JP2006232036A - Tire failure detection method, tire failure detection program, and tire failure detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire failure detection method, a tire failure detection program, and a tire failure detection device, capable of suppressing erroneous operation while suppressing degradation in accuracy as a tire durability test. <P>SOLUTION: In the tire failure detection method of detecting a failure of a rotating pneumatic tire at the time of a tire durability test, an upper limit reference value L1 and a lower limit reference value L2 which are reference values on the basis of recessed/projecting portions on an outer surface of the pneumatic tire before the tire durability test or immediately after starting of the tire durability test are set (ST110). A distance L which is physical amount on the basis of the recessed/projecting portions on the outer surface of the rotating pneumatic tire is detected (ST120), and when the distance L which is the detected physical amount exceeds a range of the upper limit reference value L1 and the lower limit reference value L2 which are the reference values, counting is carried out (ST130, ST140). When a counted number N exceeds a first failure number N1, the failure of the tire is detected (ST150, ST160). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tire failure detection method, a tire failure detection program, and a tire failure detection device, and more particularly to a tire failure detection method, a tire failure detection program, and a tire failure detection device that detect a failure of a rotating pneumatic tire. It is.

  A pneumatic tire (hereinafter, simply referred to as a “tire”) is a vehicle that travels on a road surface such as a passenger car, and is in contact with the road surface and targets power from a power source such as an engine mounted on the vehicle. It is the only thing that transmits to the road surface. Therefore, the durability performance until the failure of the tire, which is the performance of the tire, greatly affects the travel limit of the vehicle. In the conventional tire endurance test, a tire failure is detected when the tire bursts. However, if the tire bursts, it will be difficult to determine the cause of the tire failure. Further, there is a possibility that the tire durability test apparatus is damaged due to the burst of the tire.

  Here, the failure of the tire is mainly considered to be a failure due to a temperature and a failure due to a mechanical problem. In the tire failure, before the tire actually bursts, the temperature of the outer surface in the vicinity of the failure location and the shape of the outer surface in the vicinity of the failure location, that is, the unevenness change. Therefore, conventionally, there has been proposed a technique for detecting a change in the unevenness of the outer surface by various methods and detecting a tire failure based on the detected change in the unevenness of the outer surface.

  For example, in the conventional example shown in Patent Document 1, a thin line is stretched along the outer edge of the tire in the meridian direction. Then, when the tire breaks down, the irregularities on the outer surface change, and the failure of the tire is detected by contacting the thin line with the changed outer surface. That is, the failure of the tire is detected based on the physical quantity based on the unevenness of the outer surface, that is, the distance between the outer surface of the rotating tire and the thin wire that behaves as a contact body. On the other hand, in the conventional example shown in Patent Document 2, the position of the outer surface of the tire is measured with a non-contact displacement meter over the entire circumference along the tire circumferential direction, and the position data of the measured outer surface before and after the tire is The amount of change is calculated by comparison at each corresponding position of, and the failure of the tire is detected when the amount of change is equal to or greater than a predetermined threshold value. In other words, a tire failure is detected when the amount of change in physical quantity based on the unevenness of the outer surface, that is, the amount of change in the distance between the outer surface of the rotating tire and the non-contact displacement meter is equal to or greater than a threshold value that is a reference value Is.

JP 2004-77464 A JP 2004-177240 A

  Here, in order to detect a tire failure before the tire bursts, it is necessary to accurately detect a change in the unevenness of the outer surface at the time of the failure. Therefore, in the technique for detecting a failure of the tire shown in Patent Documents 1 and 2, it is necessary to set the distance between the outer surface and the thin line to be short or the threshold value to be small in order to accurately detect the change in the unevenness of the outer surface. is there.

  However, the unevenness of the outer surface of the tire may change due to other than the actual failure of the tire. For example, when the rubber debris peeled off from the tread surface adheres to the outer surface of the tire due to friction with the test drum that rotates the tire, the unevenness of the outer surface is detected continuously. The irregularities may change once or several times. In this case, there is a possibility of detecting a tire failure in the technique for detecting a tire failure shown in Patent Documents 1 and 2 above. That is, there is a risk of malfunction when the tire is not broken.

  Here, in the technique for detecting a tire failure shown in Patent Documents 1 and 2, even when a tire failure is detected due to a malfunction, the rotation of the tire by the test drum is stopped. At this time, even if the tire is rotated again, the thermal history inside the tire has changed because the rotation of the tire is stopped. Therefore, even if a tire failure is detected after the tire durability test is restarted, the tire in a state where the heat history has changed has failed, and there is a possibility that the accuracy as the tire durability test may be reduced.

  Therefore, the present invention has been made in view of the above, and a tire failure detection method, a tire failure detection program, and a tire failure that can suppress malfunction while suppressing a decrease in accuracy as a tire durability test. An object is to provide a detection device.

  In order to solve the above-described problems and achieve the object, the present invention provides a tire failure detection method for detecting a failure of a rotating pneumatic tire during a tire durability test, before the tire durability test or immediately after the start of the tire durability test. A reference value setting procedure for setting a reference value based on irregularities on the outer surface of the pneumatic tire, a physical quantity detection procedure for detecting a physical quantity based on irregularities on the outer surface of the rotating pneumatic tire, and the detected physical quantity Alternatively, it includes a counter procedure that counts when the detected change amount of the physical quantity exceeds the reference value, and a failure detection procedure that detects a tire failure when the counted number exceeds the first failure count. And

  According to the present invention, in the tire failure detection method, the physical quantity is at least one of distance, speed, acceleration, and load.

  In the present invention, in the tire failure detection method, the outer surface is an outer surface of a sidewall portion of the pneumatic tire.

