JP2005009953A - Method and apparatus for detecting occurrence of tire failure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting the occurrence of tire failure capable of accurately detecting the occurrence of failure of tire members before the occurrence of tire burst without error detection. <P>SOLUTION: At least either one of noises or vibration is measured when tires are rotating over a road surface. At every measurement, the amount of change or a rate of change in the result of measurement is computed based on the result of measurement acquired in a measuring process before the measurement. The amount of change or the rate of change is compared with a predetermined threshold value. The occurrence of failure in the tire members is determined in the case that the amount of change or the rate of change exceeds the threshold value. At this time, measurement on either one of the noises or vibrations is repeated within a prescribed time, for example, a time between 5 and 60 seconds to be averaged. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire for determining whether or not a failure has occurred in a component of the tire before the failure of the tire component, for example, belt edge separation occurring at the belt edge portion of the tire expands and the tire bursts. The present invention relates to a failure occurrence detection method and a tire failure occurrence detection apparatus.
[0002]
[Prior art]
Today, tire manufacturers are required to provide tires with excellent durability so that rolling tires mounted on vehicles do not burst and break during travel.
The cause of the sudden burst of the tire is, for example, that the tread member, which is a component of the tire, generates heat because the tire travels at a high speed, and as a result, the belt member, which is a component of the tire, is exposed to high heat. This is because cracks are generated at the belt edge portion of the member or at the interface between the component members, and further, separation (belt edge separation) occurs.
[0003]
On the other hand, tire manufacturers strictly control the quality of tires in order to suppress such failure of tire components. For example, by rolling a tire managed at a predetermined internal pressure on an indoor drum, increasing the rolling speed at regular time intervals, and finally determining the rolling speed when the tire bursts, durability By conducting many endurance tests to determine whether the tires are good or bad, quality control is carried out regarding the durability of the tires.
[0004]
However, the above durability test is a destructive test that bursts tires, and can only analyze tire fragments that burst and scatter, and cracks that have occurred in the tire components that cause bursts. It is difficult to accurately identify the location of failure such as separation between components and the cause of failure occurrence.
On the other hand, since the occurrence of tire bursts varies slightly from tire to tire, the endurance test in which the rolling speed is examined at regular time intervals does not reveal when the burst occurs. For this reason, it is impossible to stop the rolling immediately before the burst of the tire, and to accurately identify the location of the failure of the tire component and investigate the cause of the failure.
Therefore, there has been a problem that it cannot be reduced to the development of a tire having higher durability.
[0005]
On the other hand, as a conventional technique related to tire failure, there is a method of detecting a decrease in tire air pressure caused by some factor.
For example, Patent Document 1 below discloses a system that arranges a sound collector near a tire and searches for an abnormality in tire air pressure using sound during traveling. Further, in Patent Document 2 below, tire pattern noise during running is measured, compared with a pre-recorded frequency characteristic of tire pattern noise at the time of abnormal air pressure, and a tire that outputs an alarm signal when judged to be abnormal An air pressure abnormality detection device is disclosed.
[0006]
[Patent Document 1]
JP-A 62-198506
[Patent Document 2]
JP-A-6-199118
[0007]
[Problems to be solved by the invention]
However, the technology disclosed in these publications does not directly detect a tire failure, but detects a decrease in tire air pressure, and can detect an extreme decrease in air pressure during traveling, A slight drop in air pressure cannot be detected. On the other hand, if the air pressure is extremely lowered, the running state becomes extremely dangerous. Therefore, it is necessary to set the measurement time of the air pressure short and make an instantaneous determination. For this reason, there are many cases where an erroneous determination is made based on a noise component mixed during measurement. Further, if the threshold used when judging that the tire air pressure is abnormal is adjusted to increase the detection accuracy, there is a problem that misjudgments increase.
For this reason, the detection device that reliably detects a dangerous state in which the belt edge separation generated at the belt edge portion of the tire such as a burst of the tire expands and ruptures in a short time is warned of a decrease in air pressure. This device cannot be applied.
[0008]
Accordingly, the present invention provides a tire failure occurrence detection method and a tire failure occurrence detection device that accurately and erroneously detect the occurrence of a failure in a tire component before a tire burst occurs. For the purpose.
