JP2010181319A - Method and device for decision of tire internal fault - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine whether a tire internal fault caused by separation is generated, without having an effect on tire behavior. <P>SOLUTION: A bandpass value P which is the size of a frequency component in a frequency band of 350-390 Hz is operated from a frequency spectrum of an acceleration signal in the wheel width direction of vibration input from the road surface into a grounding surface of a tread and transmitted to a wheel from an output waveform of an acceleration sensor mounted on a spoke of the wheel. Then, the bandpass value P is compared with a threshold K set based on a bandpass value measured by mounting a normal tire and a bandpass value when traveling with a mounted tire wherein separation having a different size is generated inside the tire, to thereby determine whether an internal fault caused by separation is generated in the tire. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for detecting a failure inside a running tire.

The tire has a structure in which members such as carcass plies and belts or a metal cord coated with rubber are laminated. For this reason, when an excessive load is input to the bonded portion of the member during traveling of the vehicle, a phenomenon called socketing occurs in which the cord end portion and the coating rubber are peeled off and the rubber is cracked. When the socketing generated in each part on the tire circumference is coupled, the separation develops into a separation in which the laminated members are separated.
Further, the separation between the belts causes the both ends of the belt in the width direction to rise, and as a result, the steering stability performance may deteriorate.

By the way, when an internal failure such as separation occurs in the tire, heat generation at the failure location increases, and the temperature near the failure location increases.
Thus, a method has been proposed in which a temperature sensor is embedded in the tire shoulder portion to measure the temperature of the running tire and an internal failure of the tire is detected from this temperature change (see, for example, Patent Document 1).

  In addition, a temperature-sensitive ferrite having a Curie point in a predetermined temperature range is disposed at a predetermined pitch along the circumferential direction in the annular portion of the tire, and a magnet and an annular magnet forming an annular magnetic path intersecting the annular portion on the vehicle body side. A coil wound around the outer circumference of the road, and the electromotive force excited by the coil due to the change in magnetic flux density accompanying the rotation of the tire is measured, and the deformation of the shoulder portion of the tire is indirectly detected from this measured waveform. There has also been proposed a method of detecting abnormal distortion in an annular portion of a tire and detecting an internal failure of the tire (for example, see Patent Document 2).

There has also been proposed a method for detecting an internal failure of a tire by directly detecting deformation of a shoulder portion of the running tire.
Specifically, an acceleration sensor that measures the acceleration in the circumferential direction of the tire and an acceleration sensor that measures the acceleration in the width direction of the tire are embedded in the tire shoulder portion, and the tire circumferential portion of the running tire shoulder portion is embedded in the tire shoulder portion. After calculating the amount of deformation and the amount of deformation in the tire width direction, using these two amounts of deformation, the time series deformation of the tire shoulder is defined as the x-axis and y-axis in the tire circumferential direction and the tire width direction, respectively. Expressed as a trajectory in an orthogonal coordinate system, the size and form of deformation of the tire shoulder portion are detected from the trajectory, and an internal failure of the tire is detected (see, for example, Patent Document 3).

JP 2005-67447 A JP 2004-69462 A JP 2007-191038 A

However, in the conventional tire internal failure detection method, the sensor is embedded in the shoulder near the belt end where separation occurs, so the boundary surface between the sensor and the surrounding rubber has a new rubber crack. There is a risk of causing tire failure as a core.
In addition, when the sensor is disposed at the belt end portion where a large stress acts when the tire rolls, the belt end portion is broken and the possibility of causing separation is high.

  The present invention has been made in view of conventional problems, and it is possible to accurately determine whether or not a tire internal failure due to separation has occurred without affecting the behavior of the tire. It is an object to provide a method and apparatus.

  As a result of diligent study, the present inventor has obtained a vibration spectrum obtained by frequency analysis of the vibration in the width direction of the wheel transmitted from the tire tread to the wheel during traveling in a tire in which an internal failure due to separation has occurred. Since the magnitude of the frequency component in the frequency band of 350 Hz to 390 Hz (hereinafter referred to as the band value) is significantly reduced compared to a normal tire, if the band value is used as a separation measure, the tire The present inventors have found that the presence or absence of an internal failure can be accurately determined.