  Further, according to the present invention, in the tire failure detection device for detecting a failure of a rotating pneumatic tire at the time of a tire durability test, based on the unevenness of the outer surface of the pneumatic tire before the tire durability test or immediately after the start of the tire durability test. A reference value setting means for setting a reference value, a physical quantity detection means for detecting a physical quantity based on irregularities on the outer surface of the rotating pneumatic tire, and the detected physical quantity or a change amount of the detected physical quantity is the reference Counter means for counting when a value is exceeded, and failure detecting means for detecting a tire failure when the counted number exceeds the first number of failures.

  In the tire failure detection apparatus according to the present invention, the physical quantity detection means includes at least one of a distance meter, a speedometer, an acceleration watch, and a load cell.

  In the tire failure detection apparatus according to the present invention, the outer surface is an outer surface of a sidewall portion of the pneumatic tire.

  According to these inventions, the physical quantity based on the unevenness of the outer surface of the detected rotating pneumatic tire or the amount of change of the detected physical quantity is the pneumatic before the set tire endurance test or immediately after the start of the tire endurance test. Counting is performed every time the reference value based on the unevenness of the outer surface of the tire is exceeded. When the counted number exceeds the first number of failures, a tire failure is detected. Here, the change in the unevenness of the outer surface due to the failure of the tire is constant or increases according to the rotation of the tire. That is, in the case of a tire failure, the physical quantity based on the unevenness of the outer surface continuously exceeds the reference value every time the pneumatic tire makes one revolution. Therefore, when the detected physical quantity or the detected change in the physical quantity exceeds the set reference value for the first failure count, it can be determined that the irregularities on the outer surface have changed due to a tire failure. Thereby, malfunction can be suppressed, suppressing the fall of the precision as a tire durability test.

  According to the present invention, in the tire failure detection method, a count interval measurement procedure for measuring the time interval of the count, and a count for clearing the count when the measured time interval of the count exceeds a predetermined clear time And a clearing procedure.

  According to the present invention, in the tire failure detection device, the count interval measuring means for measuring the time interval of the count, and the count for clearing the count when the measured time interval of the count exceeds a predetermined clear time And a clearing means.

  According to these inventions, when the count time interval exceeds a predetermined clear time, that is, when the detected physical quantity or the detected change in the physical quantity does not continuously exceed the reference value, the count is cleared. . Therefore, this count is cleared when counted by a change other than a change in the irregularities of the outer surface due to a tire failure. That is, it is counted only when the unevenness of the outer surface due to a tire failure changes continuously. Thereby, malfunction can be further suppressed, suppressing the fall of the precision as a tire durability test.

  According to the present invention, in the tire failure detection method, the failure detection procedure may be performed when the number of times that the measured count time interval is less than the time for which the pneumatic tire makes one rotation exceeds a second failure count. It is characterized by detecting a failure.

  According to the present invention, in the tire failure detection device, the failure detection means is configured such that the number of times that the time interval of the measured count is less than the time for which the pneumatic tire makes one revolution exceeds a second failure count. It is characterized by detecting a failure.

  Here, in the pneumatic tire, there is a pneumatic tire in which the physical quantity based on the unevenness of the outer surface or the amount of change of the physical quantity already exceeds the reference value when the tire durability test is performed. In this case, the number of times counted when the detected physical quantity or the amount of change in the detected physical quantity exceeds the reference value may be the first number of failures before a tire failure occurs. The count performed when the detected physical quantity or the change amount of the detected physical quantity exceeds the reference value before the failure of the tire is performed only once during one rotation of the pneumatic tire. Become. That is, before a tire failure occurs, the time interval for counting is the time for one turn of the pneumatic tire. According to these inventions, when the time interval of the count is less than the time for one rotation of the pneumatic tire, that is, during the one rotation of the pneumatic tire, the detected physical quantity or the change amount of the detected physical quantity is the reference. When the value exceeds two times, if this number exceeds the second failure number, a tire failure is detected. Thereby, even if the physical quantity based on the unevenness of the outer surface of the pneumatic tire or the amount of change of the physical quantity exceeds the reference value before the failure, the tire failure can be detected.

  According to the present invention, in the tire failure detection method, the physical quantity detection procedure is characterized in that the physical quantity is detected by a contact body that contacts the outer surface and behaves according to the unevenness.

  According to the present invention, in the tire failure detection device, the physical quantity detection means detects the physical quantity with a contact body that contacts the outer surface and behaves according to the unevenness.

  According to these inventions, the physical quantity is detected using the contact body that contacts the outer surface and behaves according to the unevenness of the outer surface. Therefore, it is possible to detect a physical quantity based on the unevenness of the outer surface of the portion that contacts the contact body. Thereby, the failure in the wide range of a pneumatic tire is detectable in one tire endurance test.

  Further, the present invention is characterized in that a computer executes the tire failure detection method. According to the present invention, by causing the computer to read and execute the program, the tire failure detection method can be realized using the computer, and the same effects as those of these methods can be obtained.

  According to the tire failure detection method, the tire failure detection program, and the tire failure detection device according to the present invention, there is an effect that malfunction can be suppressed while suppressing a decrease in accuracy as a tire durability test.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. In the following embodiments, a case where a drum type tire durability test apparatus is used will be described. However, a flat panel type or flat belt type tire test apparatus may be used.

  FIG. 1 is a diagram illustrating a configuration example of a tire durability test apparatus including a tire failure detection apparatus that executes the tire failure detection method according to the first embodiment. As shown in FIG. 1, a tire durability test apparatus 1-1 according to the first embodiment includes a test drum 2, a tire 3 as a test target, a support device 4 that rotatably supports the tire 3, and a tire 3. A physical quantity detection device 5 that detects a physical quantity based on the unevenness of the outer surface and a control device 6-1 that controls the tire durability test device 1-1 and functions as a tire failure detection device that detects a failure of the tire 3. It is configured.

