JP2010052502A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of simply and precisely determining a tire exchanging timing based on a change in dispersion of the frequency of a pattern noise generated by a tire. <P>SOLUTION: In this pneumatic tire, design elements including a combination of a plurality of pitches with different pitch lengths in a tire circumferential direction Y are aligned on a tread face 1. In this tire, the design elements arranged in a central area R1 contacted until tread friction reaches to 50-80% of a friction limit are made different from design elements arranged in shoulder areas R2, R2 contacted until the tread friction reaches to 100% of at least the friction limit on both sides. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can easily and accurately determine the replacement time of a tire based on a change in frequency dispersion of pattern noise generated by the tire.

  Conventionally, as a method for recognizing the wear level of a pneumatic tire, it has been widely performed to determine the tire replacement time by checking the depth of the remaining groove of the tire by visual observation or actual measurement. However, this method is reliable, but it is very complicated because it is necessary to perform direct confirmation work over many times, and moreover, since the confirmation work is left exclusively to the driver, the exact replacement time is determined. It had drawbacks such as being extremely difficult to do.

As a countermeasure, grooves with different depths are formed on the tire tread surface, and the frequency of the vehicle changes as the surface area of the land section defined by these grooves changes with the progress of wear. There is a proposal (see, for example, Patent Document 1) in which the wear state is estimated by reading the change in frequency. However, these proposals require a special device for estimating the wear situation, and it is necessary to install these devices in each vehicle. There was a problem that it was difficult to adopt the depth recognition method.
JP 2005-186702 A

  An object of the present invention is to solve such a conventional problem, and to provide a pneumatic tire in which a tire replacement time can be easily and accurately determined by a change in frequency dispersion of pattern noise generated by the tire. There is.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire in which design elements composed of a combination of a plurality of pitches having different pitch lengths in the tire circumferential direction are arranged on the tread surface. Is different between a center region that contacts 50 to 80% of the wear limit and a shoulder region that contacts at least 100% of the wear limit on both sides of the center region, thereby generating a design element for the center region. The frequency dispersion of the pattern noise and the frequency dispersion of the pattern noise generated by the design element of the shoulder region are different.

In the above-described configuration, it is preferable that the sound pressure level of the pattern noise generated by the design element in the shoulder region is higher than the sound pressure level of the pattern noise generated by the design element in the central region. In this case, it is preferable to configure as described in (1) to (5) below.
(1) The number of types of pitch length in the shoulder region is made smaller than the number of types of pitch length in the central region.
(2) The ratio between the maximum pitch length and the minimum pitch length in the shoulder region is made smaller than the ratio between the maximum pitch length and the minimum pitch length in the central region.
(3) The total pitch number in the shoulder region is 1.25 times or more the total pitch number in the central region.
(4) In the shoulder region, two types of pitches having a pitch length ratio of 1.1 to 2.0 are alternately arranged in a cycle of 1 to 4 in the tire circumferential direction.
(5) The pitch arrangement in the shoulder region is constituted by a block row partitioned into lug grooves extending in the tire width direction. In this case, the angle of the lug groove with respect to the tire circumferential direction may be 60 ° or more.

  According to the present invention, in a pneumatic tire in which design elements each having a combination of a plurality of pitches having different pitch lengths in the tire circumferential direction are arranged on the tread surface, the tread wear is reduced to 50 to 80% of the wear limit. The frequency distribution of the pattern noise generated by the design element in the central area and the design element of the shoulder area are made different between the central area that contacts the ground area and the shoulder area that contacts at least 100% of the wear limit on both sides of the central area. Since the pattern noise generated from the tire changes when the wear progresses and the shoulder area touches down, the pattern noise generated from the pattern noise is different from the frequency dispersion of the pattern noise generated. The driver can easily and accurately determine when to change tires. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a partial plan view showing an example of a tread surface of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is a half sectional view showing a structure of a tread portion of the tire of FIG.

  On the tread surface 1 of the pneumatic tire of the present invention, design elements composed of a combination of a plurality of pitches having different pitch lengths with respect to the tire circumferential direction Y are arranged, and thereby frequency dispersion of pattern noise is performed. Yes. And in the pneumatic tire of this invention, as shown in FIG.1 and FIG.2, the design element arrange | positioned in the center area | region R1 to which a tread wear reaches 50 to 80% of a wear limit, and at least in this both sides The frequency dispersion of the pattern noise generated by the design elements in the central region R1 is made different from the design elements arranged in the shoulder regions R2 and R2, which are grounded until reaching the wear limit of 100% (in the figure, 100% of the wear limit). And the frequency dispersion of the pattern noise generated by the design elements of the shoulder regions R2 and R2.

  That is, in the embodiment of FIG. 1, the design elements in the central region R1 are configured by six block rows in which substantially parallelogram-shaped blocks 2 are arranged in the tire circumferential direction Y, and the design elements in the shoulder regions R2 and R2 are respectively A substantially rectangular block 3 is constituted by one block row arranged in the tire circumferential direction Y. In the figure, CL indicates a tire equator line.