That is, the present invention is a method for determining whether or not an internal failure due to separation has occurred in a tire, the step of detecting the acceleration in the width direction of the wheel during traveling by an acceleration sensor attached to the wheel; , A step of calculating a band value that is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz of an acceleration waveform in a wheel width direction obtained from an output signal of the acceleration sensor, and the calculated band value and a measurement in advance A step of comparing a band value when the normal tire is run while being mounted on the wheel and a band value when the tire having a separation inside the tire is run while being mounted on the wheel. And determining whether an internal failure due to separation has occurred in the tire.
In addition, “separation” generally refers to a phenomenon in which the rubber and belt constituting the tire and the rubber and rubber are peeled and damaged, and the socketing phenomenon in which the cord end and the coating rubber are peeled off is also “separation”. include.

The present invention is the tire internal failure determination method, wherein the acceleration sensor is attached to a spoke of a wheel.
The invention of the present application is the tire internal failure determination method, wherein the acceleration sensor is attached to a rim flange or a rim base of a wheel rim.

The present invention is an apparatus for determining whether an internal failure due to separation has occurred in a tire, an acceleration sensor that is attached to a wheel and detects acceleration in the direction of the wheel width, and the acceleration sensor A width direction acceleration waveform extracting means for extracting a wheel width direction acceleration waveform from the output signal, and a band value for calculating a band value which is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz from the wheel width direction acceleration waveform. Based on the calculation means, and a band value when a normal tire that has been measured in advance is mounted on the wheel and a band value when a tire that has generated separation is mounted on the wheel and traveled Storage means for storing the set threshold value, the calculated band value is compared with the threshold value, and the calculated band value is compared. Value, characterized in that the internal mechanical failure due to separation in the tire when it exceeds the threshold and a and determination means has occurred.
Further, the invention of the present application is the tire internal failure determination device, characterized in that it is provided with alarm means for issuing an alarm to the driver when the determination means determines that a tire internal failure has occurred. .

  The invention of the present application is a device for determining whether or not an internal failure due to separation has occurred in a tire, an acceleration sensor attached to a wheel for detecting acceleration in the width direction of the wheel, and an output of the acceleration sensor A width direction acceleration waveform extracting means for extracting a wheel width direction acceleration waveform from the signal, and a band value calculation for calculating a band value which is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz from the wheel width direction acceleration waveform. And a plurality of tires, each of which had a separation with different size inside and a band value when a normal tire prepared in advance was mounted on the wheel. Storage means for storing a table indicating the relationship between each band value and the calculated band value and the storage means On the basis of the stored table, wherein the internal mechanical failure due to separation in the tire and a and determination means it has occurred.

According to the present invention, it is determined that a tire internal failure has occurred from the magnitude of the frequency component in the 350 Hz to 390 Hz frequency band of the acceleration waveform in the width direction of the wheel output from the acceleration sensor attached to the wheel. Thus, it is possible to determine whether or not a tire internal failure due to separation has occurred without affecting the behavior of the tire. At this time, since the threshold value used for the determination is set based on the band value measured with a normal tire mounted and the band value measured with a tire with separation inside the tire, separation is surely generated. Can be determined.
Therefore, when it is determined that a tire internal failure has occurred, if the driver is warned of this, the running stability of the vehicle can be improved.
Further, if the acceleration sensor is attached to a wheel spoke, rim flange, or rim base, the vibration of the tire tread can be detected reliably, so that the accuracy of failure determination is improved.

  In addition, a table showing in advance a relationship between a band value when running with normal tires and a band value when running with a plurality of tires having different sizes of separation inside is obtained in advance. In addition, since it is determined that an internal failure due to separation has occurred in the tire based on the calculated bandwidth value and the table, the driver can be accurately informed of the state of the tire internal failure. . Further, by comparing the table with the calculated band value, the details of the state of the tire internal failure can be understood, so that the occurrence of separation can be known at an early stage, further improving the driving safety of the vehicle. be able to.

  The summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

It is a figure which shows the structure of the tire internal failure determination apparatus which concerns on this Embodiment. It is sectional drawing which shows the structure of a tire. It is a figure which shows the generation | occurrence | production location of a separation. It is a figure which shows an example of the attachment position of an acceleration sensor. It is a figure which shows the difference in the frequency spectrum of the width direction acceleration by the presence or absence of generation | occurrence | production of a separation. It is a figure which shows the relationship between the magnitude | size of a separation, and a zone | band value. It is a flowchart which shows the tire internal failure determination method by this invention. It is a figure which shows the other structure of the tire internal failure estimation apparatus by this invention. It is a figure which shows the other example of the attachment position of an acceleration sensor.

