JP7115921B2 - Method and apparatus for determining heel-and-toe wear of pneumatic tires - Google Patents

Description

The present invention relates to a method and apparatus for determining heel-and-toe wear of pneumatic tires.

In pneumatic tires mounted on automobiles, various uneven wear occurs depending on the tread pattern. For example, in a tire having a block-shaped tread portion, uneven wear may occur in which the kick-out side of the block-shaped tread portion is largely worn out of the step-in side and the kick-out side. This uneven wear is called heel-and-toe wear. Heel-and-toe wear degrades tire performance and increases noise, so it is required to be accurately detected and dealt with.

Patent Literature 1 discloses a method of measuring the amount of wear of a tire by measuring the sound pressure level for each frequency in the pattern noise of the tire and performing a comparison operation with the sound pressure level of a reference tire.

JP-A-2000-346755

The method of measuring the amount of tire wear disclosed in Patent Document 1 measures general wear and cannot effectively measure specific uneven wear. Therefore, there is room for improvement in determining whether or not heel-and-toe wear occurs as specific uneven wear.

An object of the present invention is to accurately determine whether or not heel-and-toe wear occurs in a method and apparatus for determining heel-and-toe wear of a pneumatic tire.

In a first aspect of the present invention, a pneumatic tire is rolled at a predetermined speed, the sound pressure of pattern noise is measured, the energy value is calculated in a predetermined frequency range from the measured sound pressure of the pattern noise, and the Determining that heel-and-toe wear has occurred if the energy value calculated in comparison with the energy value in a new state in a predetermined frequency range is greater than a predetermined value, wherein the predetermined frequency range is defined as the predetermined speed. and the minimum pitch length Dmin and the maximum pitch length Dmax of the block pitches in the tire circumferential direction of the tread pattern of the pneumatic tire corresponding to Δf in the following formula . A method for determining heel-and-toe wear of a pneumatic tire is provided .

According to this method, the sound pressure of the pattern noise is measured, and if the measured energy value is greater than the energy value when new in a predetermined frequency range by a predetermined value or more, it is determined that the device is worn. Therefore, it is possible to determine whether wear corresponding to a specific frequency range has occurred. Specifically, in the tread pattern of a tire, when blocks are arranged at predetermined intervals with variations in the tire circumferential direction, pattern noise increases in a predetermined frequency range due to heel-and-toe wear. Therefore, it is possible to determine whether or not heel-and-toe wear has occurred by comparing the energy values of a new tire and a measured tire in the frequency range. In particular, this judgment method enables the generation of heel-and-toe wear, which is difficult to accurately measure by comparing the sound pressure of pattern noise at a single frequency, by comparing the energy in a specific frequency range. It is what I did. Also, the predetermined frequency range Δf can be defined specifically. Specifically, when obtaining the lower limit value f1 and the upper limit value f2 of the frequency range Δf, the speed per second (m/s) is converted by multiplying the speed per hour V (km/h) by 1000/3600. The lower limit f1 of the frequency range Δf is obtained by dividing the speed per second V (km/h) per second by 1.05 times the maximum pitch length Dmax. Similarly, the upper limit value f2 of the frequency range Δf can be obtained by dividing the speed per second V (km/h) per second by 0.95 times the minimum pitch length Dmin. The reason why the maximum pitch length Dmax is multiplied by 1.05 and the minimum pitch length Dmin is multiplied by 0.95 is to provide a margin in the frequency range for calculating the energy value.

In the method, the block pitch is the primary pitch, and the predetermined frequency range is calculated for each order pitch according to the division shape of the blocks in the tire circumferential direction, and energy is generated in the predetermined frequency range for each order. It may be determined that heel-and-toe wear has occurred if the calculated energy value is greater than a predetermined value by comparing with the energy value when new for each order.