[0009]
[Means for Solving the Problems]
The present invention provides a measurement process for measuring at least one of noise and vibration when a tire rolls on a road surface;
A calculation step for calculating a change amount or a change rate of the measurement result based on the measurement result obtained by the measurement step before the measurement for each measurement by the measurement step;
A determination step of comparing the amount of change or rate of change with a predetermined threshold value and determining that a failure has occurred in a tire component when the amount of change or rate of change exceeds the threshold value. A tire failure detection method is provided.
[0010]
Here, it is preferable that the measurement step repeats and averages at least one measurement of noise and vibration within a predetermined time. At this time, the predetermined time is preferably 5 seconds or more and 60 seconds or less.
[0011]
For example, the measurement step measures a sound pressure level of noise in a predetermined frequency band in a frequency band of 200 to 1600 Hz, and the calculation step calculates a change amount with respect to a reference of the measured sound pressure level. In the determination step, a predetermined value within a range of 1 to 10 dB is set as a threshold value, and the measured change amount of the sound pressure level is compared with the threshold value.
[0012]
Alternatively, the measurement step measures a difference between a maximum value and a minimum value in a sound pressure waveform of noise generated by one rotation of the tire, and the calculation step calculates a change rate with respect to a reference of the measured difference. In the determination step, a predetermined value within a range of 1.15 to 3.0 is set as a threshold value, and the change rate of the difference is compared with the threshold value.
[0013]
Alternatively, the measurement step measures the difference between the maximum value and the minimum value of the vibration waveform in the tire axial force generated by one rotation of the tire, and the calculation step calculates the amount of change with respect to the reference of the measured difference. And the said discrimination | determination process makes the predetermined value in the range of 1-5% of the load concerning a tire the threshold value, and compares the measured variation | change_quantity of the said difference with the said threshold value.
[0014]
Further, the present invention provides a measuring means for measuring at least one of noise and vibration when the tire rolls on the road surface,
A calculation means for calculating a change amount or a change rate of the measurement result with reference to the measurement result obtained by the measurement means before the measurement every measurement by the measurement means;
The change amount or the change rate is compared with a predetermined threshold value, and when the change amount or the change rate exceeds the threshold value, there is a discriminating means that a failure has occurred in the constituent member of the tire. A tire failure detection device is provided.
[0015]
Here, it is preferable that the measurement unit averages by repeatedly performing at least one measurement of noise and vibration within a predetermined time. At this time, the predetermined time is preferably 5 seconds or more and 60 seconds or less.
[0016]
In the tire failure detection device, the tire is mounted on a vehicle, and the measurement unit, the calculation unit, and the determination unit are mounted on the vehicle. Alternatively, it is provided in a drum testing machine in which the tire rotates around a rotation axis and rolls on the drum.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
A tire failure detection device that implements the tire failure detection method of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.
FIG. 1 shows an example in which a tire failure detection device (hereinafter referred to as a detection device) 10, which is an example of a tire failure detection device of the present invention, is applied to an indoor durability drum test device 40.
[0018]
The indoor durable drum test apparatus 40 includes a rotating drum 42 having a drum road surface 41 that rotates the tire T in a circumferential shape, a driving motor 44 that rotationally drives the rotating drum 42 at a predetermined speed, and rotation of the driving motor 44. And a tire mounting stand 46 that can freely move in the vertical direction with respect to the drum road surface 41 of the rotary drum 42. The tire mounting stand 46 includes a mounting hub 48 that pivotally supports the rolling tire T.
[0019]
On the other hand, the detection device 10 includes a noise microphone 12, a sound level meter 14, and a processing device 16.
The noise microphone 12 is a known noise microphone that is disposed on the front end side of the drum road surface 41 of the tire T and changes the rolling noise generated between the tire T and the drum road surface 41 into an electric signal.
The sound level meter 14 is a known measuring device that uses an electrical signal sent from the noise microphone 12 as a sound pressure signal. When measuring the sound pressure, an A-characteristic filter is used.
[0020]
The processing device 18 includes a calculation unit 18, a determination unit 20, and a storage unit 22.
