JP5563225B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire used for a passenger car and the like, and more particularly to a pneumatic tire that improves rolling resistance.

  Conventionally, a pneumatic tire is known in which a belt reinforcing layer in which an organic fiber cord such as a nylon cord is spirally wound at an angle close to 0 degrees in the tire circumferential direction is arranged on the outer peripheral side of the belt layer. By providing such a belt reinforcing layer, it is known that the end of the belt layer due to centrifugal force during high-speed running can be suppressed and high-speed durability can be improved (for example, see Patent Document 1).

  By the way, in recent years, there has been a strong demand for improvement in fuel consumption of vehicles due to problems such as environment and fuel cost. Therefore, there is a strong demand for countermeasures for pneumatic tires, that is, improvement of rolling resistance that greatly affects fuel consumption.

JP-A-6-24208

  The objective of this invention is providing the pneumatic tire which can improve rolling resistance in the pneumatic tire which has a belt reinforcement layer.

Air pneumatic tire of the present invention, the carcass layer was extended between the right and left bead portions, a belt layer of two layers arranged on the carcass layer outer peripheral side of the tread portion, the outer periphery of the belt layer across the belt layer An organic fiber cord selected from nylon cords, vinylon cords, polyester cords, polyolefin ketone cords having a tensile strength of 50N to 350N and an elastic modulus of 1 to 20 GPa. In a pneumatic tire provided with a belt reinforcing layer wound in a spiral shape, a rubber strip with a cord of 2 to 10 mm in width embedded in the organic fiber cord is spirally wound in the tire circumferential direction while being fed in the tire axial direction. A belt reinforcing layer is formed by turning the belt, and the belt reinforcing layer is wider on the left and right sides of the tire equatorial plane. A first belt reinforcing portion disposed in a region Z1 between positions separated by 0.1 to 0.4 times the width W of the layer, and second belt reinforcing portions disposed on both sides of the first belt reinforcing portion, By making the feed pitch width of the corded rubber strip of the first belt reinforcing portion 0.4 to 0.6 times the feed pitch width of the corded rubber strip of the second belt reinforcing portion, the first belt reinforcement The winding density of the organic fiber cord of the second belt reinforcing portion is made higher than the winding density of the organic fiber cord of the second belt reinforcing portion, and the initial strain of the organic fiber cord of the first belt reinforcing portion is wide on the left and right sides from the tire equatorial plane. In the region between the positions separated by at least 0.1 times the width W of the other belt layer, −1.5 to 1.5% is used.

According to the air-containing tire according to the present invention described above, higher than the upper Symbol first -1.5～1.5% initial strain of the organic fiber cords of the belt reinforcing portion of the conventional, which is placed in the region Z1 and As a result, it is possible to effectively suppress the rise of the center portion of the tread portion that greatly affects the rolling resistance, so that the rolling resistance can be reduced and the rolling resistance can be improved.

As a result , the rolling resistance can be further improved by the belt reinforcing layer in the tire in which the belt reinforcing layer suppresses the rising of the belt layer end due to the centrifugal force during high-speed running and the high-speed durability is improved.

1 is a tire meridian cross-sectional view showing a reference tire that is the basis of a pneumatic tire of the present invention. Is a tire meridian cross-sectional view showing an implementation form of the pneumatic tire of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows one embodiment of a reference tire that is the basis of the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion.

  A carcass layer 4 is embedded in which reinforcing cords extending in the tire radial direction between the left and right bead portions 3 are arranged at predetermined intervals in the tire circumferential direction and embedded in the rubber layer, and both end portions thereof are embedded in the bead portion 3. The bead filler 6 is folded back from the inner side in the tire axial direction so as to sandwich the bead filler 6 around the bead core 5.

  Provided on the outer peripheral side of the carcass layer 4 of the tread portion 1 is a two-layer belt layer 7 in which reinforcing cords arranged so as to be inclined in the tire circumferential direction are arranged so as to intersect with the inclination direction with respect to the tire circumferential direction being reversed. It has been. The two belt layers 7 are composed of a first belt layer 7X arranged on the inner peripheral side and a second belt layer 7Y arranged on the outer peripheral side of the first belt layer 7X, and the width W of the first belt layer 7X is It is wider than the width of the second belt layer 7Y.

On the outer peripheral side of the two belt layers 7, an organic fiber cord having a strength at the time of cutting in a tensile test of 50 to 350 N and an elastic modulus of 1 to 20 GPa is an angle close to 0 degrees in the tire circumferential direction (5 1 layer or less) is provided with a single belt reinforcing layer 8 wound spirally continuously in the tire circumferential direction. The tensile strength and elastic modulus referred to here are values measured according to the measuring method described in JIS L1017.