According to this method, since the energy value of the new product is compared with the measured energy value for each order of the pattern noise, more detailed determination can be performed. Specifically, when one block is divided in the tire circumferential direction by sipes or other fine grooves, pattern noise occurs at a frequency higher than the block pitch. The high-frequency pattern noise is called secondary, tertiary, quaternary, and so on. For example, if a block is evenly divided into two in the tire circumferential direction by sipes, secondary pattern noise is generated. The secondary pattern noise has a frequency twice that of the primary pattern noise (block pitch pattern noise). In this way, by considering the order and comparing energies in units that are more detailed than in units of blocks, heel-and-toe wear can be evaluated in more detail.

In a second aspect of the present invention, a pneumatic tire is rolled at a predetermined speed, the sound pressure of pattern noise is measured, the energy value is calculated in a predetermined frequency range from the measured sound pressure of the pattern noise, and the determining that heel-and-toe wear has occurred if the energy value calculated by comparing with the energy value when new in a predetermined frequency range is greater than a predetermined value, and comparing the energy value with the energy value when new. Provided is a method for determining heel-and-toe wear of a pneumatic tire, wherein it is determined that heel-and-toe wear has occurred if the calculated energy value is twice or more.

According to this method, the sound pressure of the pattern noise is measured, and if the measured energy value is greater than the energy value when new in a predetermined frequency range by a predetermined value or more, it is determined that the device is worn. Therefore, it is possible to determine whether wear corresponding to a specific frequency range has occurred. Specifically, in the tread pattern of a tire, when blocks are arranged at predetermined intervals with variations in the tire circumferential direction, pattern noise increases in a predetermined frequency range due to heel-and-toe wear. Therefore, it is possible to determine whether or not heel-and-toe wear has occurred by comparing the energy values of the new tire and the measured tire in the frequency range. In particular, this judgment method enables the generation of heel-and-toe wear, which is difficult to accurately measure by comparing the sound pressure of pattern noise at a single frequency, by comparing the energy in a specific frequency range. It is what I did. Also, when comparing energies, the presence or absence of occurrence of heel-and-toe wear is determined using a threshold value of 2 times. This is because when the energy value of the pattern noise is doubled, the difference is noticeable even to a general driver, and the noise often stands out. In addition, since the energy value is doubled as the threshold value, even if the measured energy value changes slightly due to the influence of external disturbances such as wind and road surface conditions, it will not cause heel-and-toe wear. Presence or absence can be determined accurately.

In a third aspect of the present invention, a pneumatic tire is rolled at a predetermined speed, the sound pressure of pattern noise is measured, the energy value is calculated in a predetermined frequency range from the measured sound pressure of the pattern noise, and the Determining that heel-and-toe wear has occurred if the energy value calculated in comparison with the energy value in a new state in a predetermined frequency range is greater than a predetermined value ; A method is provided for determining heel-and-toe wear of a pneumatic tire, which is a speed outside the resonant frequency range.

According to this method, the sound pressure of the pattern noise is measured, and if the measured energy value is greater than the energy value when new in a predetermined frequency range by a predetermined value or more, it is determined that the device is worn. Therefore, it is possible to determine whether wear corresponding to a specific frequency range has occurred. Specifically, in the tread pattern of a tire, when blocks are arranged at predetermined intervals with variations in the tire circumferential direction, pattern noise increases in a predetermined frequency range due to heel-and-toe wear. Therefore, it is possible to determine whether or not heel-and-toe wear has occurred by comparing the energy values of the new tire and the measured tire in the frequency range. In particular, this judgment method enables the generation of heel-and-toe wear, which is difficult to accurately measure by comparing the sound pressure of pattern noise at a single frequency, by comparing the energy in a specific frequency range. It is what I did. Also, pattern noise can be prevented from being affected by air columnar resonance of the circumferential grooves of the tread portion of the tire. If the evaluation is made at the speed at which the frequency range of the pattern noise and the frequency range of the air columnar resonance match, the groove becomes shallower with each wear, so the influence of the air columnar resonance is reduced. That is, the influence of air columnar resonance during evaluation is not constant. Therefore, pattern noise can be accurately measured by setting a predetermined speed such that a predetermined frequency range is outside the air columnar resonance frequency range.