  The test drum 2 is rotatably supported by a drum rotation shaft (not shown) and is rotated by a drive source (not shown). The test drum 2 can freely adjust its rotation speed by a drum rotation speed signal output from the control device 6-1. Here, the test drum 2 in the tire durability test is in contact with the outer surface which is the surface of the tire 3 in the tread portion 31 of the tire 3. Therefore, when the test drum 2 is rotated by the drive source, the tire 3 rotates with respect to the support device 4 due to friction with the test drum 2. That is, the test drum 2 has a function as a road surface when the tire 3 is mounted on the vehicle.

  The tire 3 is a test target in a tire durability test, and includes a tread portion 31, a sidewall portion 32, and a tire bead portion 33. The tire 3 is assembled to the rim 70 by fitting the tire bead portion 33 to the flange portion 71 of the rim 7. Since the rim 70 is rotatably supported by the support device 4, the tire 3 is rotatably supported by the support device 4.

  The support device 4 can move in a direction toward and away from the test drum 2 as indicated by an arrow A shown in the figure by a load signal output from the control device 6-1. That is, the load applied to the tire 3 can be adjusted by the support device 4 moving in the arrow A direction. Further, the support device 4 rotates the tire 3 with respect to the test drum 2 as shown by an arrow B by the slip angle signal output from the control device 6-1, so that the tire with respect to the rotation direction of the test drum 2 is obtained. 3, that is, the slip angle of the tire 3 can be adjusted. Further, by rotating the tire 3 relative to the test drum 2 as indicated by an arrow C by the camber angle signal output from the control device 6-1, the angle of the tire 3 with respect to the radial direction of the test drum 2 is adjusted. That is, the camber angle of the tire 3 can be adjusted.

  The physical quantity detection device 5 is a physical quantity detection unit, and is fixed to the support device 4. The physical quantity detection device 5 includes a contact body 51 and a displacement meter 52. The contact body 51 has a cylindrical shape, and is rotatably supported with respect to the support device 4 via an elastic member 53. An elastic member 53 is disposed between the contact body 51 and the support device 4. One end portion of the elastic member 53 is fixed to the support device 4, and the other end portion rotatably supports the contact body 51. The elastic member 53 biases the contact body 51 in a direction in which the contact body 51 comes into contact with the tire 3. Therefore, the contact body 51 rotates in accordance with the rotation of the tire 3 by the test drum 2 in a state where the contact body 51 is always in contact with the outer surface of the sidewall portion 32 of the tire 3 in the tire durability test. Thereby, this contact body 51 behaves according to the unevenness | corrugation of the outer surface (outer surface in the side wall part 31) of the tire 3 to rotate. Here, since the contact body 51 has a cylindrical shape, the contact body 51 is in line contact or surface contact with the outer surface of the tire 3. Therefore, when the tire 3 rotates, the contact body 51 comes into contact with a wide range of outer surfaces in the circumferential direction of the tire 3 and behaves according to the unevenness of the wide range of outer surfaces. Thereby, the distance which is a physical quantity is detectable as mentioned later based on the unevenness | corrugation of the outer surface of the tire 3 of the part which the contact body 51 contacts. Thereby, a failure in a wide range of the tire 3 can be detected in one tire durability test.

  The displacement meter 52 is a non-contact displacement meter, such as a laser displacement sensor. The displacement meter 52 is attached to the support device side of the elastic member 53 in the physical quantity detection device 5, irradiates the contact body 51 with a laser as indicated by an arrow D, and reaches the contact body 51 based on the reflected light. The distance L is measured. In other words, the displacement form 52 detects the distance L, which is a physical quantity based on the unevenness of the outer surface of the tire 3. The distance L measured by the displacement meter 52, that is, the detected distance L is output to the control device 6-1.

  The control device 6-1 inputs and outputs an input signal such as a distance signal based on the distance L detected by the displacement meter 52 of the physical quantity detection device 5 and an output signal such as a rotation speed signal, a load signal, and a slip angle signal. An input / output port (I / O) 61, a processing unit 62, a counter unit 63, and a storage unit 64 are included. An input / output device 8 is connected to the control device 6-1, and an input means 81 provided therein is connected to an input / output port 61. The size of the tire 3, the air pressure of the tire 3, and the test Data based on durability test conditions such as the rotational speed of the drum 2, the load applied to the tire 3, the slip angle of the tire 3, and other data are also given to the control device 6-1. The control device 6-1 controls the rotational speed of the test drum 2, controls the load on the tire 3, and the slip angle of the tire 3 with respect to the test drum 2 based on the data based on the given durability test conditions and other data. This tire durability test apparatus 1-1 is controlled by performing the above control. Note that an input device such as a keyboard, a mouse, and a microphone can be used as the input means 71.

  The processing unit 62 includes a memory such as a RAM and a ROM, and a CPU (Central Processing Unit). The processing unit 62 includes at least a physical quantity acquisition unit 65 that acquires a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 detected by the physical quantity detection device 5, and a reference value based on the unevenness of the outer surface of the tire 3. A reference value reference value setting unit 66 that is a reference value setting unit to be set, and a failure detection unit 67 that is a failure detection unit that detects a tire failure. When detecting the failure of the tire 3 by the control device 6-1 that is a tire failure detection device, the processing unit 62 uses the tire signal based on the distance signal input to the control device 6-1 as described above. The failure detection program is read into a memory (not shown) of the processing unit 62 and calculation is performed. Note that the processing unit 62 appropriately stores a numerical value in the middle of the calculation in the storage unit 63 and appropriately calculates the stored numerical value from the storage unit 63 to perform the calculation. The processing unit 62 may be realized by dedicated hardware instead of the tire failure detection program.

  Various data at the time of failure of the tire 3 such as the failure of the tire 3 detected by the processing unit 62, the time until the failure, the rotation speed of the test drum 2 at the time of the failure, the load of the tire 3 and the slip angle. Are displayed by the display means 72 of the input / output device 7. Here, a CRT (Cathode Ray Tube), a liquid crystal display device, or the like can be used as the display means 72. Further, various data at the time of failure of the tire 3 can be output to a printer (not shown). The storage unit 63 may be provided in the processing unit 62, or may be provided in another device (for example, a database server). Moreover, the structure which can access the control apparatus 6-1 by either a wired or wireless method from the terminal device which is not shown provided with the input / output device 7 may be sufficient.

