JP5961936B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, which is a pneumatic tire adopting a pitch variation in which the size of each block is changed in the tire circumferential direction, and has a small variation in cornering power and an improved responsiveness. About.

  Conventionally, in a pneumatic tire, the pitch variation mentioned above is employ | adopted and the block is comprised in order to suppress pattern noise.

  However, because the block size is different between the small pitch and the large pitch, the cornering power on the tire circumference changes, and it becomes responsive by the input timing at the time of steering (input through the block rigidity on the ground surface). There was a slight difference.

  It is said that the change in axle force or the like generated due to such a rigid discontinuity in the tread portion is canceled by forming a rigid change portion in the side portion of the tire corresponding to the discontinuous portion of the tread. There is a proposal (Patent Document 1).

  However, the formation of the part where the stiffness changes in the side part of the tire as in this proposal is a very heavy load on the side part when the tire rolls. It is difficult to adopt it.

JP 2003-237317 A

  In view of the above-described points, the object of the present invention is that the cornering power fluctuation is small and the responsiveness is improved regardless of adopting a pitch variation in which the size of each block is changed in the tire circumferential direction. It is to provide a pneumatic tire.

Above object can be achieved by a pneumatic tire of the following (1).
(1) A pneumatic tire having two or more circumferential grooves has a tread pattern in which the pitch arrangement is different between the center block and the shoulder block and the contact width changes on the tire circumference. The shorter the pitch length of the center block, the greater the ground contact width by positioning the virtual intersection of the tread arc line and the sidewall arc line at the pitch outside the tire width direction. A pneumatic tire characterized in that the length ratio between the maximum contact width and the minimum contact width is 1.03 to 1.06.

Further, in the pneumatic tire of the present invention of (1), it is more preferable to have the following configuration (2) .
(2) The pneumatic tire according to (1) , wherein a random arrangement is adopted as a pitch arrangement of at least one block of the shoulder portion or the center portion.

According to the pneumatic tire of the present invention according to claim 1 , although the pitch variation in which the size of each block is changed in the tire circumferential direction is adopted, the fluctuation of the cornering power is small and the responsiveness is improved. A pneumatic tire is provided.

  If this pneumatic tire is used, the pattern noise is suppressed because the pitch variation is adopted, and even though the pitch variation is adopted, the fluctuation of the cornering power is extremely small and the response at the time of steering is constant. The level is improved, and good steering performance and favorable steering feeling are brought about.

The pneumatic tire according to claim 1 can be applied to a pneumatic tire having a tread pattern in which a pitch arrangement is different between a center block and a shoulder block .

According to the pneumatic tire of the present invention concerning claim 2 , while having the effect of the pneumatic tire of claim 1 , the effect of the present invention can be obtained more clearly.

It is the figure which showed the tread pattern used as a reference example when demonstrating the pneumatic tire of this invention . It is the figure which showed the tread pattern explaining the pneumatic tire of this invention concerning Claim 1 . As an example of a pitch variation tire that realizes the pneumatic tire of the present invention, the pitch length on the tire circumference is divided into three types (pitch: large, medium, small), corresponding to each pitch. Thus, a tire showing an example in which a tire tread pattern is formed by changing the positions of virtual intersections P (P1, P2, P3) of the arc line L1 of the tread 1 and the arc line L2 of the sidewall 6 of the pneumatic tire. It is a profile figure near a shoulder part.

  Hereinafter, the pneumatic tire of the present invention will be described in more detail.

As shown in FIG. 1, a pneumatic tire serving as a reference example for explaining the pneumatic tire of the present invention has a tread pattern in which the tread portion 1 has a contact width varying on the tire circumference. The shorter the pitch length of the block 3 of the shoulder portion, the larger the ground contact width at that pitch. In the figure, 2 is a tire equator and 5 is a circumferential groove.

As shown in FIG. 2, the pneumatic tire according to the first aspect of the present invention is a pneumatic tire having two or more circumferential grooves 5, and the tread portion 1 has a contact width that varies on the tire circumference. The tread pattern 1 is provided, and the shorter the pitch length of the block 4 in the center portion, the larger the ground contact width at that pitch.

In the pneumatic tire of the present invention, the tread pattern is configured so that the ground contact width at the pitch of the block becomes larger as the pitch length is shorter at the center portion, and the ground contact width is increased as the pitch is smaller to increase the ground contact area. Thus, the tread rigidity is ensured, thereby improving the responsiveness.

The present invention can be applied to a pneumatic tire having a tread pattern in which the pitch arrangement is different between the center block and the shoulder block.

In the present invention, the length ratio of the maximum ground contact width and the minimum ground width on circumference it is necessary to satisfy the 1.03 to 1.06. If there is too much difference between the maximum ground contact width and the minimum ground contact width on this circumference, there is a concern that vibration will occur. Therefore, according to various findings by the present inventors, the upper limit is 1. and up to 06, the lower limit was set to 1.03, there is a tendency that the effect of the present invention is less than 1.03 reduced. That is, if there is a significant difference between the maximum and minimum ground contact widths, there is a concern about the occurrence of vibrations. Therefore, it is preferable to set an upper limit on the difference. For reference, on the tire profile of the meridian cross section, the variation in the height of the shoulder portion is around 1 mm because the length ratio of the maximum contact width and the minimum contact width is approximately 1.06 times, and the length ratio is Up to 1.06 . When the length ratio between the maximum contact width and the minimum contact width on the circumference is 1.03 to 1.06, a specific example will be described. For example, in a tire of 185 / 60R15 size, Since the tire ground contact width is 126 mm, assuming that the minimum ground contact width is 126 mm, for example, the maximum ground contact width in which the length ratio is 1.03 to 1.06 is 130 to 134 mm.

