JP2020046256A - Determination method and device for width-direction uneven wear of pneumatic tire - Google Patents

Abstract

To provide a determination method and device for width-direction uneven wear of a pneumatic tire that can correctly determine presence and absence of occurrence of the width-direction uneven wear.SOLUTION: The determination method of width-direction uneven wear of a pneumatic tire includes the processes of: installing a sensor 20 at an inner surface of a tire 1 located at a position corresponding to a shoulder portion 6, a quarter portion 7, and a center portion 8; measuring force of pattern vibration generated by each of the portions 6 to 8 using the sensor 20 by rolling the tire 1 in a new state at a predetermined speed; calculating a criterion energy value E0 based on the force of the pattern vibration measured on the tire 1 at the new state; measuring force of pattern vibration generated by each of the portions 6 to 8 using the sensor 20 by rolling the tire 1 to be measured at a predetermined speed; calculating a measurement energy value E based on the force of the pattern vibration measured on the tire 1 to be measured; and determining that width-direction uneven wear occurs when the measurement energy value E is smaller than the criterion energy value E0 by a predetermined value or more.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method and an apparatus for determining uneven wear in the width direction of a pneumatic tire.

  In a pneumatic tire mounted on an automobile or the like, various uneven wears occur according to a tread pattern. For example, in the shoulder portion, the quarter portion, and the center portion extending in the tire circumferential direction, any part may be worn more than other parts. Such wear is also referred to as uneven wear in the width direction. Since uneven wear in the width direction deteriorates tire performance, it is required to accurately detect and deal with the wear.

  Patent Literature 1 discloses a method of measuring the tire wear amount by measuring acceleration in a predetermined frequency band in a pattern vibration of a tire and performing a comparison operation with that of a reference tire.

JP 2008-132921 A

  The method for measuring the amount of wear of a tire disclosed in Patent Document 1 measures general wear, and cannot measure a specific uneven wear effectively. Therefore, there is room for improvement in terms of determining whether or not uneven wear in the width direction has occurred as specific uneven wear.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for determining uneven wear in the width direction of a pneumatic tire, which accurately determine whether or not uneven wear in the width direction has occurred.

  In a first aspect of the present invention, a sensor is installed on the inner surface of the pneumatic tire at a position corresponding to at least one of a shoulder portion, a quarter portion, and a center portion, and the pneumatic tire at the time of brand-new operation is set at a predetermined speed. Rolled to measure the acceleration or force of the pattern vibration generated by at least one of the shoulder portion, the quarter portion, and the center portion by the sensor, and the acceleration of the pattern vibration measured by the pneumatic tire when new. Alternatively, a pattern generated by calculating a reference value based on a force, rolling the pneumatic tire to be measured at a predetermined speed, and generating at least one of the shoulder portion, the quarter portion, and the center portion by the sensor. The acceleration or force of the vibration was measured, and the measurement was performed with the pneumatic tire to be measured. Calculating a measured value based on the acceleration or force of the turn vibration, including determining that uneven wear in the width direction has occurred if the measured value is smaller than the reference value by a predetermined amount or more, for a pneumatic tire. Provided is a method for determining uneven wear in the width direction.

  According to this method, a sensor installed at a position corresponding to at least one of the shoulder, the quarter, and the center in the tire width direction is used. Then, the presence or absence of non-uniform wear in the width direction is determined by measuring the acceleration or force of pattern vibration generated when these parts touch the ground with a sensor. Therefore, it is possible to determine whether or not wear has occurred in at least one of the shoulder portion, the quarter portion, and the center portion. Specifically, when wear of any one of the shoulder, the quarter, and the center progresses, the vibration of the part is reduced. In the above method, the presence or absence of uneven wear in the width direction is determined by comparing the reference value and the measured value to detect a decrease in the vibration. In particular, in this determination method, the presence or absence of uneven wear in the width direction can be accurately determined because the sensor is installed at a position corresponding to the portion to be determined. In addition, a new article means a thing which is not used or is not worn.

  In the method, the sensor is installed on an inner surface of the pneumatic tire at a position corresponding to each of the shoulder portion, the quarter portion, and the center portion, and the shoulder portion, the quarter portion, and the center are arranged by the sensor. Measure the acceleration or force of the pattern vibration generated by each of the portion, the shoulder portion, the quarter portion, and only one of the center portion, the measured value is smaller than the reference value by a predetermined value or more, and, If the measured value is not smaller than the reference value by a predetermined value or more in the remaining two, it may be determined that only the part where the measured value is smaller than the reference value by a predetermined value is unevenly worn.