  As a result, when the wear progresses and the shoulder regions R2 and R2 come in contact with the ground, the pattern noise generated from the tire changes to notify that the wear limit has been approached. And it can be determined accurately.

In FIG. 2, dotted lines P and Q displayed on the tread portion 4 respectively indicate the time when the tread wear reaches 50 to 80% of the wear limit and the time when the wear limit reaches 100% as the wear progresses. The imaginary line of the tread surface 1 is shown, and the outer end of the grounding region at each time point is indicated by X1 and X2. In the figure, S indicates an envelope connecting the groove bottoms of the main grooves 5 formed in the tread portion 4 to each other.

  In the embodiment shown in FIG. 1, the blocks 3 and 3 in the shoulder regions R2 and R2 extend outward in the tire width direction beyond the shoulder regions R2 and R2, respectively. There are cases in which they are arranged in the regions R2 and R2.

  The virtual line Q of the tread surface 1 when the wear limit reaches 100% is the position of the tread surface 1 when the remaining groove depth in the main groove 5 formed on the tread surface 1 is 1.6 mm. Is shown. Therefore, in the pneumatic tire of the present invention, the wear limit is set based on the depth of the main groove 5, and when the depth of the main groove 5 formed in the tread surface 1 is different, the depth is The smallest main groove 5 is set as a reference.

  In the present invention, the above-described central region R1 is a region that contacts the ground until reaching the wear limit of 50 to 80%, depending on the type and size of the tire, and the timing for notifying that the wear limit has been approached. In the case of a general pneumatic tire for a passenger car, the central region R1 is set to be a region that contacts 50 to 60% of the wear limit, and preferably reaches 50% of the wear limit. it can.

  In the present invention, when the design element in the central region R1 and the design element in the shoulder region R2 are different from each other, the pattern in which the design element in the shoulder region R2 is generated and the sound pressure level of the noise is the pattern in which the design element in the central region R1 is generated. It may be set to be larger than the sound pressure level of noise. This makes it easier for the auditory to recognize the change in pattern noise when the shoulder region R2 comes into contact with the ground, so that the driver can be surely recognized that the wear limit is approaching.

  The pneumatic tire of the present invention set as described above exhibits noise characteristics as shown in FIGS. 3A and 3B as the wear progresses. That is, noise characteristics as shown in FIG. 3 (a) are shown in the initial stage of wear up to 50 to 80% of the wear limit, and in the last stage of wear where the wear has advanced from this, it is shown in FIG. 3 (b). As described above, the frequency range of the noise generated from the central region R1 and the frequency range of the noise generated from the shoulder region R2 are shifted from each other, and the sound pressure level of the noise generated from the shoulder region R2 is the central region R1. The noise characteristic which became larger than the sound pressure level of the noise which generate | occur | produces from is shown.

  In adjusting the design element of the central region R1 and the design element of the shoulder region R2 described above, the number of types of pitch length in the shoulder region R2 is less than the number of types of pitch length in the central region R1, or the shoulder The ratio between the maximum pitch length and the minimum pitch length in the region R2 may be smaller than the ratio between the maximum pitch length and the minimum pitch length in the central region R1. Or it is good to adjust combining these methods mutually. Thereby, the change of the pattern noise at the time when the shoulder region R2 is grounded can be further increased.

  More preferably, the total pitch number in the shoulder region R2 is set to 1.25 times or more, preferably 1.5 to 3.0 times the total pitch number in the central region R1. Here, when the total number of pitches in the shoulder region R2 is less than 1.25 times the total number of pitches in the central region R1, the change in the pattern noise at the time when the shoulder region R2 contacts the ground is slightly reduced, so the wear limit is limited. There is a risk that it will be difficult to recognize that you are approaching. However, if this value is increased too much, the rigidity of the block 3 in the shoulder region R2 is reduced, so that the pattern noise generated from the shoulder region R2 is reduced, so that the wear limit is approaching as described above. It may be difficult to recognize.

  Further, in the shoulder region R2, two types of pitches (block 3) having a pitch length ratio of 1.1 to 2.0, preferably 1.26 to 1.50 are alternately set to 1 to 4 in the tire circumferential direction. It is good to arrange at a period. Thereby, the pattern noise generated from the shoulder region R2 can be reliably increased. FIG. 4 shows a state in which the pitches arranged in the shoulder region R2 are two types A and B having different pitch length ratios, and these A and B are alternately arranged in the circumferential direction of the tire T in two cycles. Show.

  In the pneumatic tire of the present invention, one pitch can be arranged in the shoulder region R2 to form a single pitch configuration. Thereby, the pattern noise generated from the shoulder region R2 can be more reliably increased.

  As illustrated in FIG. 1, the pitch arrangement in the shoulder region R <b> 2 in the present invention may be configured by a block row partitioned into lug grooves 6 extending in the tire width direction. In this case, the angle of the lug groove 6 with respect to the tire circumferential direction is approximately 90 °, preferably 60 ° or more, and most preferably 80 to 90 °. As a result, since the entire length of the lug groove 6 comes into contact with the road surface at the same time, the sound pressure level of the pattern noise generated from the shoulder region R2 is changed to the pattern noise generated from the central region R1 as shown in FIG. The sound pressure level can be increased.