  The storage unit 63 stores a tire failure detection program in which the tire failure detection method according to the present invention for realizing the tire failure detection method according to the present invention is incorporated. Here, the storage unit 63 is a fixed disk device such as a hard disk device, a flexible disk, a magneto-optical disk device, or a non-volatile memory such as a flash memory (a storage medium that can only be read such as a CD-ROM), It can be constituted by storage means such as a volatile memory such as RAM (Random Access Memory), or a combination thereof. The counter unit 64 is a counter unit that receives a counter signal and a clear signal output from the processing unit 62 and performs counting or clears the count.

  Further, the tire failure detection program is not necessarily limited to a single configuration, but cooperates with a program already stored in a computer system, for example, a separate program represented by an OS (Operating System). The function may be achieved. Further, a tire failure detection program for realizing the function of the processing unit 62 shown in FIG. 1 is stored in a computer-readable recording medium, and the tire failure detection program recorded on the recording medium is read into a computer system. The tire failure detection method according to the present invention may be executed by executing the method. The “computer system” here includes an OS and hardware such as peripheral devices.

  Next, a tire failure detection method according to the first embodiment will be described. Here, this tire failure detection method detects a failure of the rotating tire 3 in the tire durability test. The tire endurance test is performed based on the endurance test conditions, and may be performed without changing the endurance test conditions, or may be performed by changing at least one of the endurance test conditions.

  FIG. 2 is a flowchart of the tire failure detection method according to the first embodiment. FIG. 3 is a flowchart of the reference value setting method. FIG. 4 is an explanatory diagram of the reference value setting method. FIG. 5 is a diagram showing a change in irregularities on the outer surface of the tire. First, in the tire failure detection method according to the first embodiment, as illustrated in FIG. 2, the reference value setting unit 66 of the processing unit 62 of the control device 6-1 has the upper reference value L <b> 1 and the lower reference value L <b> 2 as reference values. Setting is performed (step ST110). The upper limit reference value L1 and the lower limit reference value L2 are performed before the tire durability test (for example, during preliminary running) or immediately after the start of the tire durability test. This is for acquiring the state of the unevenness of the outer surface before failure occurs in the tire 3 and the unevenness of the outer surface of the tire 3 changes.

  Specifically, as shown in FIG. 3, the reference value setting method is such that the physical quantity acquisition unit 65 of the processing unit 62 of the control device 6-1 rotates the air before the tire endurance test or immediately after the start of the tire endurance test. The distance L which is a physical quantity based on the unevenness of the outer surface of the entering tire 3 is acquired (step ST111). The physical quantity acquisition unit 65 acquires the distance L detected by the physical quantity detection device 5 and output to the control device 6-1 in a state where the tire 3 is rotating. That is, the physical quantity acquisition unit 65 acquires the distance L to the contact body 51 that behaves according to the unevenness of the outer surface of the rotating tire 3 detected by the displacement meter 52. The acquired distance L, which is a physical quantity, is stored in the storage unit 63 as appropriate.

  Next, the reference value setting unit 66 of the processing unit 62 determines whether or not the tire 3 has made one or more revolutions (step ST112). That is, the reference value setting unit 66 determines whether or not the distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 for at least one round of the tire 3 has been acquired. Therefore, if the reference value setting unit 66 determines that the tire 3 has not made one or more revolutions, the reference value setting unit 66 repeats step ST111 until the tire 3 has made one or more revolutions, and acquires the distance L for one round of the tire 3. The rotation speed of the tire 3 may be obtained by calculating from the rotation speed of the test drum 2 and the size of the tire 3, or a base point sensor that detects a base point is provided on the outer surface of the tire 3. It may be obtained by detecting the base point of the outer surface of the rotating tire 3 by this base point sensor.

Next, when determining that the tire 3 has made one or more revolutions, the reference value setting unit 66 of the processing unit 62 calculates a difference P1 between the maximum value L _MAX and the minimum value L _MIN of the distance L (step ST113). Here, the relationship between the distance L, which is a physical quantity to be acquired, and the number of rotations of the tire 3 has a waveform as shown in E of FIG. 4 because the outer surface of the tire 3 is formed with irregularities instead of a flat surface. . Therefore, the reference value setting unit 62, the determined maximum value L _MAX and the minimum value L _MIN, which is the difference between the maximum value L _MAX and the minimum value L _MIN P1 in one round of the tire 3 of the waveform E calculate.

Next, as shown in FIG. 3, the reference value setting unit 66 of the processing unit 62 calculates P2 from the following equation (1) (step ST114). That is, P2 is calculated by multiplying P1 by the correction coefficient K1. Here, the correction coefficient K1 is preferably 1.01 to 5.00, and more preferably 1.10 to 2.00.
P2 = P1 × K1 (1)

Next, the reference value setting unit 66 of the processing unit 62 calculates the upper limit reference value L1 and the lower limit reference value L2 from the following formulas (2) and (3) (step ST115). Here, P1 which is the difference between the maximum value L _MAX and the minimum value L _MIN multiplied by the correction coefficient K1 and half of the difference between P1 and P1 are added to the maximum value L _MAX and the minimum value L _MIN respectively. The upper limit reference value L1 and the lower limit reference value L2 shown in FIG. 4 are calculated.
L1 = L _MAX + (P2-P1) / 2 (2)
L2 = L _MIN − (P2−P1) / 2 (3)

  Next, as shown in FIG. 2, when the tire durability test is started, the physical quantity acquisition unit 65 of the processing unit 62 acquires a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 (step ST120). . That is, the physical quantity acquisition unit 65 sets the physical quantity detection device 5 in a state where the tire 3 is rotated after the upper limit reference value L1 and the lower limit reference value L2 are set as reference values by the reference value setting unit 66. The distance L detected and output to the control device 6-1 is acquired.