  According to this method, it is possible to determine which of the shoulder, the quarter, and the center is worn. In other words, by installing sensors for each part, the wear state of all parts can be grasped. For this reason, it can be determined whether the entire wear is such that all the parts are worn uniformly, or whether the uneven wear is the wear of only any part.

  In the method, the reference value and the measured value may be calculated using only the data at the time of stepping and kicking out of the time series data of acceleration or force measured by the sensor.

  According to this method, clear data among the measured acceleration or force can be used. Particularly, large vibrations are generated at the time of stepping or kicking, so that useful data for calculating the reference value and the measured value can be obtained. Here, the time of stepping means from immediately before stepping to immediately after stepping. In addition, the time of kicking means a period immediately before the kicking, immediately after the kicking, or a certain time immediately after the kicking. Since the tire is in contact with the ground immediately after stepping on the tire to immediately before kicking, the acceleration or force measured by the sensor does not substantially vibrate.

  In the method, if the measured value is equal to or less than half of the reference value, it may be determined that uneven wear in the width direction has occurred.

  According to this method, the presence or absence of uneven wear in the width direction is determined using half as a threshold value. This is because if the threshold value is set at half, there is a difference that can be felt by a general driver. In addition, since the threshold value is set to half, even if the measured value slightly changes due to the influence of disturbance such as a road surface condition, the presence or absence of uneven wear in the width direction can be accurately determined without erroneous determination.

  The reference value is a reference energy value that is an energy value calculated in a predetermined frequency range from the acceleration or force of the pattern vibration measured with the pneumatic tire when new, and the measurement value is a measurement target. The measured energy value may be an energy value calculated in a predetermined frequency range from the acceleration or force of the pattern vibration measured by the pneumatic tire.

  According to this method, the occurrence of uneven wear in the width direction can be determined with high accuracy. Specifically, it is possible to generate uneven wear in the width direction, which is difficult to measure accurately by comparing the acceleration or force of the pattern vibration at a certain frequency, by comparing the energy in a specific frequency range.

  The predetermined frequency range, using the vehicle speed V corresponding to the predetermined speed, the minimum pitch length Dmin and the maximum pitch length Dmax of the block pitch in the tire circumferential direction of the tread pattern of the pneumatic tire, It may be calculated as Δf by the following equation.

  According to this method, the predetermined frequency range Δf can be specifically defined. In particular, a block having a predetermined pitch length may be formed in the shoulder, quarter, and center portions extending in the tire circumferential direction by forming grooves extending in the tire width direction. The block is grounded at a certain time interval with the rotation of the tire, and generates a pattern vibration. Therefore, by adjusting the predetermined frequency range for calculating the energy value to the frequency of occurrence of the pattern vibration, it is possible to accurately detect uneven wear in the width direction. It should be noted here that the block pitch is designed to have a certain degree of variation (Dmin to Dmax) in order to prevent the pattern vibration from concentrating on a specific frequency. Therefore, it is effective to calculate the energy value not in a specific frequency point corresponding to a specific block pitch but in a predetermined frequency range corresponding to a block pitch having a variation as shown in the above equation. In addition, in the above equation, when calculating the lower limit value f1 and the upper limit value f2 of the frequency range Δf, the speed is converted to the speed per second (m / s) by multiplying the speed per hour V (km / h) by 1000/3600. The lower limit value f1 of the frequency range Δf is obtained by dividing a value obtained by converting an hourly speed V (km / h) into a second speed by a value 1.05 times the maximum pitch length Dmax. Similarly, the upper limit value f2 of the frequency range Δf is obtained by dividing a value obtained by converting the speed per hour V (km / h) to a speed per second by a value 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 a frequency range for calculating an energy value.

  In the method, the block pitch is set as a primary pitch, and the predetermined frequency range is calculated at a pitch of each order according to a division shape of a block in the tire circumferential direction, and the predetermined frequency range is calculated for each order. Calculate a reference energy value and the measured energy value, respectively, and compare the reference energy value and the measured energy value for each order. If the measured energy value is smaller than the reference energy value by a predetermined amount or more, the width direction is non-uniform. It may be determined that wear has occurred.

  According to this method, the reference energy value and the measured energy value are compared for each order of the pattern vibration, so that a more detailed determination can be made. Specifically, when one block is divided in the tire circumferential direction by a sipe or other narrow groove, pattern vibration occurs at a frequency higher than the block pitch. The high frequency pattern vibration is referred to as second, third, fourth,. For example, if a block is equally divided into two in the tire circumferential direction by a sipe, a secondary pattern vibration occurs. The secondary pattern vibration has twice the frequency of the primary pattern vibration (pattern vibration due to the block pitch). In this way, by performing the energy comparison in a more detailed unit than the block unit in consideration of the order, the uneven wear in the width direction can be evaluated in more detail.