In the method, a sound pressure sensor may be installed in front of the pneumatic tire in the rolling direction, and the sound pressure of the pattern noise may be measured by the sound pressure sensor.

According to this method, since the pattern noise appears clearly and strongly in front of the rolling direction of the tire, the sound pressure of the pattern noise can be efficiently measured. On the other hand, behind the rolling direction of the tire, there is a risk that the sound generated by the rubbing and sliding of the tire when kicking off the ground may be mixed with the pattern noise, and the sound pressure sensor may be damaged by flying stones etc. There is also sex. The sound pressure of pattern noise is often low on the sides of the rolling direction of the tire. Therefore, it is preferable to measure the pattern noise forward in the rolling direction of the tire.

In a fourth aspect of the present invention, the pneumatic tire is rolled at a predetermined speed, the sound pressure of pattern noise is measured, the energy value is calculated in a predetermined frequency range from the measured sound pressure of the pattern noise, and the determining that heel-and-toe wear has occurred if the energy value calculated in comparison with the energy value in a new state in a predetermined frequency range is greater than a predetermined value ; The sound pressure sensor is installed in the vehicle interior of the vehicle, the sound pressure of the pattern noise is measured by the sound pressure sensor, and the predetermined speed is determined by the predetermined speed. A method for determining heel-and-toe wear of a pneumatic tire is provided, wherein the frequency range is a velocity that falls within the vehicle's interior resonance range.

According to this method, the pattern noise can be efficiently amplified by the vehicle interior resonance, and the sound pressure of the pattern noise can be measured. Vehicle interior resonance occurs in a frequency range depending on the size and shape of the vehicle interior. Since the resonant frequency changes depending on the position in the vehicle, it is defined as a range such as the vehicle interior resonance range. Therefore, preferably, the predetermined speed is a speed that matches the vehicle interior resonance frequency at the position where the sound pressure sensor is installed.

A fifth aspect of the present invention is a rolling device that rolls a pneumatic tire at a predetermined speed, a sound pressure sensor that measures the sound pressure of pattern noise, and a predetermined frequency range from the measured sound pressure of the pattern noise. a storage unit that stores the energy value in the predetermined frequency range when new, and the energy calculation unit that compares the energy value in the storage unit with the energy value when the product is new. a judgment unit that judges that heel-and-toe wear has occurred if the energy value obtained is greater than a predetermined value , wherein the predetermined frequency range includes a vehicle speed V per hour corresponding to the predetermined speed and the pneumatic tire. Provide a device for determining heel-and-toe wear of a pneumatic tire, which is calculated as Δf by the following formula using the minimum pitch length Dmin and the maximum pitch length Dmax of the block pitches in the tire circumferential direction of the tread pattern do.

According to the present invention, in a method and apparatus for determining heel-and-toe wear of a pneumatic tire, the energy value in a predetermined frequency range is calculated from the measured pattern noise, and the calculated energy value is compared with the energy value when the tire is new. By doing so, heel-and-toe wear can be accurately determined.

1 is a perspective view of a pneumatic tire; FIG. A development view of a portion of the tread pattern. FIG. 2 is a plan view of a pneumatic tire showing the installation positions of microphones; The side view of the rolling device of a pneumatic tire. The top view of the rolling device of a pneumatic tire. A block diagram of a control device. A graph showing the relationship between pattern noise frequency and sound pressure. The side view of the modification of the rolling device of a pneumatic tire.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In this embodiment, it is determined whether heel-and-toe wear of the pneumatic tire has occurred. The pneumatic tire 1 can be, for example, a common passenger car tire. Alternatively, it may be a truck or bus tire or the like. Henceforth, the pneumatic tire 1 is also simply referred to as the tire 1 .