Such tension and organic fiber cord having a strength and modulus at break of the test, nylon cord, vinylon codes, polyester codes, a polyolefin ketone code used. Belt reinforcing layer 8, in the near one cord containing rubber strip width 2~10mm with embedded organic fiber cords at 0 ° to the tire circumferential direction while feeding in the tire axial direction angle (5 degrees or less) as this continuously that make up by winding spirally.

In this reference tire, the belt reinforcing layer 8 is 0.1 to 0.4 times the width W of the wider first belt layer 7X on the left and right sides along the tire axial direction from the tire equatorial plane TE. It is arranged only in the region Z1 between the distant positions, and the initial strain of the organic fiber cord is in the range of -1.5 to 1.5%. The region in which the initial strain is in the range of -1.5 to 1.5% may be the entire region Z1, but from the viewpoint of the effect, the regions on the left and right sides along the tire axial direction from the tire equatorial plane TE are respectively. What is necessary is just to make it the range of -1.5-1.5% in the area | region Z2 between the positions at least 0.1 times the width W of 1 belt layer 7X.

  The initial strain of the organic fiber cord referred to in the present invention is the initial strain is ε (%), the cord length in the tire is L0 (mm), and the cord length when taken out from the tire (belt reinforcing layer). Assuming that L1 (mm), ε = 100 (L0−L1) / L0. At the time of measurement, the measurement target is set to 300 mm (that is, L0 = 300 mm), and the initial strain is determined.

  As a result of intensive investigations on the improvement of rolling resistance and repeated experiments, the present inventors have found the following. That is, the rolling resistance is speed dependent, and the rolling resistance increases as the speed increases. On the other hand, as the speed increases, the tread portion of the tire rises outward in the tire radial direction due to centrifugal force. Therefore, attention was paid to the cross-sectional shape of the tread portion (tread surface) where the rising occurs.

  Examining the cross-sectional shape of the tread, the cross-sectional shape is different between the contact area and the non-contact area, and the higher the speed, the greater the difference in cross-sectional shape between the contact area and the non-contact area, and the resulting energy loss increases. . As a result, the rolling resistance increased, and it was found that the difference in cross-sectional shape between the contact area and the non-contact area greatly affects the rolling resistance.

  Therefore, reducing the difference in cross-sectional shape between the contact area and the non-contact area is important for reducing rolling resistance. However, in a pneumatic tire in which two belt layers are arranged, the center is usually more central than the shoulder of the tread. The part rises greatly outward in the radial direction of the tire by centrifugal force in a non-contact area. Therefore, if the rising at the center portion can be suppressed, the difference in cross-sectional shape between the contact area and the non-contact area can be effectively reduced, and the rolling resistance can be reduced. Therefore, in the present invention, the belt reinforcement layer 8 is disposed in the above-described region Z1, while the initial strain of the organic fiber cord is defined as described above.

  When the region Z1 is narrower than 0.1 times the width W, the effect of suppressing the rise of the center portion of the tread portion 1 becomes insufficient, and it becomes difficult to reduce the rolling resistance. On the other hand, if it exceeds 0.4 times, the rise at the shoulder portion is also suppressed. As a result, the rise difference between the center portion and the shoulder portion is reduced, and the rolling resistance is adversely affected.

  When the initial strain of the organic fiber cord of the belt reinforcing layer 8 is less than −1.5%, the effect of suppressing the rise of the center portion of the tread portion 1 becomes insufficient, and it becomes difficult to improve the rolling resistance. Since the pneumatic tire is manufactured through a vulcanization process, the organic fiber cord of the belt reinforcing layer usually remains strained after vulcanization. The cord with a large initial strain has a small twisting action, and by utilizing the stiffness of the cord, the rigidity of the belt reinforcing layer can be increased and the tagging effect can be exhibited. However, if the initial strain is too large, the tagging effect becomes too great and the cross-sectional shape is distorted, which adversely affects the rolling resistance. Therefore, the upper limit of the initial strain of the organic fiber cord of the belt reinforcing layer 8 is set to 1.5%.

  In the pneumatic tire in which the initial strain of the organic fiber cord of the belt reinforcing layer 8 is as described above, the diameter of the tread surface corresponds to the diameter of the inner surface of the tire mold when the green tire is set in the tire mold. Form a green tire so that it is about 0.5 to 1.5% smaller (form the green tire tread surface to a diameter closer to the inner surface of the tire mold) and place it inside the tire mold It can be obtained by inflating from the inside with a bladder and vulcanizing.