  The predetermined speed may be a speed at which the predetermined frequency range includes a cavity resonance range.

  According to this method, the pattern vibration can be efficiently amplified by the cavity resonance, and the acceleration or force of the pattern vibration can be measured. The cavity resonance range is a frequency range in which the pneumatic tire causes cavity resonance. Cavity resonance is a phenomenon in which a resonance mode generated in a cavity in a tire affects an axle. The cavity resonance occurs in a frequency range (cavity resonance range) corresponding to the tire shape and the like, and the cavity resonance range can be specified in advance. Here, it is assumed that the predetermined frequency range and the cavity resonance range partially overlap each other.

  The reference value is a reference acceleration or a reference force, which is a peak value of acceleration or force at the time of stepping or kicking of the pattern vibration measured by the pneumatic tire when new, and the measurement value is a measurement target. It may be a measured acceleration or a measured force which is a peak value of an acceleration or a force at the time of stepping or kicking of the pattern vibration measured by the pneumatic tire. The peak value may be a maximum value or a minimum value of the acceleration or the force, or may be a difference between the maximum value and the minimum value.

  According to this method, the occurrence of uneven wear in the width direction can be determined with high accuracy by comparing the acceleration or the force due to the pattern vibration at the time of stepping or kicking regardless of the frequency.

  A second aspect of the present invention provides a rolling device for rolling a pneumatic tire at a predetermined speed, and a rolling device installed on an inner surface of the pneumatic tire at a position corresponding to at least one of a shoulder portion, a quarter portion, and a center portion. A sensor for measuring an acceleration or force of a pattern vibration generated by at least one of the shoulder portion, the quarter portion, and the center portion of the pneumatic tire rolled by the rolling device; A storage unit that stores a reference value calculated from the acceleration or force of the pattern vibration when the pneumatic tire is rolled at the predetermined speed by the rolling device, and the pneumatic tire to be measured is A calculating unit that calculates a measurement value calculated from the acceleration or force of the pattern vibration measured by rolling at the predetermined speed by a rolling device; The measurements and a determination unit and the reference value more than the predetermined amount small Re Invite widthwise uneven wear than occurs to provide a determination device in the width direction uneven wear of a pneumatic tire.

  According to the present invention, in the method and the apparatus for determining uneven wear in the width direction of a pneumatic tire, since the sensors are installed at positions corresponding to the shoulder, the quarter, and the center, uneven wear in the width direction is reduced. Can be determined accurately.

The perspective view of a pneumatic tire. The development view of a part of tread pattern. The top view of the pneumatic tire which shows the installation position of a sensor. The side view of the rolling device of a pneumatic tire. The top view of the rolling device of a pneumatic tire. FIG. 3 is a block diagram of a control device. 9 is a graph showing the relationship between the force (acceleration) of pattern vibration and time. 9 is a graph showing a relationship between a frequency of pattern vibration and a force (acceleration). The side view of the modification of the rolling device of a pneumatic tire.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(1st Embodiment)
In the present embodiment, it is determined whether or not uneven wear in the width direction has occurred in the pneumatic tire. The pneumatic tire may be, for example, a general passenger car tire. Alternatively, it may be a truck or bus tire or the like. Hereinafter, a pneumatic tire is also simply referred to as a tire.

  With reference to FIG. 1, the tire 1 has a shoulder portion 6, a quarter portion 7, and a center portion 8 partitioned in the tire width direction TW by longitudinal grooves 11a to 11d extending in the tire circumferential direction TR. The shoulder portion 6, the quarter portion 7, and the center portion 8 are arranged in this order from both outer sides to the inner side in the tire width direction TW. The tire 1 is mounted on a wheel rim 2. The tire 1 rolls on a road surface while being mounted on the wheel rim 2. When the tire 1 rolls on the road surface, a pattern vibration corresponding to the tread pattern of the tire 1 occurs. The determination method of the present embodiment is to determine the occurrence of uneven wear in the width direction by measuring the pattern vibration. In FIG. 1, detailed illustration of the tread pattern is omitted.

  Since the pattern vibration may vary depending on the road surface condition, it is preferable to measure the pattern vibration under a constant road surface condition in order to make an accurate determination. As the constant road surface condition, for example, JIS D 8301: 2013 (ISO 10844: 2011) may be adopted.