Referring to FIG. 1, a tire 1 is mounted on a wheel rim 2. As shown in FIG. A tire 1 rolls on a road surface while being mounted on a wheel rim 2. - 特許庁When the tire 1 rolls on the road surface, pattern noise corresponding to the tread pattern of the tire 1 is generated. The determination method of the present embodiment determines whether or not heel-and-toe wear occurs by measuring the pattern noise. Note that illustration of the tread pattern is omitted in FIG.

Since the pattern noise may differ depending on the road surface condition, it is preferable to measure the pattern noise under a constant road surface condition in order to make an accurate determination. For example, JIS D 8301:2013 (ISO 10844:2011) may be used as the constant road surface condition.

FIG. 2 shows a developed view of part of the tread portion 10 of the tire 1 (see hatched portion in FIG. 1). Blocks 13 defined by longitudinal grooves 11 extending in the tire circumferential direction TR and lateral grooves 12 extending in the tire width direction TW are formed in the tread portion 10 .

Generally, in a tire, the blocks 13 are not formed with completely the same pitch in the tire circumferential direction TR, but are formed with slightly different pitches. As a result, pattern noise generation frequencies are not concentrated on one frequency, and thus the sound pressure of one frequency is prevented from being significantly increased. Also in this embodiment, the blocks 13 are formed at slightly different pitches in the tire circumferential direction TR. Hereinafter, the formation pitch of the blocks 13 slightly varying in the tire circumferential direction TR is also referred to as a block pitch. This block pitch is represented by D1 in FIG. 2, for example.

FIG. 3 shows a plan view of the tire 1. FIG. A microphone (sound pressure sensor) 20 is used to measure pattern noise. Preferably, the microphone 20 is installed on the front side Fr of the tire 1 in the rolling direction. More specifically, the microphone 20 is preferably installed in an equilateral triangular region S1 having one side equal to the width of the tire 1 in plan view. This is because large pattern noise can be clearly measured in front of the tire 1 at the instant when the block 13 touches the ground. Alternatively, the microphone 20 may be installed behind the tire 1 in the rolling direction. Specifically, the microphone 20 may be installed in an equilateral triangular area S2 having one side equal to the width of the tire 1 in plan view. Further alternatively, the microphone 20 may be installed laterally of the tire 1 . Specifically, the microphone 20 may be installed in an equilateral triangular region S3 having one side equal to the length of the tire 1 in plan view. Moreover, it is preferable that the microphone 20 is installed in the range from the ground to the center of the tire in the tire height direction. A member indicated by reference numeral 32 in FIG. 3 indicates a support portion 32 which will be described later.

In this embodiment, a determination device for determining heel-and-toe wear of the tire 1 is used.

The determination device includes a rolling device 30 that rolls the tire 1 at a predetermined speed, a microphone 20 that measures the sound pressure of pattern noise, a control device 40, and a monitor 50 that displays the determination result.

4 and 5, the rolling device 30 includes a road surface portion 31 on which the tire 1 is placed and a support portion 32 that supports the tire 1. As shown in FIG. The road surface portion 31 includes two rollers 31a and 31b and a belt 31c. The two rollers 31a and 31b are mechanically connected to a motor (not shown). The two rollers 31a and 31b are rotationally driven in the same direction by a motor. In addition, the belt 31c is stretched across the two rollers 31a and 31b so as to surround the two rollers 31a and 31b. Therefore, when the two rollers 31a and 31b rotate, the belt 31c rotates. The support portion 32 is a member that supports the tire 1 so as to be rotatable around the rotation axis La. The tire 1 is supported by the support portion 32 while being placed on the upper surface of the belt 31c. The speed of the motor that rotates the two rollers 31a and 31b is controlled by the controller 40. FIG. Accordingly, the tire 1 rolls on the belt 31c at a predetermined speed as the belt 31c rotates at a predetermined speed.

The type of microphone 20 is not particularly limited, and a commercially available one can be used. In this embodiment, the microphone 20 is installed in the front area S1 in the rolling direction of the tire 1 shown in FIG. As for the tire height direction, the microphone 20 is installed in a range from the surface of the road surface portion 31 on which the tire 1 is placed to the tire rotation axis La in FIG.