The calculation unit 18 samples and captures the sound pressure signal obtained by the sound level meter 16, performs a 1/3 octave band analysis to measure the sound pressure level of the noise, and is stored in the storage unit 22 for each measurement. This is a part for calculating the amount of change in the measurement result based on the measurement result obtained before this measurement.
In this case, the measurement of the sound pressure level of the noise is performed by measuring the sound pressure level of the noise in the entire frequency band of 200 to 1600 Hz, and relative to the sound pressure level of the noise in the entire frequency band of 200 to 1600 Hz measured before this measurement. The amount of change is calculated.
[0021]
The measurement of noise is performed by repeatedly performing 1/3 octave band analysis within a time period of 5 seconds to 60 seconds, and this measurement is performed intermittently. The reason why the averaging is performed repeatedly within a time period of 5 seconds or more and 60 seconds or less is to accurately detect the occurrence of cracks and separation occurring in the constituent members of the tire without making an erroneous determination, as will be described later. It is. Since it takes at least 2 minutes from the time when a tire component is cracked or peeled to the point of bursting, it accurately detects the occurrence of cracking or peeling during this period so that no error is detected. It is to do.
[0022]
The determination unit 20 uses a predetermined value within the range of 1 to 10 dB as a threshold value, compares the amount of change in the sound pressure level calculated by the calculation unit 18 with the threshold value, and if the amount of change exceeds the threshold value, This is a part that determines that a failure has occurred and generates a control signal for stopping the rotation of the rotary drum 42. The generated control signal is supplied to the control device 45.
The storage unit 22 stores a measurement result that is a reference when the calculation unit 18 compares the measurement results, and stores a threshold value when the determination unit 20 compares the amount of change in the sound pressure level. is there. The measurement result that is a reference when the measurement unit 18 compares the measurement results is the measurement result calculated by the calculation unit 18 and is a normal measurement result in which there is no crack or separation in the tire constituent member. is there. Moreover, the above-mentioned threshold value is memorize | stored in the memory | storage part 22, for example for every tread pattern or tire size, and a threshold value may be set according to the tire size or tread pattern of the tire which performs a durability test.
[0023]
A tire failure detection method when such a detection device 10 is used for the indoor durable drum test device 40 will be described.
In the endurance test performed by the indoor endurance drum test apparatus 40, a tire managed at a predetermined internal pressure is rolled on the drum road surface 41 of the endurance drum test apparatus 40 to increase the rolling speed at regular time intervals. The test will be described as an example.
FIG. 2 is a flowchart showing an example of a flow of a tire failure detection method.
[0024]
First, the drum rotation speed is set in advance so that the drum rotation speed is increased stepwise, for example, every 10 minutes from 100 km / hour to 10 km / hour.
Next, the tire T managed with a predetermined tire internal pressure is brought into contact with the drum road surface 41, a predetermined load is applied, the drum rotation speed is adjusted to, for example, 100 km / hour, and the tire T is rolled (step 100). .
In this state, noise measurement is intermittently performed. First, the first (k = 1) noise measurement is started (step 102). As described above, the noise is averaged by repeatedly performing 1/3 octave band analysis within a predetermined time period of 5 seconds to 60 seconds.
[0025]
When the measurement is the first time (k = 1) (Yes in step 104), the measurement result is stored in the storage unit 22 (step 106). The first sound pressure level is stored in the storage unit 22 as a normal measurement result in which no cracks or separation occurs in the constituent members of the tire.
Next, the second measurement (k = 2) is started (step 102).
When the measurement is the second time (k = 2) (No in Step 104), the first measurement result is called from the storage unit 22 (Step 108), and the second measurement is performed based on the first measurement result. A change amount of the result is calculated (step 110). In addition, this measurement is a measurement of the sound pressure level of the noise in the whole frequency band of 200-1600 Hz by 1/3 octave band analysis.
Next, a change amount with respect to the sound pressure level measured for the first time is calculated from the sound pressure level measured for the second time.
[0026]
Next, the determination unit 20 determines whether or not the amount of change in the sound pressure level exceeds a threshold value (step 112).
Here, the threshold value is a predetermined value within a range of 1 to 10 dB, for example, 2 dB.
