4 kPa with an internal pressure of 220 kPa. The resistance was measured and evaluated.

  The evaluation results are shown in Table 1. Steering stability and road noise are scored according to the feeling of the driver, and the difference in the score is shown using the value of the comparative tire as a control. Brake performance and rolling resistance are indicated by an index with the comparative example tire being set to 100, and the larger the value, the better the performance.

  From the above evaluation results, it can be seen that the tires of Examples 1 to 3 have reduced road noise and rolling resistance, and improved braking performance and steering stability, as compared with the tires of Comparative Examples.

  Thus, according to the present invention, it is possible to provide a pneumatic tire capable of reducing road noise and rolling resistance, improving steering stability when traveling straight, and improving braking performance and steering stability during cornering. became.

1 Pneumatic tire (tire)
3 Tread part 5 Side wall part 7 Bead part 9 Bead core 11 Carcass 13 Belt 15 Belt reinforcing layer 17 Closely wound part 19 Coarsely wound part

Claims (3)

A pneumatic tire having a belt comprising at least one belt layer in which a belt cord is rubber-coated, and a belt reinforcing layer provided on the outer side in the tire radial direction of the belt,
The belt reinforcing layer is made of rubber strip having a constant width extending helically in the tire circumferential direction, and has a close coiled portion in the region of the tire on one widthwise side to be classified by the tire equatorial plane, the tire width In the region on the other side of the direction, there is a rough winding part,
Winding pitch of the rubber strip in the close coiled portion, Ri Oh small than winding pitch of the rubber strip in the coarse winding portion,
The width in the tire width direction of the rubber strip in the densely wound portion and the roughly wound portion is constant in a range of 3 mm to 10 mm,
In the rubber strip, 3 to 6 reinforcing cords are arranged at regular intervals of 0.1 mm to 3 mm in the tire width direction,
The winding pitch of the rubber strip in the rough winding portion is 1.1 to 2 times the width of the rubber strip in the tire width direction,
A pneumatic tire characterized in that a winding pitch of the rubber strip in the tightly wound portion is 0.5 times or more and less than 1.0 times the width of the rubber strip in the tire width direction .   The winding pitch of the rubber strip gradually increases in a direction from the densely wound portion toward the coarsely wound portion at least at a part between the densely wound portion and the roughly wound portion in the belt reinforcing layer. Item 2. The pneumatic tire according to Item 1. The belt constitutes an intersecting belt layer composed of at least two belt layers in which the extending direction of the belt cord intersects each other, and the belt layer having the narrowest width in the tire width direction is the narrowest width among the intersecting belt layers. When it is a belt layer,
The tightly wound portion is at least a region in the tire width direction up to 1/8 of the width in the tire width direction of the narrowest belt layer from one end in the tire width direction of the narrowest belt layer toward the tire equatorial plane. The pneumatic tire according to claim 1, wherein the pneumatic tire is formed as described above.

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