Referring to FIG. 6, control device 40 includes hardware including storage devices such as CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), and software implemented therein. Built by The control device 40 includes an energy calculation section 41 , a storage section 42 , a determination section 43 and a speed control section 44 .

The energy calculator 41 calculates an energy value in a predetermined frequency range from the sound pressure of pattern noise measured by the microphone 20 . The predetermined frequency range is calculated as Δf by the following formula. Here, V in the following equation is the vehicle speed V (km/h) corresponding to the rolling speed of the tire 1 . Also, Dmax indicates the maximum pitch length among the block pitches described above, and Dmin indicates the minimum pitch length.

A method of calculating the frequency range Δf using the above formula will be exemplified using specific numerical values. In this embodiment, a tire 1 having a radius of 300 mm and having 34 blocks 13 per circumference of the tire 1 is used. The minimum pitch length Dmin is 42 mm, the maximum pitch length Dmax is 69 mm and the basic block pitch is 55 mm. That is, a variation of about 25% is set with respect to the basic block pitch. Also, the predetermined speed is assumed to be 50 km/h. Substituting these into the above equation, the lower limit value f1 is 191 Hz and the upper limit value f2 is 352 Hz. Therefore, the frequency range Δf is 191-352 Hz.

The energy value in the frequency range Δf is calculated as E by the following formula. Here, Pi in the following equation indicates sound pressure at a certain frequency fi. Note that the frequency fi is a value within the frequency range Δf (f1≦fi≦f2). For example, in the case of the frequency range Δf (191 to 352 Hz) shown as the numerical example above, the frequency fi may be set every 1 Hz from 191 to 352 Hz.

The storage unit 42 stores, as E0, the energy value E in the same frequency range Δf of the new tire 1 calculated by the above formula.

The determination unit 43 determines that heel-and-toe wear is occurring if the energy value E calculated by the energy calculation unit 41 is larger than a predetermined value as compared with the energy value E0 of the new product stored in the storage unit 42, and so. If not, it is determined that heel-and-toe wear has not occurred. This is because as heel-and-toe wear progresses, the difference in height between the stepping-in side and the kicking-out side of the block 13 increases, and pattern noise increases. In this embodiment, if the measured energy value E is two times or more the energy value E0 of the new product, it is determined that heel-and-toe wear has occurred. Otherwise, heel-and-toe wear has occurred. determine that it is not. The effectiveness of this determination will be described later.

The determination result of the determination unit 43 is displayed on the monitor 50 as needed. In particular, a warning may be displayed on the monitor 50 when the determination unit 43 determines that there is wear.

In this embodiment, the concept of "order" according to the tread pattern is introduced in order to determine the presence or absence of heel-and-toe wear in more detail. Specifically, the block pitch described above is used as the primary pitch. Higher orders such as secondary, tertiary, quaternary, . The frequency range Δf is calculated for each order pitch, the energy value E is calculated in the frequency range Δf for each order, and the calculated energy value E is compared with the energy value E0 when new for each order. If so, it is determined that heel-and-toe wear has occurred.

Specifically, referring to FIG. 2, if the above-described block pitch (primary pitch length) is D1, a secondary pitch length D2 approximately half the primary pitch length D1 and a quarter of D1 A fourth order pitch length D4 of the order of 1 is provided. Higher order pitch lengths, such as the secondary pitch length D2 and the quaternary pitch length D4, are provided based on how many blocks 13 are divided by the lateral grooves 14,15. Therefore, in this embodiment, the frequency range Δf is calculated not only for the first order but also for the second order and the fourth order, the energy value E is calculated, and the wear determination is performed by comparing with the energy value E0 when new. Note that the frequency range Δf of the second and subsequent orders can be obtained by multiplying the frequency range Δf of the first order by its order. That is, in the numerical example above, since the frequency range Δf of the first order is 191 to 352 Hz, the frequency range Δf of the second order is doubled to 382 to 704 Hz, and the frequency range Δf of the fourth order is four times to 764 to 1408 Hz. becomes.