  FIG. 2 is a development view of a part of the tread portion 5 of the tire 1 (see a hatched portion in FIG. 1). The shoulder portion 6 is divided into a plurality of blocks 13 by a plurality of lateral grooves 12 extending in the tire width direction TW. In other words, the block 13 is defined by the vertical groove 11d and the horizontal groove 12.

  The blocks 13 are not formed at exactly the same pitch in the tire circumferential direction TR, but are formed at slightly different pitches. As a result, the frequency of occurrence of the pattern vibration is not concentrated on one frequency, and the vibration of one frequency is prevented from becoming extremely large. This is a design often found in general tires. Hereinafter, the formation pitch of the blocks 13 having such slight variations in the tire circumferential direction TR is also referred to as block pitch. This block pitch is represented by, for example, D1 in FIG.

  FIG. 3 shows a plan view when the tire 1 is viewed from directly above. In order to measure the pattern vibration, the sensor 20 is used. The sensor 20 measures acceleration or force, and may be, for example, an acceleration sensor or a force sensor. The direction of the force (or acceleration) to be measured may be the radial direction or circumferential direction TR of the tire 1. In the present embodiment, the sensor 20 is a force sensor, and the sensor 20 can measure a force applied to the tire 1. In the following description, since the measurement target of the sensor 20 is a force, the force will be described as an example. Alternatively, when the measurement target of the sensor 20 is an acceleration, the following description of “force” may be replaced with “acceleration”.

  The sensor 20 is installed on the inner surface of the tire 1 at a position corresponding to at least one of the shoulder portion 6, the quarter portion 7, and the center portion 8 in the tire width direction TW of the tire 1. In the present embodiment, the sensor 20 is attached to each of the inner surfaces of the shoulder portion 6, the quarter portion 7, and the center portion 8. The type of the sensor 20 is not particularly limited, and a commercially available sensor can be used.

  In the present embodiment, a determination device for determining the presence or absence of uneven wear of the tire 1 in the width direction is used.

  The determining device includes a rolling device 30 (see FIG. 4) for rolling the tire 1 at a predetermined speed, a sensor 20 (see FIG. 3) for measuring the force of the pattern vibration, a control device 40 (see FIG. 6), A monitor 50 (see FIG. 6) for displaying the determination result.

  Referring to FIGS. 4 and 5, rolling device 30 includes a road surface portion 31 on which tire 1 is mounted, and a support portion 32 for supporting tire 1. The road surface section 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 driven to rotate in the same direction by a motor. The belt 31c is stretched over 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 rotatably around the rotation axis La. The tire 1 is supported by the support portion 32 while being mounted on the upper surface of the belt 31c. The speed of the motor that rotates the two rollers 31 a and 31 b is controlled by the control device 40. Therefore, the tire 1 rolls on the belt 31c at a predetermined speed with the rotation of the belt 31c at the predetermined speed.

  Referring to FIG. 6, control device 40 includes hardware including a storage device such as a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and software mounted thereon. It is built by The control device 40 includes a calculation unit 41, a storage unit 42, a determination unit 43, and a speed control unit 44.

  The calculation unit 41 calculates an energy value in a predetermined frequency range from the force of the pattern vibration measured by the sensor 20. The predetermined frequency range is calculated as Δf by the following equation. Here, V in the following equation is a vehicle speed V (km / h) corresponding to the rolling speed of the tire 1. Dmax indicates the maximum pitch length among the above-described block pitches, and Dmin indicates the minimum pitch length. When calculating the lower limit value f1 and the upper limit value f2 of the frequency range Δf, the speed is converted to the speed per second (m / s) by multiplying the speed per hour V (km / h) by 1000/3600. The lower limit value f1 of the frequency range Δf is obtained by dividing a value obtained by converting an hourly speed V (km / h) into a second speed by a value 1.05 times the maximum pitch length Dmax. Similarly, the upper limit value f2 of the frequency range Δf is obtained by dividing a value obtained by converting the speed per hour V (km / h) to a speed per second by a value 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 a frequency range for calculating an energy value.

  A method of calculating the frequency range Δf using the above equation will be exemplified using specific numerical values. In the present embodiment, a tire 1 having a radius of 300 mm in which 34 blocks 13 are provided 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. Further, the predetermined speed V is set to 50 km / h. When these are substituted into the above equation, the lower limit f1 is 191 Hz and the upper limit f2 is 352 Hz. Therefore, the frequency range Δf is 191 to 352 Hz.