  Hereinafter, the present invention will be described in detail through embodiments, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

FIG. 1 is a diagram showing a configuration of a tire internal failure determination device 10 according to the present embodiment.
The tire internal failure determination device 10 includes an acceleration sensor 11, an acceleration waveform extraction unit 12, a frequency analysis unit 13, a band value calculation unit 14, a failure determination unit 15, and an alarm unit 16.

FIG. 2 is a cross-sectional view showing the configuration of the tire 20.
In the figure, 21 is a bead portion, 21c is a bead core, 22 is a carcass layer, 23 is a first belt layer, 24 is a second belt layer, 25 is a tread, and 26 is an inner liner.
The carcass layer 22 is a member that forms a skeleton of the tire 20 and is provided so as to straddle a pair of bead cores 21c arranged in the bead portion 21 in a toroidal shape. Two belt layers (first and second belt layers) 23 and 24 are disposed outside the crown portion of the carcass layer 22 in the tire radial direction. The first and second belt layers 23 and 24 are each arranged such that steel cords or cords twisted with organic fibers intersect at an angle of 20 ° to 70 ° with respect to the equator direction, The first belt layer 23 disposed on the inner side in the tire radial direction is formed wider than the second belt layer 24 disposed on the outer side in the tire radial direction. The extension direction of the cord of the second belt layer 24 intersects with each other.
The socketing in which the cord end portion and the coating rubber peel and the rubber cracks mainly occurs at the end portions of the first and second belt layers 23 and 24, and when this progresses, as shown in FIG. In addition, the tire shoulder portion 27 develops into a separation in which the first belt layer 23 and the second belt layer 24 are separated.

In this example, as shown in FIGS. 4A and 4B, the acceleration sensor 11 is attached to the spoke 31s provided in the disk portion 31 of the wheel 30, and the acceleration sensor 11 is detected in the wheel width direction. The vibration which is input to the ground contact surface of the tread 25 from the road surface and propagated to the wheel 30 is detected.
The acceleration sensor 11 is preferably attached to the back side of the design surface of the spoke 31s so that pebbles or the like do not hit during traveling.

The acceleration waveform extraction unit 12 extracts a time series waveform of the wheel width direction acceleration (hereinafter referred to as a width direction acceleration waveform) from the output signal of the acceleration sensor 11.
The frequency analyzing unit 13 analyzes the frequency of the width direction acceleration waveform extracted by the acceleration waveform extracting unit 12 to obtain a frequency spectrum.

Hereinafter, the characteristics of the frequency spectrum of the acceleration in the width direction in the failed tire in which separation has occurred will be described.
In FIG. 5, test tires indicated by No. 1 to No. 5 below were respectively mounted on wheels having acceleration sensors attached to spokes, and these tires were run at 60 km / hr on a flat belt testing machine. It is a figure which shows the frequency spectrum of the wheel width direction acceleration calculated | required sometimes. The horizontal axis represents frequency (Hz), and the vertical axis represents width direction acceleration level (dB).
As for the magnitude of the failure, the size of the region where the separation between the first belt layer 23 and the second belt layer 24 shown in FIG. 3 = (width direction length W; mm) × (circumference) Directional length L; mm).
No.1 tire (thick solid line); New tire
No.2 tire (dashed line); W × L = 30 × 200
No. 3 tire (broken line); W × L = 30 × 300
No.4 tire (fine broken line); W × L = 30 × half circumference
No.5 tire (thick broken line); W x L = 30 x full circumference
The larger the number, the larger the failure.

When attention is paid to the frequency band of 350 Hz to 390 Hz in the frequency spectrum of acceleration in the wheel width direction shown in FIG. 5, it can be seen that the magnitude of the acceleration in the wheel width direction is smaller as the magnitude of the failure is larger.
FIG. 6 is a diagram illustrating the relationship between the circumferential length of the separation and the magnitude of acceleration in the wheel width direction (hereinafter referred to as a band value P) in the frequency band of 350 Hz to 390 Hz of the frequency spectrum. As can be seen from the figure, the band value P decreases as the circumferential length of the separation increases.
Therefore, it is possible to estimate how much separation has occurred in the tire by obtaining the band value P in the frequency band of 350 Hz to 390 Hz of the frequency spectrum of the acceleration in the wheel width direction.