[0027]
If the change amount of the sound pressure level does not exceed the threshold value (No in step 112), it is determined whether or not the drum rotation speed is a preset upper limit speed (step 114). It is determined whether or not the travel time of the drum rotation speed thus set has passed a predetermined time (step 116). Here, when the fixed time has not elapsed (in the case of No in step 116), the third measurement (k = 3) is performed (step 102).
Thus, as long as the sound pressure level does not exceed the threshold with respect to the first sound pressure level, the tire T continues to travel at the drum rotation speed adjusted in step 100 until a predetermined time in each speed step elapses.
[0028]
When a predetermined time has elapsed in step 116, the drum rotation speed is increased to the next speed step, and the drum rotation speed is adjusted (step 100). In this speed step, the first measurement (k = 1) is performed (step 102). In this manner, the sound pressure level of the tire is measured until the drum rotation speed reaches a preset upper limit speed.
At that time, if the amount of change of the sound pressure level with respect to the first sound pressure level exceeds the threshold value in step 112, it is assumed that a failure such as cracking or peeling has occurred in the tire component, and a rotation stop control signal is sent. It supplies to the control apparatus 45. As a result, the drive motor 44 stops rotating and the drum stops (step 118).
When the drum rotation speed reaches the set upper limit speed in step 114, the tire T stops the drum on the assumption that the durability in this test has passed.
[0029]
Thus, the sound pressure level obtained by the first measurement at each speed step is the normal sound pressure level, and is used as a reference for determining the amount of change in the sound pressure level.
The reason for measuring the reference sound pressure level for each speed step is that the sound pressure level changes depending on the speed. Of course, if it is known that the sound pressure level changes little with speed, it is not necessary to store the reference sound pressure level for each speed step. However, when accurately detecting the occurrence of a failure in a tire component, it is preferable to measure the sound pressure level as a reference for each speed step.
[0030]
FIG. 3 shows a normal sound pressure level at which no failure (cracking or peeling) occurs in the tire component when the sound pressure level is measured by the above-described method, and a failure occurs in the tire component. It is the figure which showed an example of the difference with the sound pressure level at the time of failure (at the time of failure occurrence).
The tire T is 205 / 65R15 92H, and the test conditions are an internal pressure of 230 (kPa), a load of 4 (kN), and a drum rotation speed of 220 (km / hour).
[0031]
According to this, the sound pressure level at the time of the failure is higher than the normal sound pressure level in the frequency band of 200 Hz to 1600 Hz, and is 4 dB in the sound pressure level (overall value) of the entire frequency band of 200 Hz to 1600 Hz. There is an increase.
Thus, since the sound pressure level changes in the frequency band of 200 Hz to 1600 Hz during normal operation and when a failure occurs, the sound pressure level of noise in a predetermined frequency band set in the frequency band of 200 to 1600 Hz is set. By measuring, obtaining the amount of change of the measured sound pressure level based on the normal sound pressure level, and comparing this amount of change with a threshold value, it is possible to accurately determine the occurrence of a tire failure. This threshold is 1 to 10 dB, preferably 2 to 4 (dB).
[0032]
For example, for a tire having the same tread pattern or the same structure as the measurement target tire shown in FIG. 3, 2 dB may be set as a threshold value for the sound pressure level in the entire frequency band of 200 Hz to 1600 Hz. Further, a threshold value may be set by investigating in advance a change in pp value immediately before a burst of a tire having the same structure and the same tread pattern.
On the other hand, depending on the frequency band, there is a region where the sound pressure level increases by about 10 dB. Therefore, when the change amount of the sound pressure level in a narrow frequency band is used for comparison with the threshold value, the threshold value may be set high. This is because if the threshold value is set low, there is a high possibility of erroneous determination due to the noise component included in the noise.
Note that the amount of change in the sound pressure level compared to the threshold is reduced by setting the frequency band wide, but since the possibility of erroneous determination by noise components is reduced, the frequency band can be set wide. preferable.
[0033]
In the above embodiment, the sound pressure level immediately before the tire T is depressed is measured, but the sound pressure level on the protruding side may be measured, and the measurement position is not particularly limited.