In the above reference tire , preferably, the belt reinforcing layer 8 is disposed between positions separated from the tire equatorial plane TE by 0.15 to 0.3 times the width W of the first belt layer 7X on the left and right sides along the tire axial direction. Arranging only in the region may be more effective. In other words, the region Z1 is located between the tire equatorial plane TE and a position 0.15 to 0.3 times the width W of the first belt layer 7X on the left and right sides along the tire axial direction. Also in this case, the region where the initial strain of the organic fiber cord of the belt reinforcing layer 8 is in the range of -1.5 to 1.5% may be the entire region Z1, but from the point of effect, the tire equator plane What is necessary is just to make it the range of -1.5 to 1.5% in the area | region between the position which separated at least 0.15 times the width W of the 1st belt layer 7X on both the left and right sides along a tire axial direction from TE.

Figure 2 shows the real施形condition of the pneumatic tire of the present invention. In this pneumatic tire, the belt reinforcing layer 8 is disposed so as to cover the entire belt layer 7, and the first belt layer having a wider width on each of the left and right sides along the tire axial direction from the tire equatorial plane TE. A first belt reinforcing portion 9 disposed in a region Z1 between positions spaced 0.1 to 0.4 times the width W of 7X, and a second belt reinforcing portion 10 disposed on both sides of the first belt reinforcing portion 9 It is composed of

  The winding density of the organic fiber cord of the first belt reinforcing portion 9 (the number of windings per unit width) is higher than the winding density of the organic fiber cord of the second belt reinforcing portion 10. For example, the first belt reinforcing portion 9 can have a two-layer structure and the second belt reinforcing portion 10 can have a one-layer structure.

  The initial strain of the organic fiber cord of the first belt reinforcing portion 9 is in the range of -1.5 to 1.5%. The region where the initial strain is in the range of -1.5 to 1.5% may be the entire region Z1 as described above, but from the point of effect, the region from the tire equatorial plane TE to the left and right along the tire axial direction. What is necessary is just to make it the range of -1.5-1.5% in the area | region Z2 between the positions which are separated at least 0.1 times the width W of the 1st belt layer 7X on both sides, respectively. Other configurations are the same as those of the embodiment of FIG. 1, and the same reference numerals are given to the same components, and description thereof is omitted.

  In the embodiment of FIG. 2, the belt reinforcing layer 8 suppresses the rising of the end of the belt layer 7 due to the centrifugal force during high-speed running and improves high-speed durability, while at the center portion of the tread portion 1. In a pneumatic tire with a belt reinforcement layer that can suppress rolling and reduce rolling resistance and improve conventional high speed durability, the belt reinforcement layer further improves rolling resistance. It is.

The belt reinforcing layer 8 of the embodiment of FIG. 2 also has an angle close to 0 degrees in the tire circumferential direction (5 degrees or less) while feeding one cord-containing rubber strip having a width of 2 to 10 mm embedded with organic fiber cords in the tire axial direction. ) in is constitutively by winding a continuously spiral, in which case the feed pitch of the cords rubber strip of the first belt reinforcing portion 9 (the feed length of the time of winding) of the second belt reinforcing The winding density of the organic fiber cord of the first belt reinforcing portion 9 is increased so as to be 0.4 to 0.6 times the feed pitch width (feed length during winding) of the rubber strip containing the cord of the portion 10. you. Normally, the second belt reinforcing portion 10 is wound so that the corded rubber strips are in contact with each other. For example, if the rubber strip with a cord of 10 mm is used, the corded rubber in the second belt reinforcing portion 10 is used. The feed pitch width of the strip is 10 mm, and the feed pitch width of the corded rubber strip in the first belt reinforcing portion 9 is 4 to 6 mm.

  When the feeding pitch width of the corded rubber strip of the first belt reinforcing portion 9 exceeds 0.6 times, the effect of suppressing the rise of the center portion of the tread portion 1 becomes insufficient, and it becomes difficult to improve the rolling resistance. . On the other hand, if it is less than 0.4 times, the hoop effect becomes too great, the cross-sectional shape is distorted, and the rolling resistance is adversely affected.

  The feeding pitch width of the corded rubber strip is constant in each of the first belt reinforcing portion 9 and the second belt reinforcing portion 10, but may be variable. When making it variable, it is made the smallest in a region Z2 between the positions separated by 0.1 times the width W of the first belt layer 7X on the left and right sides along the tire axial direction from the tire equatorial plane TE. Increasing the width gradually toward the outside in the width direction is preferable from the viewpoint of suppressing uneven wear.