The band value calculation means 14 calculates a band value P in the frequency band of 350 Hz to 390 Hz from the frequency spectrum obtained by the frequency analysis means 13.
Since the error tends to occur when the band value P is the width direction acceleration level at a specific frequency, the band value P is an average value of the width direction acceleration levels at a plurality of frequencies in the 350 Hz to 390 Hz band, or It is preferable to use the sum or integral value of the acceleration values in the width direction in a predetermined frequency band (for example, 370 Hz to 390 Hz) in a preset 350 Hz to 390 Hz band.

The failure determination means 15 compares the band value P calculated by the band value calculation means 14 with a preset threshold value K. If the calculated band value P is less than the threshold value K, the failure determination means 15 separates the tire. It is determined that an internal failure has occurred.
As the threshold value K for failure determination, any value between No. 1 band value P (1) and No. 5 band value P (5) in FIG. For early determination of a tire internal failure, as the threshold value K, for example, the band value P when the degree of separation is small, such as the band number P (2) of No. 2 in FIG. preferable.
The warning means 16 issues a warning to the driver by flashing a lamp or the like disposed near the driver's seat or generating a warning sound from a speaker when an internal failure occurs in the tire 20.

Next, operation | movement of the tire internal failure determination apparatus 10 by this invention is demonstrated with reference to the flowchart of FIG.
First, vibration in the width direction of the running wheel 30 is detected by the acceleration sensor 11 (step S11), and a width direction acceleration waveform that is a time-series waveform of wheel width direction acceleration is extracted from the output signal (step S12). .
Next, the frequency spectrum of the width direction acceleration waveform is analyzed to obtain a frequency spectrum (step S13), and a band value P that is the magnitude of the frequency component in the frequency band of 350 Hz to 390 Hz is calculated from the frequency spectrum (step S13). S14).
Then, the calculated band value P is compared with a preset threshold value K (step S15). If the band value P is less than the threshold value K, it is determined as “failure”, and the determination result is given to the driver. Notification is made (step S16).

  In the present embodiment, the time series of the acceleration in the wheel width direction among the vibrations input to the ground contact surface of the tread 25 from the road surface and transmitted to the wheel 30 from the output waveform of the acceleration sensor 11 attached to the spoke 31s of the wheel 30. After extracting the waveform, a band value P that is the size of the frequency component within the frequency band of 350 Hz to 390 Hz is calculated from the frequency spectrum obtained by frequency analysis of the waveform. Then, a threshold value K set based on this band value P, a band value measured with a normal tire mounted, and a band value when a tire with a separation having a different size is mounted and traveled. And whether or not an internal failure due to separation has occurred in the tire 20 is determined, so that whether or not an internal failure of the tire due to separation has occurred without affecting the behavior of the tire. Can be determined.

In the above embodiment, the threshold value K to be compared with the calculated band value P is one, but a plurality of threshold values may be provided. As a result, it is possible to warn the driver of occurrence of a tire internal failure in a plurality of stages.
Alternatively, as shown in FIG. 8, the vehicle traveled with a plurality of tires with separations of different sizes inside and a band value when a normal tire that was obtained in advance was worn and the vehicle was run. Storage means 41 for storing a table 41T showing the relationship with the current bandwidth value. Then, based on the calculated band value P and the table 41T, a failure degree estimating means 42 for estimating the magnitude of the separation generated in the tire, that is, the degree of the internal failure of the tire, is provided, so that the internal failure of the tire is detected. The degree may be estimated, and it may be determined whether or not the tire has failed according to the estimated degree of internal failure of the tire.

Specifically, as shown in FIG. 5, the degree of internal failure of the tire is set in five stages, and the estimated value of the degree of failure is replaced with a number from 1 to 5. Then, the failure degree estimation means 42 refers to the table 41T, replaces the calculated band value P with an estimated value of the degree of tire internal failure, and outputs it to the failure determination means 15.
The failure determination means 15 compares the estimated value of the estimated degree of internal failure of the tire with a preset threshold value K to determine whether an internal failure due to separation has occurred in the tire. For example, it is assumed that the threshold value K is set to 3, that is, when the separation occurs at a length of 300 mm in the tire circumferential direction, “failure” is set. When the estimated value of the degree of internal failure estimated by the failure degree estimation means 42 is 2, that is, when it is estimated that the separation has occurred over a length of 200 mm in the tire circumferential direction, the failure determination means 15 “Failure” is not determined.
On the contrary, when the threshold value K is set to 2, that is, when the separation occurs over a length of 200 mm in the tire circumferential direction as “failure”, the estimated value of the degree of internal failure estimated by the failure degree estimation means 42 Is estimated to be 3, the failure determination means 15 determines “failure”.
When the failure determination means 15 determines “failure”, the determination result is sent to the alarm means 16 to notify the driver that an internal failure has occurred in the tire.