[0034]
In the above embodiment, the sound pressure signal obtained by the sound level meter 14 is subjected to 1/3 octave band analysis to measure the sound pressure level in a predetermined frequency band. Measures the difference between the maximum value (maximum maximum value) and the minimum value (minimum minimum value) in the sound pressure waveform (time waveform of the sound pressure level) of the rotating sound pressure signal (hereinafter, this difference is referred to as the pp value). However, it may be used for discrimination when a failure occurs. That is, the pp value measured at the first time of each speed step (k = 1) is used as a standard pp value, and the rate of change of the measured pp value with respect to the standard is obtained. This rate of change is compared with a predetermined threshold value, and if the rate of change exceeds this threshold value, it is determined that a failure has occurred in the constituent member of the tire. As this threshold value, a predetermined value within a range of 1.15 to 3 times is used.
[0035]
4 (a) and 4 (b) show examples of sound pressure waveforms of noise during normal operation and when a failure occurs. It can be seen that the sound pressure waveform at the time of failure occurrence has a larger amplitude than the sound pressure waveform at the normal time, and the above-described pp value is large. In this case, as shown in FIG. 4C, the result of time averaging the pp values of the sound pressure waveform is 184 (1.84) when a failure occurs when the normal time is 100 (1). Yes. Therefore, a change rate is obtained from the measured pp value based on the pp value measured at the first time (k = 1) of each speed step. By comparing, occurrence of a tire failure can be detected. As this threshold value, it is preferable to use the same value if the tire T has the same structure and the same tread pattern. Further, a threshold value may be set by investigating in advance a change in pp value immediately before a burst of a tire having the same structure and the same tread pattern.
[0036]
Furthermore, a microphone or a piezoelectric element may be provided in the cavity region of the tire T filled with air formed by the tire T and the wheel, and the sound pressure (noise) in the cavity region of the tire T may be measured. The measurement of the sound pressure may be the above-mentioned 1/3 octave band analysis, or the measurement of the pp value by the above-described sound pressure waveform.
As described above, since the amount of change in the sound pressure level increases in the frequency band of 200 to 1600 Hz when a failure occurs, the primary resonance frequency is generally in the range of 200 to 300 Hz, and the frequency band is higher than this resonance frequency. The cavity resonance of a tire having a higher-order resonance frequency expresses a larger resonance state when a failure occurs than when it is normal. When such a failure occurs, the sound pressure level in the tire cavity region greatly increases. Therefore, the occurrence of the failure can be effectively detected by measuring the sound pressure in the tire cavity region. In addition, since it is difficult for the disturbance to enter the sound pressure in the hollow area of the tire, the occurrence of a failure can be detected effectively and accurately.
[0037]
In any of the above embodiments, the occurrence of a tire failure is detected by measuring the noise generated in the tire T when rolling, but the axial force is measured on the mounting hub 48 of the tire T. A load cell is installed to measure the fluctuation (vibration) width of the axial force, and by comparing the amount of change in the fluctuation width of the axial force from the fluctuation width of the normal axial force with a predetermined threshold, a tire failure occurs. May be detected.
That is, the difference (pp value) between the maximum peak value and the minimum peak value of the vibration waveform in the tire axial force generated by one rotation of the tire is measured as the fluctuation range of the axial force, and the pp value at the normal time, For example, in the case of an endurance test in which the drum running speed is increased in steps, the amount of change based on the pp value obtained by the first measurement at each speed step is obtained, and 1 to 5% of the load applied to the tire. A predetermined value in the range of is used as a threshold value, and the amount of change in the measured pp value is compared with this threshold value. The variation in the axial force may be a variation in the load, a variation in the longitudinal force acting in the forward or backward direction (front-rear direction) in the drum rotation direction, or the axis of the tire rotation axis. It may be a variation in lateral force acting in the direction.
The amount of change in the pp value refers to the absolute value of the difference between the measured pp values with respect to the reference pp value.
[0038]
FIG. 5A shows a tire T having a tire size of 215 / 50ZR17 when running on a drum road surface 41 under a test condition with an internal pressure of 230 (kPa) and a load of 4.1 (kN) until it bursts. It is the graph which showed an example of the history of change of load (pp value) in tire one rotation.