  Next, the failure detection unit 67 of the processing unit 62 determines whether the distance L detected and acquired by the physical quantity detection device 5 is not more than the upper limit reference value L1 and not less than the lower limit reference value L2 ( Step ST130). That is, it is determined whether or not the distance L, which is a physical quantity based on the unevenness of the outer surface of the tire, exceeds the range between the upper limit reference value L1 and the lower limit reference value L2, which are reference values. When it is determined that the distance L acquired by the failure detection unit 67 is not more than the upper limit reference value L1 and not less than the lower limit reference value L2, the physical quantity detection device 5 continues to detect the distance L that is a physical quantity. Therefore, since the physical quantity acquisition unit 65 continues to acquire the distance L, a waveform of the distance L corresponding to the number of rotations of the tire 3 is formed as shown in F of FIG. Here, when a failure of the tire 3 occurs, the outer surface near the failure portion starts to bulge. That is, when the failure of the tire 3 occurs, the unevenness of the outer surface changes, and the distance L changes. As shown in the figure, the distance L corresponding to the outer surface in the vicinity of the failure location out of the continuously acquired distance L exceeds L1.

Next, the counter unit 63 of the control device 6-1 counts when it is determined that the distance L acquired by the failure detection unit 67 of the processing unit 62 exceeds the upper limit reference value L1 or less than the lower limit reference value L2. It performs (step ST140). That is, the counter unit 63 counts when the distance L, which is the physical quantity detected by the physical quantity detection device 5 and acquired by the physical quantity acquisition unit 65, exceeds the range between the upper limit reference value L1 and the lower limit reference value L2, which are reference values. Do. Specifically, the count is performed by the following equation (4).
N = N + 1 (4)

  Next, the failure detection unit 67 of the processing unit 62 determines whether or not the number of times N counted by the counter unit 63 exceeds the first number of failures N1 (step ST150). When the failure of the tire 3 occurs, as described above, the outer surface in the vicinity of the failure portion starts to expand, continues to expand to a certain extent, and the tire 3 bursts. Therefore, the change in the unevenness of the outer surface due to the failure of the tire 3 is constant or increases corresponding to the number of rotations of the tire. Thereby, when the tire 3 fails, the distance L acquired by the failure detection unit 67 of the processing unit 62 continuously exceeds the upper limit reference value L1 every time the tire 3 makes one rotation. Here, the number of first failures N1 is preferably 2 or more, and more preferably 5 to 20 times.

  Next, when it is determined that the number of times N counted by the counter unit 63 by the failure detection unit 67 of the processing unit 62 does not exceed the first number of failures N1, the physical quantity acquisition unit 65 of the processing unit 62 further acquires the distance L. to continue. When the counter unit 63 determines that the distance L acquired by the failure detection unit 67 exceeds the upper limit reference value L1 or less than the lower limit reference value L2, the counter unit 63 continues to count. That is, step ST120 to step ST150 are repeated.

  Next, the failure detection unit 67 of the processing unit 62 detects a failure of the tire 3 when determining that the number of times N counted by the counter unit 63 exceeds the first number of failures N1 (step ST160). The control device 6-1 stops the rotation of the test drum 2 when the failure detection unit 67 detects a failure of the tire 3. Therefore, the rotation of the tire 3 can be stopped before the failure of the tire 3 proceeds. Thereby, the burst of the tire 3 can be suppressed. When the failure detection unit 67 detects a failure of the tire 3, the control device 6-1 may cause the display means 82 to display the endurance test condition where the tire 3 has failed, or generate an alarm. You may do it.

  As described above, the distance L, which is a physical quantity based on the unevenness of the outer surface of the rotating tire 3 in the detected tire endurance test, is the set value of the outer surface of the tire 3 before the tire endurance test or immediately after the start of the tire endurance test. Counting is performed every time the range between the upper limit reference value L1 and the lower limit reference value L2, which is a reference value based on the unevenness, is exceeded. When the counted number exceeds the first failure count N1, a tire failure is detected. Therefore, when the detected physical quantity exceeds the set reference value by the first failure count N1, it can be determined that the unevenness of the outer surface has changed due to the failure of the tire 3. Thereby, malfunction can be suppressed, suppressing the fall of the precision as a tire durability test.

In the first embodiment, the upper limit reference value L1 and the lower limit reference value L2 are calculated as the reference values based on P1, which is the difference between the maximum value L _MAX and the minimum value L _MIN for one lap of the tire 3. However, the present invention is not limited to this. FIG. 6 is a flowchart of the tire failure detection method according to a modification of the first embodiment. FIG. 7 is a flowchart of the reference value setting method according to the modification of the first embodiment. The tire failure detection method according to the modification of the first embodiment shown in FIGS. 6 and 7 has the same basic configuration as the tire failure detection method according to the first embodiment shown in FIGS. The explanation will be simplified.

  First, as shown in FIG. 6, in the tire failure detection method according to the modification of the first embodiment, the reference value setting unit 66 of the processing unit 62 of the control device 6-1 is an upper reference value L3 and a lower reference. The value L4 is set (step ST170). Specifically, as shown in FIG. 7, first, the physical quantity acquisition unit 65 is a distance that is a physical quantity based on the unevenness of the outer surface of the rotating pneumatic tire 3 before the tire durability test or immediately after the start of the tire durability test. L is acquired (step ST171). Next, the reference value setting unit 66 of the processing unit 62 determines whether or not the tire 3 has made one or more revolutions (step ST172).