  Here, when the angle of the lug groove 4 with respect to the tire circumferential direction is set low, the longitudinal direction of the lug groove 6 intersects the front contact edge of the tire when the lug groove 6 contacts the road surface. Therefore, the sound pressure level of the pattern noise generated from the shoulder region R2 is lower than the sound pressure level of the noise generated from the central region R1. 5 shows noise characteristics when the angle of the lug groove 6 with respect to the tire circumferential direction is set to 60 °, and FIG. 6 shows noise characteristics when this angle is set to 30 °.

  As described above, the pneumatic tire of the present invention reaches at least 100% of the wear limit on both sides of the design element disposed in the central region R1 where the tread wear reaches the ground until 50 to 80% of the wear limit. By changing the design elements placed in the shoulder areas R2 and R2 that are in contact with each other, the tire replacement period is recognized by the change in pattern noise generated from the tire when wear progresses and approaches the wear limit. Thus, the wear limit can be easily and accurately determined without providing any special determination means, and thus can be widely used as a tire wear limit determination method.

  With the tire size set to 195 / 70R17.5 and the tire pattern shown in FIG. In the left and right shoulder regions R2 and R2, tires of the present invention were manufactured by setting the tread width to 10 mm, the number of types of pitch length to 1 (single pitch), and the total number of pitches to 114, respectively.

  This tire is installed in a wheel with a rim size of 17.5 x 5.25, filled with air pressure of 600 kPa and mounted on the front and rear wheels of a vehicle with a displacement of 3000 cc, and the general road is run until the tread wear reaches 45% of the wear limit. Afterwards, in order to investigate the occurrence of in-vehicle noise due to pattern noise at the end of wear, the in-vehicle noise (dB) when driving on an asphalt road test course at an average speed of 70 km / h is displayed on the driver's seat window side. Measured with an installed microphone. Through this running test at the end of wear, it was confirmed by hearing that the pattern noise generated from the tire gradually increased from the time when the amount of wear reached 50% of the wear limit. When this situation was verified by collating with the measurement result of the in-vehicle noise by the microphone, it was confirmed that the in-vehicle noise in the region near the frequency of 975 Hz was increased from 71 dB to 75 dB from the time when the wear limit reached 60%.

It is a partial top view which expands and shows an example of the tread surface of the pneumatic tire by the embodiment of the present invention. FIG. 2 is a half sectional view showing a structure of a tread portion of the tire of FIG. 1. (A) And (b) is a graph which shows the noise characteristic of the tire in a wear initial stage and a wear end stage, respectively. It is explanatory drawing which shows an example of the block arrangement | sequence in a shoulder area | region. It is a graph equivalent to FIG.3 (b) which shows the noise characteristic when the angle of the lug groove in a shoulder area | region is set to 60 degrees with respect to the tire circumferential direction. It is a graph equivalent to FIG.3 (b) which shows the noise characteristic when the angle of the lug groove in a shoulder area | region is set to 30 degrees with respect to the tire circumferential direction.

Explanation of symbols

1 tread surface 2, 3 blocks 4 tread portion 5 main groove 6 lug groove R1 central region R2 shoulder region Y tire circumferential direction

Claims (9)

In a pneumatic tire in which design elements composed of a combination of a plurality of pitches having different pitch lengths with respect to the tire circumferential direction are arranged on the tread surface,
The design element is differentiated between a central region where the tread wear is grounded to 50-80% of the wear limit and a shoulder region which is grounded to at least 100% of the wear limit on both sides of the central region; A pneumatic tire in which frequency dispersion of pattern noise generated by a design element in a region is different from frequency dispersion of pattern noise generated by a design element in the shoulder region.   The pneumatic tire according to claim 1, wherein a sound pressure level of pattern noise generated by the design element in the shoulder region is larger than a sound pressure level of pattern noise generated by the design element in the central region.   The pneumatic tire according to claim 2, wherein the number of types of pitch length in the shoulder region is smaller than the number of types of pitch length in the central region.   The pneumatic tire according to claim 2 or 3, wherein a ratio between the maximum pitch length and the minimum pitch length in the shoulder region is smaller than a ratio between the maximum pitch length and the minimum pitch length in the central region.   The pneumatic tire according to any one of claims 2 to 4, wherein the total number of pitches in the shoulder region is 1.25 times or more the total number of pitches in the central region.   6. The device according to claim 2, wherein two kinds of pitches having a pitch length ratio of 1.1 to 2.0 are alternately arranged in the tire circumferential direction at a cycle of 1 to 4 in the shoulder region. Pneumatic tires.   The pneumatic tire according to any one of claims 1 to 6, wherein the pitch array in the shoulder region is configured by a block row partitioned into lug grooves extending in a tire width direction.   The pneumatic tire according to claim 7, wherein an angle of the lug groove with respect to a tire circumferential direction is set to 60 ° or more.   A method for determining the wear limit of a pneumatic tire, wherein the tire replacement timing is determined based on a change in frequency dispersion of pattern noise generated by the pneumatic tire according to any one of claims 1 to 8.

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