[0039]
As shown in FIG. 5A, the drum rotation speed increases from 290 km / hour to 300 km / hour at the time of 1080 seconds, and the load fluctuation increases stepwise. Then, up to 1380 seconds, although the load fluctuation slightly increases, stable behavior is exhibited. However, after 1380 seconds, the load fluctuation increases, and finally the tire T bursts in 1620 seconds. From this, it can be said that a crack or peeling failure occurs in the tire component at 1380 seconds, and after this point, the crack or peeling progresses and finally bursts.
Therefore, it is possible to detect the occurrence of a failure before the burst is reached by determining an increase in load fluctuation after 1380 seconds.
[0040]
From this, the pp value obtained in the first measurement of each speed step is regarded as the fluctuation of the load at the normal time, and the amount of change in the pp value is calculated based on the pp value. By comparing the amount with the threshold value, the rolling of the tire T can be stopped immediately before the burst. The fluctuation of the load immediately before the burst is 1 to 5% of the load. Therefore, the threshold value is set to a predetermined value within the range of 1 to 5% of the load applied to the tire, for example, 3%. When the load is 4 (kN), the threshold value is 0.12 (kN).
[0041]
FIG. 5B shows a tire T having a tire size of 175 / 70R13 82Q when running on a drum road surface 41 under a test condition of an internal pressure of 200 (kPa) and a load of 3.73 (kN). It is the graph which showed an example of the log | history of the fluctuation | variation (pp value) of the load in one tire rotation.
[0042]
In FIG. 5B, the drum rotation speed increases from 180 km / hour to 190 km / hour at 1080 seconds. Immediately before 1200 seconds, the load fluctuation starts to decrease, and finally the tire T bursts at the point of 1320 seconds. Thus, when the burst is reached, the fluctuation of the load is reduced. That is, a crack or peeling failure occurs in a tire component immediately before 1200 seconds, and after this time, cracking or peeling progresses, and finally a burst occurs at 1320 seconds.
Therefore, by measuring the decrease in load variation starting just before 1200 seconds, the occurrence of a failure can be detected before the burst is reached.
From this, the pp value of the load fluctuation obtained in the first measurement at each speed step is set as the load fluctuation at the normal time, and the pp value of the load fluctuation is set based on this pp value. By calculating the amount of change and comparing this amount of change with a threshold value, the rolling of the tire T can be stopped immediately before the burst. In this case also, the threshold is preferably 1 to 5% of the load. As the threshold value, it is preferable to use the same value if the tire T has the same structure and the same tread pattern. Further, a threshold value may be set by investigating in advance a change in pp value immediately before a burst of a tire having the same structure and the same tread pattern.
[0043]
As described above, when a tire failure occurs, the load fluctuation may increase or decrease. However, the increase and decrease in the load fluctuation are caused by the phase of the uniformity component of the tire T itself and the occurrence of the failure. It is determined by the relationship with the phase of the unbalanced component that occurs according to the location of failure such as cracking or peeling. For example, if the phase of the uniformity component and the phase of the unbalance component are the same phase, the variation in load increases, and if the phase is opposite, the variation in load decreases. As described above, by using the absolute value of the difference of the measured pp value with respect to the pp value of the reference load fluctuation as the change amount of the load fluctuation, the phase and unbalance of the above-described uniformity component are used. The occurrence of a failure can be detected regardless of the relationship with the phase of the component.
[0044]
Such fluctuations in the axial force such as load may change due to sudden factors other than cracks and separation of the tire components, so averaged by measuring at least 5 seconds time average It is preferable to measure the pp value. Further, as shown in FIGS. 5A and 5B, since a burst occurs 2 to 3 minutes after the occurrence of the failure, the time average measurement is 60 seconds or less, preferably 30 seconds or less.
As described above, the measurement based on the time average of 5 seconds or more and 60 seconds or less eliminates an error in the determination of the occurrence of the failure of the tire constituent member, and the failure occurrence can be reliably detected.
In particular, among the noise generated between the tire T and the drum road surface 41, the above-described method for measuring the sound pressure level in a predetermined frequency band in the frequency band of 200 to 1600 Hz, and the pp value of the sound pressure waveform are measured. By using a combination of the above-described method and the above-described method for measuring fluctuations in axial force, it is possible to more effectively perform reliable detection without error in determining the occurrence of a failure.