  Moreover, it is preferable to employ a random arrangement for the arrangement of the pitch of at least one block of the shoulder portion or the center portion. Here, “random arrangement” means a portion in which the pitch length change in a place where the adjacent pitch lengths are different changes not in one step but in two or more steps when the pitch length is divided into several types on the tire circumference. Means that there is at least one pitch arrangement on the circumference, and the pitch length change in a place where adjacent pitch lengths are different is a concept contrary to “periodic arrangement” which is one step everywhere on the circumference. . In the case of periodic arrangement, small pitch continuation and large pitch continuation occur, so it is not suitable for the purpose of further improving responsiveness, but if random arrangement is adopted and the ground contact width is also changed, Since the effect of a more responsive improvement is acquired, it is preferable.

  In the present invention, the “contact width” refers to a camber angle and a toe angle of 0% when a tire is mounted on a standard rim defined by JATMA, filled with air pressure of 180 kPa, and a load of 70% of the maximum load capacity is applied. When the tire is rolled at 2 km / h on a smooth plane in the state of 0 °, it means the contact width of each pitch at the portion where the tire touches the plane.

  There are various methods for producing the pneumatic tire of the present invention. For example, the method of tread pattern design, such as changing the dimensions of the block in the tire width direction for each block where the contact width has changed on the tire circumference, or changing the contact width on the tire circumference by changing the tread rubber hardness The pneumatic tire of the present invention can be constituted by a method by designing a rubber material such as changing for each block, a plurality of combinations of these methods, or the like.

  Among them, a method that can be realized relatively easily and reliably is a method in which the dimension of the block in the tire width direction is changed for each block in which the contact width changes on the tire circumference, and this concept is illustrated in FIG. , (B), (c).

  In FIG. 3, when the pitch length on the tire circumference is divided into three types (pitch: large, medium, small), the pneumatic tires corresponding to each pitch (large, medium, small) In the vicinity of the shoulder portion of the example in which the tire tread pattern is formed by changing the position of the virtual intersection P (P1, P2, P3) of the arc line L1 of the tread 1 and the arc line L2 of the sidewall 6 (in the width direction). A profile diagram is shown. Reference numeral 2 denotes a tire equator, (a) shows a case where the pitch is small, (b) shows a case where the pitch is medium, and (c) shows a case where the pitch is large. , P2 and P3 are located on the outer side in the tire width direction (positions further away from the tire equator) in that order. The virtual intersections P1, P2, and P3 do not directly indicate the tire ground contact width, but their positions generally correspond to the large to medium to small tire ground contact widths. Therefore, when manufacturing a tire according to the present invention, The positions of the virtual intersections P1, P2, and P3 are preferably set as appropriate.

Examples 1-3 , Reference Examples 1-2, Conventional Example 1
Evaluation of responsiveness was done by mounting a test tire with a tire size of 185 / 60R15 on a rim with a rim size of 15 × 6J, attaching it to an FF passenger car with an air pressure of 220 kPa and a displacement of 1500 cc, running on a dry road surface test course, and a test driver. The sensory evaluation was performed, and the evaluation score was indexed with the conventional example as the reference value 100. The larger the value, the better the response.

  In the vibration evaluation, the vertical run-out with the same rim and air pressure as in the above-mentioned actual vehicle evaluation with a camber angle of 2 degrees and a uniformity of 80 km / h was indexed as a reference value of 100 as a conventional example. The larger the value, the smaller the vibration. The index up to 98 is a satisfactory level.

The details of the test tires and the evaluation results are shown in Table 1. According to the present invention (Examples 1 to 3 and Reference Examples 1 to 2 ), the pattern shown in FIGS. 1 and 2 is applied. In the conventional example, there is no variation in the contact width with respect to the circumference.

  As can be seen from Table 1, by using the pneumatic tire of the present invention, the responsiveness can be improved without generating new problems such as large vibrations despite the adoption of pitch variations. Is possible.

1: Tread portion 2: Tire equator 3: Shoulder block 4: Center block 5: Circumferential groove 6: Side wall P (P1, P2, P3): Tread arc line L1 and side wall arc line L2 virtual intersection L1: Arc line of tread 1 L2: Arc line of sidewall 6

Claims (2)

A pneumatic tire having two or more circumferential grooves has a tread pattern in which the pitch arrangement is different between the center block and the shoulder block, and the contact width varies on the tire circumference, and the center portion The shorter the pitch length of the block, the larger the ground contact width by placing the virtual intersection of the tread arc line and the sidewall arc line at that pitch outside the tire width direction, and the maximum ground contact on the tire circumference A pneumatic tire characterized in that the length ratio between the width and the minimum contact width is 1.03 to 1.06. The pneumatic tire according to claim 1 , wherein a random arrangement is adopted as a pitch arrangement of at least one block of the shoulder portion or the center portion.

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