FIG. 7 shows a graph of an example of measured pattern noise. The horizontal axis of the graph indicates frequency [Hz], and the vertical axis indicates sound pressure level [dB]. The pattern noise frequency corresponding to the pitch length D1 of the first order is about 250 Hz, the pattern noise frequency corresponding to the pitch length D2 of the second order is about 500 Hz, and the pattern noise frequency corresponding to the pitch length D4 of the fourth order is about 500 Hz. It is 1000 Hz, and the peak value of the sound pressure level can be confirmed at these frequencies. More specifically, the sound pressure level does not increase only at each point of these frequencies, but the sound pressure level increases over a certain width around these frequencies. This is because the pitch lengths D1, D2, and D4 of each order are set with variations. Therefore, when performing wear determination, it is effective to perform energy comparison in a frequency range around the peak value, instead of comparing sound pressure at a single frequency having a peak value. Therefore, in the present embodiment, energy comparison is performed in the frequency range Δf around the peak value of each order to determine the presence or absence of heel-and-toe wear.

The speed control unit 44 of this embodiment controls the motor that rotates the two rollers 31a and 31b. Therefore, the speed control unit 44 can control the rolling speed of the tire 1 and adjust the frequency range Δf. Preferably, the speed V is controlled so that the frequency range Δf deviates from the air column resonance frequency range Δg of the longitudinal grooves 11 of the tire 1 . The air column resonance frequency range Δg is obtained by the following formula. Here, c is the speed of sound and L is the pipe length of the flute 11 . α is a correction coefficient and takes a value of 0.6 or more and 0.8 or less.

A method of calculating the frequency range Δf using the above formula will be exemplified using specific numerical values. Assuming that the tube length L of the vertical groove 11 is 120 mm and the sound velocity c is 340 (m/s), the air columnar resonance frequency range Δg takes a value of 850 to 1133 Hz. Therefore, it is preferable that the speed control unit 44 sets the speed V so as to avoid the range Δg thus obtained and set the frequency range Δf.

However, it may be difficult to remove the frequency range Δf of all orders from the air column resonance frequency range Δg. In the numerical example of the present embodiment as well, the fourth order frequency range Δf (764 to 1408 Hz) and the air column resonance frequency range Δg (850 to 1133 Hz) overlap. Thus, when it is difficult to remove the frequency range Δf of all orders from the air column resonance frequency range Δg, the frequency range Δf of the most conspicuous order may be removed from the air column resonance frequency range Δg. For example, in the example of this embodiment shown in FIG. 7, since the sound pressure level of the 4th order pattern noise (near 1000 Hz) is the most conspicuous, the speed V is changed to adjust only the 4th order frequency range Δf to the air columnar resonance frequency. It may be outside the range Δg. In addition, the velocity V may be changed to remove the frequency range Δf of the second most prominent order from the air column resonance frequency range Δg.

The method and apparatus for determining heel-and-toe wear of a pneumatic tire according to this embodiment have the following merits.

In this embodiment, the sound pressure of the pattern noise is measured, and if the measured energy value E is greater than the energy value E0 when new in a predetermined frequency range Δf by a predetermined value or more, it is determined that there is wear. Therefore, it is possible to determine whether or not wear corresponding to the specific frequency range Δf has occurred. Specifically, in the tread pattern of the tire 1, when the blocks 13 are arranged at predetermined intervals with variations in the tire circumferential direction TR, pattern noise occurs in a predetermined frequency range Δf due to heel-and-toe wear. To increase. Therefore, it is possible to determine whether or not heel-and-toe wear has occurred by comparing the energy values of the new tire and the measured tire in the frequency range Δf. In particular, this judgment method enables the occurrence of heel-and-toe wear, which is difficult to accurately measure by comparing the sound pressure of pattern noise at a single frequency, by comparing the energy in a specific frequency range Δf. It is the one that was made.