Next, when the reference value setting unit 66 of the processing unit 62 determines that the tire 3 has made one revolution or more, the maximum value L _MAX of the distance L, the minimum value L _MIN , and the intermediate value between the maximum value L _MAX and the minimum value L _MIN. L _MID is determined (step ST173). Next, the reference value setting unit 66 of the processing unit 62 calculates the upper limit reference value L3 and the lower limit reference value L4 from the following equations (5) and (6) (step ST174). Here, the upper limit reference value L3 and the lower limit reference value L4 are calculated by multiplying the respective values obtained by subtracting the intermediate value L _MID from the maximum value L _MAX and the minimum value L _MIN by the correction coefficient K1.
L3 = K1 (L _MAX -L _MID ) (5)
L4 = K1 (L _MIN −L _MID ) (6)

Next, as shown in FIG. 6, when the tire durability test is started, the physical quantity acquisition unit 65 of the processing unit 62 acquires a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 (step ST120). . Next, the failure detection unit 67 of the processing unit 62 has a value obtained by subtracting the intermediate value L _MID from the acquired distance L detected by the physical quantity detection device 5 is equal to or less than the upper limit reference value L3 and equal to or greater than the lower limit reference value L4. Is determined (step ST180). That is, whether or not the value obtained by subtracting the intermediate value L _MID from the distance L, which is the change amount of the physical quantity based on the unevenness of the outer surface of the tire, exceeds the range between the upper limit reference value L3 and the lower limit reference value L4 that are reference values. Determine whether.

Next, when it is determined that the value obtained by subtracting the intermediate value L _MID from the distance L acquired by the failure detection unit 67 of the processing unit 62 is not more than the upper limit reference value L1 and not less than the lower limit reference value L2, the physical quantity detection device The distance L where 5 is a physical quantity is continuously detected. Next, the counter unit 63 of the control device 6-1 has a value obtained by subtracting the intermediate value L _MID from the distance L acquired by the failure detection unit 67 of the processing unit 62 exceeds the upper limit reference value L3 or less than the lower limit reference value L4. Is determined (step ST140). Next, the failure detection unit 67 of the processing unit 62 determines whether or not the number of times N counted by the counter unit 63 exceeds the first number of failures N1 (step ST150).

  Next, when it is determined that the number of times N counted by the counter unit 63 by the failure detection unit 67 of the processing unit 62 does not exceed the first number of failures N1, the number of times N counted by the counter unit 63 is the first number of failures N1. Step ST120, Step ST180, Step ST140, and Step ST150 are repeated until the value exceeds. Next, the failure detection unit 67 of the processing unit 62 detects a failure of the tire 3 when determining that the number of times N counted by the counter unit 63 exceeds the first number of failures N1 (step ST160).

As described above, a value obtained by subtracting the intermediate value L _MID from the distance L, which is a change amount of the physical quantity based on the unevenness of the outer surface of the rotating tire 3 in the detected tire durability test, is set before the set tire durability test or This is counted every time the range between the upper limit reference value L3 and the lower limit reference value L4, which is a reference value based on the unevenness of the outer surface of the tire 3 immediately after the start of the tire durability test, is exceeded, and this counted number is the first failure count. When N1 is exceeded, a tire failure is detected. Therefore, when the detected physical quantity exceeds the set reference value by the first failure count N1, it can be determined that the unevenness of the outer surface has changed due to the failure of the tire 3. Thereby, malfunction can be suppressed, suppressing the fall of the precision as a tire durability test.

  FIG. 8 is a diagram illustrating a configuration example of a tire durability test apparatus including a tire failure detection apparatus that executes the tire failure detection method according to the present invention. The tire durability test apparatus 1-2 according to Example 2 shown in FIG. 8 is different from the tire durability test apparatus 1-1 according to Example 1 shown in FIG. 1 in that the processing unit 62 of the control device 6-2 counts. This is a point that further includes an interval measurement unit 68 and a count clear unit 69. The basic configuration of the tire durability test apparatus 1-2 according to the second embodiment is substantially the same as the basic configuration of the tire durability test apparatus 1-1 according to the first embodiment, and the description thereof is omitted.

  In addition to the physical quantity acquisition unit 65, the reference value setting unit 66, and the failure detection unit 67, the control device 6-2 includes a count interval measurement unit 68 that is a count interval measurement unit that measures a time interval of the count, and a counter unit 64. And a count clear unit 69 for clearing the count.

  Next, a tire failure detection method according to Example 2 will be described. FIG. 9 is a flowchart of the tire failure detection method according to the second embodiment. The tire failure detection method according to the second embodiment shown in FIG. 9 has the same basic configuration as the tire failure detection method according to the first embodiment shown in FIG. 2 and FIG. . Further, the reference value setting method in the tire failure detection method according to the second embodiment shown in FIG. 9 is the same as the reference value setting method shown in FIG.

  First, in the tire failure detection method according to the second embodiment, as illustrated in FIG. 9, the reference value setting unit 66 of the processing unit 62 of the control device 6-2 has the upper reference value L1 and the lower reference value L2 as reference values. Setting is performed (step ST210).

  Next, when the tire durability test is started, the physical quantity acquisition unit 65 of the processing unit 62 acquires a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 (step ST220).

  Next, the failure detection unit 67 of the processing unit 62 determines whether the distance L detected and acquired by the physical quantity detection device 5 is not more than the upper limit reference value L1 and not less than the lower limit reference value L2 ( Step ST230).

  Next, when the counter unit 63 of the control device 6-2 determines that the distance L acquired by the failure detection unit 67 of the processing unit 62 exceeds the upper limit reference value L1 or less than the lower limit reference value L2, the count is counted. It performs (step ST240).

  Next, the count interval measurement unit 68 of the processing unit 62 measures the count time interval T (step ST250). The counting time interval T is a time from the counting by the counter unit 64 to the next counting, that is, the counting interval. The count interval measurement unit 68 starts measuring the count time interval T after the counter unit 64 first counts.