In the above example, the band value P is obtained from the frequency spectrum of the width-direction acceleration obtained by using the frequency analysis unit 13, but a band pass filter may be used instead of the frequency analysis unit 13. Specifically, a filter for extracting a time series waveform in a frequency band of 350 Hz to 390 Hz from the time series waveform of acceleration in the tire width direction may be provided, and the RMS value of the output signal of the filter may be set to the band value P.
The frequency band for calculating the band value P may be changed according to the tire type, size, wheel speed, tire internal pressure, and the like.

  Further, the attachment location of the acceleration sensor 11 is not limited to the spoke 31s of the wheel 30, and for example, as shown in FIGS. 9A and 9B, the rim flange 32a of the rim portion 32 of the wheel 30 and the like. What is necessary is just to install in the rim base part 32b etc. in the location where the vibration of the tread 25 is easy to propagate.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the embodiment. It is apparent from the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  As described above, according to the present invention, it is possible to accurately detect the destruction inside the tire without affecting the behavior of the tire, so it is possible to detect a failure of the tire in advance and to improve the safety of the vehicle. Can be improved.

DESCRIPTION OF SYMBOLS 10 Tire internal failure determination apparatus, 11 Acceleration sensor, 12 Acceleration waveform extraction means, 13 Frequency analysis means, 14 Band value calculation means, 15 Failure determination means, 16 Alarm means,
20 tires, 21 bead parts, 21c bead cores, 22 carcass layers,
23 1st belt layer, 24 2nd belt layer, 25 tread, 26 inner liner, 27 tire shoulder part, 30 wheel, 31 disc part, 31s spoke,
32 rim part, 32a rim flange, 32b rim base part,
41 storage means, 41T table, 42 failure degree estimation means.

Claims (6)

Detecting the acceleration in the width direction of the wheel during traveling by an acceleration sensor attached to the wheel;
Calculating a band value that is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz of a wheel width direction acceleration waveform obtained from an output signal of the acceleration sensor;
The calculated band value, the band value when a normal tire that has been measured in advance is mounted on the wheel, and the tire with separation generated inside the tire when the tire is mounted on the wheel Comparing the band value with
A tire internal failure determination method, comprising: determining whether an internal failure due to separation has occurred in the tire.   The tire internal failure determination method according to claim 1, wherein the acceleration sensor is attached to a spoke of the wheel.   The tire internal failure determination method according to claim 1, wherein the acceleration sensor is attached to a rim flange or a rim base of a wheel rim. An acceleration sensor attached to the wheel and detecting acceleration in the width direction of the wheel;
A width direction acceleration waveform extracting means for extracting a wheel width direction acceleration waveform from an output signal of the acceleration sensor;
Band value calculation means for calculating a band value that is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz from the wheel width direction acceleration waveform;
It was set on the basis of a band value when a normal tire that was measured in advance was mounted on the wheel and a band value when a tire that was separated inside was driven on the wheel. Storage means for storing a threshold;
Comparing the calculated band value with the threshold value, and a determination means for determining that an internal failure due to separation has occurred in the tire when the calculated band value exceeds the threshold value A tire internal failure determination device.   The tire internal failure determination device according to claim 4, further comprising an alarm unit that issues an alarm to a driver when the determination unit determines that a tire internal failure has occurred. An acceleration sensor attached to the wheel and detecting acceleration in the width direction of the wheel;
A width direction acceleration waveform extracting means for extracting a wheel width direction acceleration waveform from an output signal of the acceleration sensor;
Band value calculation means for calculating a band value that is a magnitude of a frequency component within a frequency band of 350 Hz to 390 Hz from the wheel width direction acceleration waveform;
Each of a plurality of tires in which separations with different sizes were generated on the wheel when the normal tire prepared in advance was mounted on the wheel and each of the tires was mounted on the wheel. Storage means for storing a table indicating a relationship with the band value;
A tire internal failure determination comprising: a determination unit that determines that an internal failure due to separation has occurred in the tire based on the calculated band value and the table stored in the storage unit apparatus.

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