  The energy value (measured energy value) in the frequency range Δf is calculated as E by the following equation. Here, Fi in the following equation indicates a force at a certain frequency fi. 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 above numerical example, the frequency fi may be set to 191 to 352 Hz every 1 Hz.

  The storage unit 42 stores the energy value E of the new tire 1 in the same frequency range Δf calculated by the above equation from the force measured by pre-rolling at a predetermined speed V by the rolling device 30 in the reference energy value E0. It is remembered as. New refers to those that are unused or not worn.

  The determination unit 43 compares the measured energy value E measured and calculated under the same conditions for each of the parts 6 to 8 with the reference energy value E0, and if the measured energy value E is smaller than the reference energy value E0 by a predetermined amount or more. It is determined that uneven wear in the width direction has occurred, and otherwise it is determined that uneven wear in the width direction has not occurred. In the present embodiment, if the measured energy value E is equal to or less than half of the reference energy value E0, it is determined that uneven wear in the width direction has occurred. In this embodiment, since the sensor 20 is installed at a position corresponding to each of the parts 6 to 8, it can be determined whether each of the parts 6 to 8 is worn. In particular, in only one of the shoulder portion 6, the quarter portion 7, and the center portion 8, the measured energy value E is smaller than the reference energy value E0 by a predetermined amount or more (in the present embodiment, less than half), and In this case, if the measured energy value E is not smaller than the reference energy value E0 by a predetermined value or more (in the present embodiment, if it is larger than half), only the part where the measured energy value E is smaller than the reference energy value E0 by a predetermined value or more is determined. It is determined that uneven wear has occurred.

  The result of the determination by 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 the wear has occurred.

  In the present embodiment, the concept of “order” according to the tread pattern is introduced in order to determine the presence / absence of uneven wear in the width direction in more detail. Specifically, the above-described block pitch is set as a primary pitch. Then, according to the divided shape of the block 13 in the tire circumferential direction TR, the second, third, fourth, and higher orders are set. At each pitch of the order, the frequency range Δf is calculated, the measured energy value E in the frequency range Δf for each order is detected, and compared with the reference energy value E0 for each order, so that the measured energy value E is higher than the reference energy value E0. Is smaller than a predetermined value, it is determined that uneven wear in the width direction has occurred.

  More specifically, referring to FIG. 2, if the above-described block pitch (primary pitch length) is D1, a secondary pitch length D2 that is about half the primary pitch length D1, and a quarter of D1 A fourth-order pitch length D4 of about 1 is provided. Higher-order pitch lengths such as the second-order pitch length D2 and the fourth-order pitch length D4 are provided based on how many blocks 13 are divided by the lateral grooves 14 and 15 such as sipes and narrow grooves. Therefore, in the present embodiment, the frequency range Δf is similarly calculated not only for the first order but also for the second and fourth orders, the measured energy value E is detected, and the wear determination is performed by comparing the measured energy value E with the new reference energy value E0. Do. The second and subsequent frequency ranges Δf can be obtained by multiplying the first frequency range Δf by the order. That is, in the above numerical example, the first-order frequency range Δf is 191 to 352 Hz, and the second-order frequency range Δf is 382 to 704 Hz, which is twice as large, and the fourth-order frequency range Δf is four times, 764 to 1408 Hz. Becomes

FIG. 7 is a graph showing an example of the pattern vibration measured by the sensor 20 (see FIG. 3). The horizontal axis of the graph indicates time [s], and the vertical axis indicates force [N] (or acceleration [m / s ² ]). In the graph, the time when a force (or acceleration) is generated radially outward of the tire 1 is defined as a + direction. From the graph, it can be seen that large vibration occurs at the time of stepping and kicking, and substantially no vibration occurs in the contact state immediately after stepping and immediately before kicking. In the present embodiment, of such time-series data, data of a time Δt from immediately before to immediately after kicking is used. Here, the time Δt from immediately before the kicking to immediately after the kicking is a time from the occurrence of the vibration due to the kicking to the time when it calms down to a certain degree. However, data for a certain period of time immediately after the kick may be used so as not to include the peak at the time of the kick. The graph shows a substantially constant value except for the vicinity of the contact area, which indicates a centripetal force (or an acceleration generated by the centripetal force).