[0045]
In this embodiment, the detection device 10 is applied to the indoor durable drum test device 40. However, the tire failure detection device of the present invention may be mounted on a vehicle.
[0046]
For example, as described above, the cavity resonance of a tire that occurs in a frequency band in which the primary resonance frequency is 200 to 300 Hz and the high order resonance frequency is higher than 200 to 300 Hz is not only a sound pressure but also a vibration of the tire rotation shaft. As a result, the acceleration mechanism is rigidly coupled to the suspension mechanism near the tire mounting hub, for example, the suspension arm, and the so-called unsprung vibration during driving is measured. To determine whether or not a tire has failed.
[0047]
FIG. 6 is a schematic conceptual diagram showing an example in which the tire failure detection device of the present invention is mounted on a vehicle.
In the tire failure detection device 60, an acceleration signal from an acceleration pickup 66 that is rigidly coupled and fixed to a suspension arm 64 in the vicinity of a tire mounting hub of a vehicle 62 is supplied to a processing unit 68. The processing unit 68 processes the acceleration signal, intermittently measures the vibration level of a predetermined frequency band in the frequency band of 200 to 1600 Hz, and continuously measures the pp value of the vibration waveform, For each measurement, calculate the amount of change or rate of change of the measurement result based on the normal measurement result obtained before this measurement, and compare this amount of change or rate of change with a predetermined threshold. . When this amount of change or rate of change exceeds a threshold value, it is determined that a failure has occurred in a tire component, and when it is determined that a failure has occurred, a signal is supplied to the notification device 70.
[0048]
Here, the measurement result in the normal state used as a reference when calculating the change amount or change rate is, for example, the measurement result at the time of the first measurement when a new tire is mounted on the vehicle. Such a measurement result is preferably stored as a reference for each load applied to the tire or for each traveling speed.
Further, when measuring at regular time intervals, the previous measurement result may be used as a reference. The notification device 70 uses, for example, a voice or a warning sound, or displays a warning on the display panel of the driver's seat of the vehicle 62 to indicate that a tire component has failed and the tire is immediately before the berth. Is notified. Further, the signal output from the processing unit 68 may be supplied to the drive system of the vehicle 62 so as to decelerate or stop the traveling of the vehicle.
[0049]
The processing unit 68 measures a vibration level in a predetermined frequency band in a frequency band of 200 to 1600 Hz from the supplied acceleration signal, or measures a pp value of a vibration waveform, and a degree of measurement. Then, the amount of change or rate of change of the measurement result is calculated on the basis of the measurement result obtained before this measurement, and the amount of change or rate of change is compared with a predetermined threshold value. And a processing unit 68b that determines that a failure has occurred in a constituent member of the tire when the threshold value is exceeded.
[0050]
Instead of using an acceleration signal obtained by fixing the acceleration pickup 66 to the suspension mechanism, it is provided in the vehicle 62 for another function such as a rotation signal sensor for an ABS (anti-lock braking system). You may use the acceleration signal showing the vibration obtained using a sensor, or the speed signal showing a vibration.
In addition, a piezoelectric element or a noise microphone is provided in the tire cavity area so as to measure the sound pressure of the cavity resonance generated in the cavity area of the tire surrounded by the tire and the wheel. It may be used to determine the occurrence.
Further, the sound pressure level of the noise generated between the tire mounted on the vehicle and the road surface may be measured with a noise microphone and used to determine the occurrence of the failure.
[0051]
The tire failure occurrence detection method and tire failure occurrence detection device of the present invention are not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the scope of the present invention. Of course it is good.
[0052]
【The invention's effect】
As described above in detail, according to the present invention, at least one of noise and vibration when the tire rolls on the road surface is continuously measured, and the measurement is obtained before each measurement. The amount of change or rate of change of the measurement result is calculated on the basis of the measured result, and this amount of change or rate of change is used to determine the occurrence of a failure. Therefore, before a tire burst occurs, It is less likely that the occurrence is accurately and incorrectly determined.
In particular, noise and vibration measurements are repeated within a predetermined time, for example, 5 seconds or more and 60 seconds or less, and are averaged, thereby making it possible to detect the occurrence of a failure more accurately and without error. Can be achieved.