Moreover, in this embodiment, the predetermined frequency range Δf is specifically defined. Specifically, when obtaining the lower limit value f1 and the upper limit value f2 of the frequency range Δf, the speed per second (m/s) is converted by multiplying the speed per hour V (km/h) by 1000/3600. The lower limit f1 of the frequency range Δf is obtained by dividing the speed per second V (km/h) per second by 1.05 times the maximum pitch length Dmax. Similarly, the upper limit value f2 of the frequency range Δf can be obtained by dividing the speed per second V (km/h) per second by 0.95 times the minimum pitch length Dmin. The reason why the maximum pitch length Dmax is multiplied by 1.05 and the minimum pitch length Dmin is multiplied by 0.95 is to provide a margin in the frequency range for calculating the energy value.

Further, in this embodiment, the energy value E0 at the time of new product and the measured energy value E are compared for each order of pattern noise, so that more detailed determination is performed. Specifically, when one block 13 is divided in the tire circumferential direction TR by sipes or other fine grooves, pattern noise occurs at a frequency higher than the block pitch. In this way, by evaluating high-frequency pattern noise in consideration of the order, energy comparison can be performed in units more detailed than block units, and heel-and-toe wear can be evaluated in more detail.

In addition, in the present embodiment, the presence or absence of occurrence of heel-and-toe wear is determined using a threshold value of twice the energy when comparing the energies. This is because when the energy value of the pattern noise is doubled, the difference is noticeable even to a general driver, and the noise often stands out. In addition, since the energy value is doubled as the threshold value, even if the measured energy value changes slightly due to the influence of disturbances such as wind and road surface conditions, it will not cause heel-and-toe wear. Presence or absence can be determined accurately.

Further, in this embodiment, since the predetermined speed is set so that the predetermined frequency range is outside the air columnar resonance frequency range, the pattern noise is affected by air columnar resonance in the circumferential grooves of the tread portion of the tire. can prevent you from receiving If the evaluation is made at the speed at which the frequency range of the pattern noise and the frequency range of the air columnar resonance match, the groove becomes shallower with each wear, so the influence of the air columnar resonance is reduced. That is, the influence of air columnar resonance during evaluation is not constant. Therefore, pattern noise can be accurately measured by setting a predetermined speed such that a predetermined frequency range is outside the air columnar resonance frequency range.

Further, in the present embodiment, the pattern noise is measured in the region S1 (see FIG. 3) in front Fr of the tire 1 in the rolling direction. As a result, the pattern noise appears clearly and strongly in the front Fr in the rolling direction of the tire 1, so the sound pressure of the pattern noise can be efficiently measured.

As described above, specific embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

For example, the road surface portion 31 of the rolling device 30 may not be flat. Specifically, as shown in FIG. 8 , the road surface portion 31 may include a rotatable drum 31 d having a sufficiently large radius of curvature compared to the tire 1 .

Alternatively, rolling device 30 may be an actual automobile. In this case, it is preferable to run the vehicle at a speed in which the predetermined frequency range Δf is included in the vehicle interior resonance range. As a result, the pattern noise can be efficiently amplified by the vehicle interior resonance, and the sound pressure of the pattern noise can be measured. Vehicle interior resonance occurs in a frequency range depending on the size and shape of the vehicle interior. Since the resonant frequency changes depending on the position in the vehicle, it is defined as a range such as the vehicle interior resonance range. Therefore, preferably, the travel speed is a speed that matches the vehicle interior resonance frequency at the location where the microphone 20 is mounted.