FIG. 8 is a graph showing an example of the pattern vibration measured by the sensor 20 (see FIG. 3). The horizontal axis of the graph indicates frequency [Hz], and the vertical axis indicates force [N] (or acceleration [m / s ² ]). The graph is obtained by viewing the data of Δt shown in FIG. 7 not by time but by frequency. The frequency of the pattern vibration corresponding to the primary pitch length D1 is about 250 Hz, the frequency of the pattern vibration corresponding to the secondary pitch length D2 is about 500 Hz, and the frequency of the pattern vibration corresponding to the quaternary pitch length D4 is about 500 Hz. It is 1000 Hz, and the peak value of the force can be confirmed at these frequencies. More specifically, the force does not increase only at each point of these frequencies, but increases with a certain width near these frequencies. This is because the pitch lengths D1, D2, and D4 of the respective orders are set with variations. Therefore, when making a wear determination, it is effective to make an energy comparison in a predetermined frequency range near the peak value, instead of comparing the force at a single frequency at the peak value. Therefore, in the present embodiment, energy comparison is performed in the frequency range Δf near the peak value of each order to determine the presence or absence of uneven wear in the width direction. 7 and 8 are illustrations for explanation, and may be different from actual ones.

  The speed control unit 44 of the present embodiment controls a motor that rotates the two rollers 31a and 31b. Therefore, the speed at which the tire 1 rolls can be controlled by the speed control unit 44, and the frequency range Δf can be adjusted. Preferably, speed V is controlled such that frequency range Δf includes the cavity resonance range of tire 1. The cavity resonance range is a frequency range in which the tire 1 causes cavity resonance. The cavity resonance is a phenomenon in which a resonance mode generated in a cavity in the tire 1 affects the support portion 32 serving as an axle. The cavity resonance occurs in a frequency range (cavity resonance range) corresponding to the shape of the tire 1 and the like, and the cavity resonance range can be specified in advance. In particular, the cavity resonance includes the resonance in the front-back direction of the tire 1 and the resonance in the up-down direction. As the speed increases, the frequencies of the two become farther apart, and the cavity resonance range increases. When the cavity resonance range is large and it is difficult for the predetermined frequency range Δf to include the cavity resonance range, the frequency range Δf and the cavity resonance range may partially overlap each other. Further, the frequency range Δf is set corresponding to a plurality of orders, but the frequency range Δf of any order may include the cavity resonance range.

  According to the method and the apparatus for determining uneven wear in the width direction of the pneumatic tire of the present embodiment, there are the following advantages.

  In the present embodiment, the sensor 20 installed at a position corresponding to at least one of the shoulder part 6, the quarter part 7, and the center part 8 in the tire width direction TW is used. Then, the presence or absence of uneven wear in the width direction is determined by measuring the force of pattern vibration generated when these portions 6 to 8 touch the ground with the sensor 20. Accordingly, it is possible to determine whether or not wear has occurred in at least one of the shoulder portion 6, the quarter portion 7, and the center portion 8. Specifically, when wear of any of the shoulder portion 6, the quarter portion 7, and the center portion 8 progresses, the vibration of the portions 6 to 8 decreases. The method according to the present embodiment compares the reference energy value E0 with the measured energy value E to detect a decrease in the vibration, thereby determining whether or not the uneven wear in the width direction has occurred. Particularly, in this determination method, the presence or absence of uneven wear in the width direction can be accurately determined because the sensors 20 are installed at positions corresponding to the determination target portions 6 to 8 (see FIG. 3).

  In the present embodiment, since the sensors 20 are respectively installed at the positions corresponding to the shoulder portion 6, the quarter portion 7, and the center portion 8, any of these portions 6 to 8 is worn. You can determine whether you are. In other words, by installing the sensor 20 for each of the parts 6 to 8, the wear state of all the parts 6 to 8 can be grasped. For this reason, it can be determined whether all the parts 6 to 8 are the entire wear in which the parts are evenly worn or whether only any one of the parts 6 to 8 is the uneven wear.

In the present embodiment, the reference energy value and the measured energy value are calculated using only data immediately before and immediately after the ejection. Therefore, clear data can be used among the measured forces. In particular, since a large vibration occurs immediately before and immediately after kicking, useful data for calculating the reference energy value and the measured energy value can be obtained. Since the tire 1 is in the ground contact state immediately after the tire 1 is stepped on and immediately before it is kicked, the force measured by the sensor 20 is:
It does not substantially vibrate (see FIG. 7). Therefore, the selection of the above data range is useful in avoiding this range.

  In the present embodiment, at the time of energy comparison, the presence or absence of uneven wear in the width direction is determined using half as a threshold value. This is because when the energy value of the pattern vibration is halved, a difference that can be felt by a general driver occurs. In addition, since the energy value is set to half the threshold value, even if the energy value to be measured is slightly changed due to the influence of disturbance such as a road surface condition, it is possible to determine whether or not uneven wear in the width direction has occurred without erroneous determination. Can be determined accurately.