  Similarly to the above, the region Z1 where the first belt reinforcing portion 9 is located is 0.15 to 0.3 times the width W of the first belt layer 7X on the left and right sides along the tire axial direction from the tire equatorial plane TE. It is preferable to locate between the distant positions in order to enhance the effect. Also in this case, the region where the initial strain of the organic fiber cord of the first belt reinforcing portion 9 is in the range of -1.5 to 1.5% may be the entire region Z1, but from the point of effect, the tire What is necessary is just to make it the range of -1.5-1.5% in the area | region between the positions at least 0.15 times the width | variety W of the 1st belt layer 7X on the left-right both sides along the tire axial direction from the equatorial plane TE. .

  Although this invention can be preferably used especially for the pneumatic tire for passenger cars, it is not limited to it.

Table 1 shows the region Z1 where the tire size is common to 195 / 65R15 and the belt reinforcement layer is arranged (the total of the left and right of the equatorial plane is displayed) and the initial strain of the organic fiber cord of the belt reinforcement layer (measured in the region Z2) reference tires and comparative tires 1 to 4 having the structure of FIG. 1 which is adapted, the first belt reinforcing portion of the region Z1 (Show all) and measured at an initial strain (area Z2 of the organic fiber cords of the first belt reinforcing portion ) the present invention tire having the structure of FIG. 2 as shown in Table 1, and other no belt reinforcing layer to prepare a reference tire having the same structure as that of reference tire as respective test tires.

In each test tire, a steel cord was used as the reinforcing cord for the belt layer, and a nylon cord ( strength at the time of cutting in the tensile test of 150 N, elastic modulus 2.1 GPa) was used as the organic fiber cord of the belt reinforcing layer. Further, a corded rubber strip having a width of 10 mm is used for the belt reinforcing layer of each test tire. In the tire 6 of the present invention, the feeding pitch width of the corded rubber strip of the first belt reinforcing portion is set to the cord of the second belt reinforcing portion. The feed pitch width of the rubber strip was 0.5 times.

  Each of these test tires was mounted on a rim having a rim size of 15 × 6 JJ, and a rolling resistance evaluation test was performed by the following method. The results shown in Table 1 were obtained.

Rolling resistance Each test tire was attached to a drum-type tire rolling resistance tester with an air pressure of 200 kPa, and the rolling resistance when running under conditions of a load of 4.5 kN and a speed of 80 km / h was measured. The evaluation result is indicated by an index value where the reference tire is 100. It means that rolling resistance is so low that this value is small.

  Table 1 shows that the tire of the present invention can improve rolling resistance.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 7 Belt layer 8 Belt reinforcement layer 9 1st belt reinforcement part 10 2nd belt reinforcement part TE Tire equatorial plane W width Z1, Z2 area | region

Claims (3)

A carcass layer is extended between the left and right bead parts, two belt layers are arranged on the outer periphery side of the carcass layer in the tread part, and the belt layer is covered on the outer periphery side of the belt layer by cutting in a tensile test. Belt reinforcement with organic fiber cords selected from nylon cords, vinylon cords, polyester cords, and polyolefin ketone cords having a strength of 50 N to 350 N and an elastic modulus of 1 to 20 GPa spirally wound in the tire circumferential direction In pneumatic tires with layers,
A belt reinforcing layer is formed by spirally winding a rubber strip with a cord of 2 to 10 mm in width embedded in the organic fiber cord in the tire circumferential direction while feeding in the tire axial direction, and the belt reinforcing layer is formed from the tire equatorial plane. A first belt reinforcing portion disposed in a region Z1 between positions 0.1 to 0.4 times wider than the width W of the wider belt layer of the two belt layers on each of the left and right sides; A belt reinforcing portion disposed on both sides of the belt reinforcing portion, and a feeding pitch width of the corded rubber strip of the first belt reinforcing portion is set to a feeding pitch width of the corded rubber strip of the second belt reinforcing portion. by the 0.4 to 0.6-fold, the winding density of the organic fiber cord of the first belt reinforcing portion higher than the winding density of the organic fiber cord of the second belt reinforcing portion, and the first Organic fiber for belt reinforcement A pneumatic tire in which the initial strain of the cord is -1.5 to 1.5% in a region between positions at least 0.1 times the width W of the wider belt layer on the left and right sides from the tire equatorial plane. The feed pitch of the cords rubber strip, and the smallest in the region between 0.1 times away position of the width W of each wider belt layer to the left and right sides from the tire equatorial plane, the tire width direction outside from the region The pneumatic tire according to claim 1 , which is gradually increased toward the front. The region Z1 is positioned between 0.15 to 0.3 times the width W of the wider belt layer on the left and right sides from the tire equatorial plane, and the initial strain of the organic fiber cord of the first belt reinforcing portion is the tire The pneumatic tire according to claim 1 or 2 , which is -1.5 to 1.5% in a region between positions separated at least 0.15 times the width W of the wider belt layer on both the left and right sides from the equator plane. .

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