As a result, the vehicle can be stopped before the tire bursts. In the tire endurance test, it is possible to obtain a tire in a failure occurrence state before bursting, to identify the occurrence location of cracks and peeling of the constituent members of the tire, The cause of occurrence can be analyzed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of an example of a tire failure detection device according to the present invention.
FIG. 2 is a flowchart showing a flow of an example of a tire failure detection method according to the present invention.
FIG. 3 is a diagram for explaining an example of a measurement result obtained by the tire failure detection device of the present invention.
FIGS. 4A to 4C are diagrams for explaining other examples of measurement results obtained by the tire failure detection device of the present invention. FIGS.
FIGS. 5A and 5B are diagrams for explaining another example of measurement results obtained by the tire failure detection device of the present invention. FIGS.
FIG. 6 is a schematic diagram showing the configuration of an example of a tire failure detection apparatus according to the present invention.
[Explanation of symbols]
10,60 Tire failure detection device
12 Noise microphone
14 Sound level meter
16 Processing device
18 Calculation unit
20 Discriminator
22 Memory unit
40 Indoor Drum Tester
41 Drum road surface
42 Rotating drum
44 Drive motor
46 Tire mounting stand
48 Mounting hub
62 vehicles
64 Suspension arm
66 Accelerometer
68 processing units
70 Notification device

Claims (11)

A measurement process for measuring at least one of noise and vibration when the tire rolls on the road surface;
A calculation step for calculating a change amount or a change rate of the measurement result based on the measurement result obtained by the measurement step before the measurement every time the measurement is performed by the measurement step;
A determination step of comparing the amount of change or the rate of change with a predetermined threshold and determining that a failure has occurred in a tire component when the amount of change or the rate of change exceeds the threshold. Tire failure detection method. 2. The tire failure detection method according to claim 1, wherein in the measurement step, at least one measurement of noise and vibration is repeatedly performed within a predetermined time and averaged. The tire failure detection method according to claim 2, wherein the predetermined time is a time of 5 seconds to 60 seconds. The measurement step measures a sound pressure level of noise in a predetermined frequency band of a frequency band of 200 to 1600 Hz,
The calculation step calculates a change amount of the measured sound pressure level with respect to a reference, and the determination step uses a predetermined value within a range of 1 to 10 dB as a threshold value, and calculates the change amount of the measured sound pressure level. The tire failure detection method according to any one of claims 1 to 3, which is compared with the threshold value. The measurement step measures the difference between the maximum value and the minimum value in the sound pressure waveform of the noise generated by one rotation of the tire,
The calculating step calculates a rate of change relative to the measured difference standard;
4. The tire failure occurrence according to claim 1, wherein the determining step uses a predetermined value within a range of 1.15 to 3.0 as a threshold value, and compares the change rate of the difference with the threshold value. Detection method. The measurement step measures the difference between the maximum value and the minimum value of the vibration waveform in the tire axial force generated by one rotation of the tire,
The calculation step calculates a change amount with respect to the measured difference standard,
The said discrimination | determination process makes a predetermined value within the range of 1-5% of the load concerning a tire a threshold value, and compares the measured variation | change_quantity of the said difference with the said threshold value. Tire failure detection method. Measuring means for measuring at least one of noise and vibration when the tire rolls on the road surface;
A calculation means for calculating a change amount or a change rate of the measurement result with reference to the measurement result obtained by the measurement means before the measurement every measurement by the measurement means;
The change amount or the change rate is compared with a predetermined threshold value, and when the change amount or the change rate exceeds the threshold value, there is a discriminating means that a failure has occurred in the constituent member of the tire. Tire failure detection device. The tire failure detection device according to claim 7, wherein the measurement unit repeatedly averages at least one measurement of noise and vibration within a predetermined time. The tire failure occurrence detection device according to claim 8, wherein the predetermined time is a time of 5 seconds to 60 seconds. The tire is mounted on a vehicle;
The tire failure detection device according to any one of claims 7 to 9, wherein the measurement unit, the calculation unit, and the determination unit are mounted on the vehicle. The tire failure occurrence detection device according to any one of claims 7 to 9, wherein the tire is provided in a drum testing machine that rotates about a rotation axis and rolls on a drum.

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