  Further, in the present embodiment, the predetermined frequency range Δf can be specifically defined. In particular, the shoulder portion 6, the quarter portion 7, and the center portion 8 extending in the tire circumferential direction TR are formed with horizontal grooves extending in the tire width direction TW, so that a block having a predetermined pitch length may be formed. is there. The block 13 of the shoulder portion 6 exemplified in the present embodiment is grounded at a certain time interval as the tire 1 rotates, and generates a pattern vibration. Therefore, by adjusting the predetermined frequency range Δf for calculating the energy value to the occurrence frequency of the pattern vibration, it is possible to accurately detect uneven wear in the width direction. It should be noted here that the block pitch is designed to have a certain degree of variation (Dmin to Dmax) in order to prevent the pattern vibration from concentrating on a specific frequency. Therefore, it is effective to calculate the energy value not in one specific frequency corresponding to a specific block pitch but in a predetermined frequency range Δf corresponding to a block pitch having a variation as in the present embodiment.

  In the present embodiment, the reference energy value E0 and the measured energy value E are compared for each order of the pattern vibration, so that a more detailed determination can be made. Specifically, when one block 13 is divided in the tire circumferential direction TR by lateral grooves 14 and 15 (see FIG. 2) such as sipes and narrow grooves, pattern vibration occurs at a frequency higher than the block pitch. The high frequency pattern vibration is referred to as second, third, fourth,. For example, if a block is equally divided into two in the tire circumferential direction by a sipe, a secondary pattern vibration occurs. The secondary pattern vibration has twice the frequency of the primary pattern vibration (pattern vibration due to the block pitch). In this way, by performing the energy comparison in a more detailed unit than the block unit in consideration of the order, the uneven wear in the width direction can be evaluated in more detail.

  In the present embodiment, the speed V is controlled so that the predetermined frequency range Δf includes the cavity resonance range. Therefore, the pattern vibration can be efficiently amplified by the cavity resonance, and the force of the pattern vibration can be measured.

(2nd Embodiment)
In the present embodiment, the presence or absence of uneven wear in the width direction is determined based on the peak value of the force or acceleration measured by the sensor 20 of the pneumatic tire. The present embodiment is substantially the same as the first embodiment except that the comparison target has changed from the energy value of the first embodiment to the peak value of the present embodiment, and thus the duplicated description will be omitted. Further, similarly to the first embodiment, since the measurement target of the sensor 20 is a force, the force will be described as an example. Alternatively, when the measurement target of the sensor 20 is an acceleration, the following description of “force” may be replaced with “acceleration”.

  In the present embodiment, the storage unit 42 stores, among the forces measured by rolling the new tire 1 in advance at the predetermined speed V by the rolling device 30 from immediately before kicking to immediately after kicking (for Δt in FIG. 7). ) Is stored as the reference force F0.

  The calculation unit 41 measures the measurement force, which is the peak value of the force immediately before the kicking of the pattern vibration measured during the measurement of the tire 1 to be measured at the predetermined speed V by the rolling device 30 and immediately after the kicking (during Δt in FIG. 7). Is calculated.

  The determining unit 43 determines that uneven wear in the width direction has occurred when the measured force is smaller than the reference force by a predetermined amount or more. In this embodiment, if the measured force is less than half the reference force, it is determined that uneven wear in the width direction has occurred.

  According to the present embodiment, the occurrence of uneven wear in the width direction can be determined with high accuracy by comparing the force due to the pattern vibration at the time of kicking regardless of the frequency.

  As described above, the specific embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and can be implemented with various modifications 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. 9, the road surface section 31 may include a rotatable drum 31 d having a sufficiently large radius of curvature as compared with the tire 1.

  Alternatively, rolling device 30 may be a real vehicle.

1 Pneumatic tires (tires)
2 Wheel rim 5 Tread part 6 Shoulder part 7 Quarter part 8 Center part 11a, 11b, 11c, 11d Vertical groove 12 Horizontal groove 13 Block 14, 15 Horizontal groove 20 Sensor 30 Rolling device (automobile)
31 road surface part 31a, 31b roller 31c belt 31d drum 32 support part 40 control device 41 calculation part 42 storage part 43 judgment part 44 speed control part 50 monitor

Claims (10)