  Next, the count clear unit 69 of the processing unit 62 determines whether or not the measured count time interval T exceeds a predetermined clear time T1 (step ST260). As described above, when the failure of the tire 3 occurs, the change in the unevenness of the outer surface due to the failure of the tire 3 is constant or increases corresponding to the number of rotations of the tire. However, some changes in the unevenness of the outer surface of the tire 3 may not be caused by a failure of the tire 3, and in this case, the distance L acquired by the failure detection unit 67 may exceed the upper limit reference value L1. The change in the unevenness of the outer surface of the tire 3 that is not caused by the failure of the tire 3 is such that the distance L acquired by the failure detection unit 67 is the upper reference value L1 like the change in the unevenness of the outer surface due to the failure of the tire 3. Is rarely exceeded. This is because the unevenness of the outer surface due to the case not caused by the failure of the tire 3 does not mean that the outer surface of the tire 3 bulges, for example, rubber debris temporarily adheres to the outer surface. Because it occurs. Here, the predetermined clear time T1 is a time longer than at least the time required for the tire 3 rotating in the tire durability test to rotate once.

  Next, when the count clear unit 69 of the processing unit 62 determines that the measured count time interval T exceeds the predetermined clear time T1, the count clear unit 69 clears the count of the count unit 63 (step ST270). That is, if T> T1, N = 0. Thereby, when the counting part 63 counts by changes other than the change of the unevenness | corrugation of the outer surface by failure of the tire 3, this count is cleared.

  Next, the failure detection unit 67 of the processing unit 62 determines that the time interval T of the count measured by the count clear unit 69 is equal to or less than the predetermined clear time T1, or when the count of the count unit 63 is cleared, the counter unit 63 It is determined whether or not the number N counted in (1) exceeds the first failure number (step ST280).

  Next, when it is determined that the number of times N counted by the counter unit 63 by the failure detection unit 67 of the processing unit 62 does not exceed the first number of failures N1, the number of times N counted by the counter unit 63 is the first number of failures N1. Step ST220 to Step ST280 are repeated until the value exceeds.

  Next, the failure detection unit 67 of the processing unit 62 detects a failure of the tire 3 when determining that the number of times N counted by the counter unit 63 exceeds the first number of failures N1 (step ST290).

  As described above, when the count time interval T exceeds the predetermined clear time T1, that is, the detected distance L1, which is a physical quantity, does not exceed the range between the upper limit reference value L1 and the lower limit reference value L2, which are reference values. If so, clear the count. Therefore, the counter unit 64 is counted only when the outer surface irregularities due to the failure of the tire 3 are continuously changed. Thereby, malfunction can be further suppressed, suppressing the fall of the precision as a tire durability test.

  The tire durability test apparatus 1-3 according to Example 3 is a tire durability test for a pneumatic tire in which the physical quantity based on the unevenness of the outer surface or the amount of change in the physical quantity already exceeds the reference value when performing the tire durability test. It is possible to detect a failure of the pneumatic tire even if the operation is performed. The basic configuration of the tire durability test apparatus 1-3 according to Example 3 is the same as the basic configuration of the tire durability test apparatus 1-2 according to Example 2 as shown in FIG. Is omitted.

  Next, a tire failure detection method according to Example 3 will be described. FIG. 10 is a flowchart of the tire failure detection method according to the third embodiment. Here, in the tire failure detection method according to the third embodiment, a case will be described in which the tire failure detection is performed on the tire 3 whose physical quantity based on the unevenness of the outer surface already exceeds the reference value. The tire failure detection method according to the second embodiment shown in FIG. 10 has the same basic configuration as the tire failure detection method according to the first embodiment shown in FIG. 2 and FIG. .

  First, in the tire failure detection method according to the third embodiment, as shown in FIG. 10, the reference value setting unit 66 of the processing unit 62 of the control device 6-2 sets the upper limit reference value L1 and the lower limit reference value L2 as reference values. Setting is performed (step ST310). Here, as the upper limit reference value L1 and the lower limit reference value L2, for example, those calculated by the reference value setting method shown in FIG. 3 in the previous tire durability test performed on the tire 3 of the same size are used. This is because the tire 3 used in the tire durability test has an outer surface formed with unevenness that is greater than the change in the unevenness of the outer surface due to swelling when a failure occurs in the tire 3. Therefore, even if the upper limit reference value L1 and the lower limit reference value L2 are calculated based on the tire 3 used in the tire durability test using the reference value setting method shown in FIG. The range between the upper limit reference value L1 and the lower limit reference value L2 in which the distance L, which is a physical quantity based on the outer surface unevenness of the tire 3, is the reference value even if the unevenness of the outer surface changes due to the swelling. Is not exceeded. That is, it is impossible to detect a failure of the tire 3 used in the tire durability test.

In the tire failure detection method according to the third embodiment, the setting of the upper limit reference value L1 and the lower limit reference value L2, which are reference values, is not limited to the above. For example, in the reference value setting method shown in FIG. 3, it is determined whether or not the determined maximum value L _MAX exceeds the change in the unevenness of the outer surface due to bulging when a failure occurs in the tire 3. the following large distance L between the maximum value L _MAX as the maximum value L _MAX, may be calculated upper limit reference value L1 and the lower limit reference value L2.

  Next, when the tire durability test is started, the physical quantity acquisition unit 65 of the processing unit 62 acquires a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 (step ST320).

  Next, the failure detection unit 67 of the processing unit 62 determines whether the distance L detected and acquired by the physical quantity detection device 5 is not more than the upper limit reference value L1 and not less than the lower limit reference value L2 ( Step ST330). Here, the tire 3 used in the tire endurance test has an upper reference value L1 that is a distance L that is a physical quantity based on the unevenness of the outer surface of the tire 3 before the failure of the tire 3 occurs. The range between the lower limit reference value L2 is exceeded. Accordingly, when the physical quantity acquisition unit 65 continues to acquire the distance L, a waveform of the distance L corresponding to the number of rotations of the tire 3 is formed as indicated by G in FIG. As shown in the figure, in the tire 3, the distance L exceeds the upper limit reference value L1 once during one rotation before the failure occurs.