1 pneumatic tire (tyre)
2 wheel rim 10 tread portion 11 longitudinal groove
12 Yokomizo
13 blocks 14, 15 lateral grooves 20 microphone (sound pressure sensor)
30 rolling device (automobile)
31 road surface portion 31a, 31b roller 31c belt 31d drum 32 support portion 40 control device 41 energy calculation portion 42 storage portion 43 determination portion 44 speed control portion 50 monitor

Claims (7)

Roll the pneumatic tire at a predetermined speed,
Measure the sound pressure of the pattern noise,
calculating an energy value in a predetermined frequency range from the measured sound pressure of the pattern noise;
If the energy value calculated in comparison with the energy value in the new state in the predetermined frequency range is greater than a predetermined value, it is determined that heel-and-toe wear has occurred.
including
The predetermined frequency range is obtained by using the speed V of the vehicle corresponding to the predetermined speed and the minimum pitch length Dmin and the maximum pitch length Dmax of block pitches in the tire circumferential direction of the tread pattern of the pneumatic tire, A method for determining heel-and-toe wear of a pneumatic tire, which is calculated as Δf by the following formula.

With the block pitch as the primary pitch, the predetermined frequency range is calculated at each order pitch according to the division shape of the blocks in the tire circumferential direction,
calculating an energy value in the predetermined frequency range for each order;
2. A pneumatic tire according to claim 1 , wherein heel-and-toe wear is determined to occur if the energy value calculated by comparing with the energy value when the tire is new is greater than a predetermined value for each order. judgment method. Roll the pneumatic tire at a predetermined speed,
Measure the sound pressure of the pattern noise,
calculating an energy value in a predetermined frequency range from the measured sound pressure of the pattern noise;
If the energy value calculated in comparison with the energy value in the new state in the predetermined frequency range is greater than a predetermined value, it is determined that heel-and-toe wear has occurred.
including
A method for determining heel-and-toe wear of a pneumatic tire, wherein it is determined that heel-and-toe wear has occurred if the calculated energy value is greater than twice the energy value when the tire is new. Roll the pneumatic tire at a predetermined speed,
Measure the sound pressure of the pattern noise,
calculating an energy value in a predetermined frequency range from the measured sound pressure of the pattern noise;
If the energy value calculated in comparison with the energy value in the new state in the predetermined frequency range is greater than a predetermined value, it is determined that heel-and-toe wear has occurred.
including
The method for determining heel-and-toe wear of a pneumatic tire, wherein the predetermined speed is a speed at which the predetermined frequency range deviates from the air column resonance frequency range. A sound pressure sensor is installed in front of the rolling direction of the pneumatic tire,
The method for determining heel-and-toe wear of a pneumatic tire according to any one of claims 1 to 4 , wherein the sound pressure of the pattern noise is measured by the sound pressure sensor. Roll the pneumatic tire at a predetermined speed,
Measure the sound pressure of the pattern noise,
calculating an energy value in a predetermined frequency range from the measured sound pressure of the pattern noise;
If the energy value calculated in comparison with the energy value in the new state in the predetermined frequency range is greater than a predetermined value, it is determined that heel-and-toe wear has occurred.
including
The rolling of the pneumatic tire is performed by actual driving of a vehicle equipped with the pneumatic tire,
A sound pressure sensor is installed in the vehicle interior of the automobile,
measuring the sound pressure of the pattern noise with the sound pressure sensor;
A method for determining heel-and-toe wear of a pneumatic tire, wherein the predetermined speed is a speed at which the predetermined frequency range is included in a vehicle interior resonance range of the automobile. A rolling device that rolls a pneumatic tire at a predetermined speed;
a sound pressure sensor for measuring the sound pressure of pattern noise;
an energy calculation unit that calculates an energy value in a predetermined frequency range from the measured sound pressure of the pattern noise;
a storage unit that stores energy values in the predetermined frequency range when the product is new;
a determination unit that determines that heel-and-toe wear has occurred if the energy value calculated by the energy calculation unit is greater than a predetermined value in comparison with the energy value in the new state of the storage unit ,
The predetermined frequency range is obtained by using the speed V of the vehicle corresponding to the predetermined speed and the minimum pitch length Dmin and the maximum pitch length Dmax of block pitches in the tire circumferential direction of the tread pattern of the pneumatic tire, A device for determining heel-and-toe wear of a pneumatic tire, which is calculated as Δf by the following formula .

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