A sensor is installed on an inner surface of the pneumatic tire at a position corresponding to at least one of a shoulder portion, a quarter portion, and a center portion,
Rolling the pneumatic tire at a new speed at a predetermined speed, measuring the acceleration or force of pattern vibration generated by at least one of the shoulder portion, the quarter portion, and the center portion by the sensor,
Calculating a reference value based on the acceleration or force of the pattern vibration measured with the pneumatic tire when new,
Rolling the pneumatic tire to be measured at a predetermined speed and measuring the acceleration or force of the pattern vibration generated by the at least one of the shoulder portion, the quarter portion, and the center portion by the sensor,
Calculate a measurement value based on the acceleration or force of the pattern vibration measured on the pneumatic tire to be measured,
A method for determining uneven wear in the width direction of a pneumatic tire, comprising determining that uneven wear in the width direction has occurred when the measured value is smaller than the reference value by a predetermined value or more. The sensor is installed on the inner surface of the pneumatic tire at a position corresponding to each of the shoulder portion, the quarter portion, and the center portion,
The sensor measures the acceleration or force of the pattern vibration generated by each of the shoulder, the quarter, and the center,
In only one of the shoulder portion, the quarter portion, and the center portion, the measured value is smaller than the reference value by a predetermined value or more, and in the remaining two, the measured value is a predetermined value or more than the reference value. The method for determining uneven wear in the width direction of a pneumatic tire according to claim 1, wherein if not smaller, it is determined that only the portion where the measured value is smaller than the reference value by a predetermined amount or more is unevenly worn.   3. The pneumatic pneumatic pump according to claim 1, wherein the reference value and the measured value are calculated using only data at the time of stepping and kicking out of time-series data of acceleration or force measured by the sensor. 4. A method for determining uneven wear in the tire width direction.   The widthwise unevenness of the pneumatic tire according to any one of claims 1 to 3, wherein it is determined that uneven wear in the widthwise direction has occurred when the measured value is equal to or less than half of the reference value. How to judge wear. The reference value is a reference energy value that is an energy value calculated in a predetermined frequency range from the acceleration or force of the pattern vibration measured with the pneumatic tire when new,
5. The measurement energy value according to claim 1, wherein the measurement value is a measurement energy value that is an energy value calculated in a predetermined frequency range from acceleration or force of the pattern vibration measured by the pneumatic tire to be measured. The method for judging uneven wear in the width direction of a pneumatic tire according to any one of the preceding claims. The predetermined frequency range, using the vehicle speed V corresponding to the predetermined speed, the minimum pitch length Dmin and the maximum pitch length Dmax of the block pitch in the tire circumferential direction of the tread pattern of the pneumatic tire, The method for judging uneven wear in the width direction of a pneumatic tire according to claim 5, which is calculated as Δf by the following equation.

Assuming that the block pitch is a primary pitch, the predetermined frequency range is calculated at a pitch of each order according to the divided shape of the block in the tire circumferential direction,
Calculate the reference energy value and the measured energy value respectively in the predetermined frequency range for each order,
7. The method according to claim 6, wherein the reference energy value and the measured energy value are compared for each order, and if the measured energy value is smaller than the reference energy value by a predetermined amount or more, it is determined that uneven wear in the width direction has occurred. 3. The method for judging uneven wear in the width direction of a pneumatic tire described in 1.   The method according to any one of claims 5 to 7, wherein the predetermined speed is a speed at which the predetermined frequency range includes a cavity resonance range. The reference value is a reference acceleration or a reference force which is a peak value of an acceleration or force at the time of stepping of the pattern vibration measured at the time of a new pneumatic tire, and the time of kicking,
5. The measurement value according to claim 1, wherein the measurement value is a measurement acceleration or a measurement force which is a peak value of an acceleration or a force at the time of stepping or kicking of the pattern vibration measured by the pneumatic tire to be measured. 6. The method for judging uneven wear in the width direction of a pneumatic tire according to any one of the preceding claims. A rolling device for rolling the pneumatic tire at a predetermined speed,
A shoulder portion, a quarter portion, and a shoulder portion of the pneumatic tire which is installed on the inner surface of the pneumatic tire at a position corresponding to at least one of the center portion and is rolled by the rolling device, the quarter portion, And a sensor for measuring an acceleration or force of a pattern vibration generated by at least one of the center portions,
A storage unit that stores a reference value calculated from the acceleration or force of the pattern vibration when the pneumatic tire at the time of brand new is rolled at the predetermined speed by the rolling device,
A calculation unit that calculates a measurement value calculated from the acceleration or force of the pattern vibration measured by rolling the pneumatic tire to be measured at the predetermined speed by the rolling device,
A determining unit that determines that uneven wear in the width direction has occurred if the measured value is smaller than the reference value by a predetermined value or more.

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