  Next, as illustrated in FIG. 10, the counter unit 63 of the control device 6-3 has the distance L acquired by the failure detection unit 67 of the processing unit 62 exceeding the upper limit reference value L1 or less than the lower limit reference value L2. Is determined (step ST340). Therefore, before this failure occurs, in the tire 3 whose physical quantity exceeds the reference value, the counter unit 63 continuously counts every rotation of the tire 3.

  Next, the count interval measuring unit 68 of the processing unit 62 measures the time interval T of counting (step ST350).

  Next, the count clear unit 69 of the processing unit 62 determines whether or not the measured count time interval T is less than the tire rotation time T2 (step ST360). As described above, as shown in FIG. 11, before the tire 3 breaks down, the distance L exceeds the upper limit reference value L1 once every time the tire 3 makes one revolution. Therefore, the number of times counted by the counting unit 63 may become the first failure number N1 before the failure of the tire 3 occurs. Here, when a failure occurs in the tire 3, the distance L exceeds the upper limit reference value L1 twice every time the tire 3 makes one rotation. That is, the count time interval T is equal to or longer than the time for one rotation of the tire 3 before the failure occurs, but is less than the time for one rotation of the tire 3 after the failure occurs. Accordingly, the count clear unit 69 determines whether or not the count time interval T has become shorter due to the failure of the tire 3. Here, the tire rotation time T2 is the time for one rotation of the rotating tire 3 in at least the tire durability test.

  Next, as shown in FIG. 10, when the count clear unit 69 of the processing unit 62 determines that the measured time interval T is equal to or greater than the tire rotation time T2, the count of the count unit 63 is cleared (step). ST370). That is, if T> T1, N = 0. As a result, the outer surface of the tire 3 is formed by unevenness other than the change of the unevenness of the outer surface due to the failure of the tire 3 or the change of the unevenness of the outer surface due to the failure of the tire 3. If is counted, this count is cleared.

  Next, the count clear unit 69 of the processing unit 62 determines that the measured time interval T is less than the tire rotation time T2, or when the count of the count unit 63 is cleared, the counter unit 63 counts it. It is determined whether or not the number N of times exceeds the second number of failures (step ST380). As described above, when a failure occurs in the tire 3, the distance L exceeds the upper limit reference value L1 twice every time the tire 3 rotates once. Therefore, when the tire 3 fails, the tire 3 rotates once. Each time, the number N counted by the counting unit 63 is doubled. Therefore, it is preferable that the second failure frequency N2 is twice the first failure rotation speed N1.

  Next, when it is determined that the number of times N counted by the counter unit 63 by the failure detection unit 67 of the processing unit 62 does not exceed the second number of failures N2, the number of times N counted by the counter unit 63 is the second number of failures N2. Step ST320 to Step ST380 are repeated until the value exceeds.

  Next, the failure detection unit 67 of the processing unit 62 detects a failure of the tire 3 when determining that the number of times N counted by the counter unit 63 exceeds the second number of failures N2 (step ST390).

  As described above, when the counting time interval T is less than the tire rotation time T2, which is the time for one rotation of the tire 3, that is, during the one rotation of the tire 3, the distance L1 that is the detected physical quantity is the reference value. When the range between the upper limit reference value L1 and the lower limit reference value L2 is more than twice, the failure of the tire 3 is detected when the number N exceeds the second failure number N2. Thereby, even if the distance L, which is a physical quantity based on the unevenness of the outer surface of the tire 3 before the failure, exceeds the range between the upper limit reference value L1 and the lower limit reference value L2, which is the reference value, the failure of the tire 3 can be prevented. Can be detected.

In the second and third embodiments, the reference value setting method according to the modified example may be used in the first embodiment. That is, a value obtained by subtracting the intermediate value L _MID from the distance L, which is a change amount of the physical quantity based on the unevenness of the outer surface of the rotating tire 3 in the detected tire durability test, is set before the tire durability test or the tire durability test. It may be determined whether or not a range between the upper limit reference value L3 and the lower limit reference value L4, which is a reference value based on the unevenness of the outer surface of the tire 3 immediately after the start, is exceeded.

  Moreover, in the said Examples 1-3, although the physical quantity detection apparatus 5 detects the physical quantity based on the unevenness | corrugation of the outer surface of the tire 3 via the contact body 51, this invention is not limited to this. . For example, the displacement meter 52 may directly measure the distance to the outer surface of the tire 3, and the physical quantity detection device 5 may detect a physical quantity based on the unevenness of the outer surface of the tire 3. That is, the physical quantity detection device 5 may detect a physical quantity based on the unevenness of the outer surface of the tire 3 without directly contacting the tire 3.

  Moreover, in the said Examples 1-3, although the physical quantity detection apparatus 5 detects the distance L which is a physical quantity based on the unevenness | corrugation of the outer surface of the tire 3 via the contact body 51 by the displacement form 52, this invention is It is not limited to this. For example, the speed may be detected as a physical quantity based on the unevenness of the outer surface of the tire 3 using a speedometer. Moreover, you may detect an acceleration as a physical quantity based on the unevenness | corrugation of the outer surface of the tire 3 using an acceleration timepiece. Moreover, you may detect a weight as a physical quantity based on the unevenness | corrugation of the outer surface of the tire 3 using a load cell.

  As described above, the tire failure detection method, the tire failure detection program, and the tire failure detection device according to the present invention are useful when testing the durability performance of a tire, and particularly suppress the decrease in accuracy as a tire durability test. However, it is suitable for suppressing malfunction.

It is a figure which shows the structural example of a tire durability test apparatus provided with the tire failure detection apparatus which performs the tire failure detection method concerning Example 1. FIG. It is a figure which shows the flowchart of the tire failure detection method concerning Example 1. FIG. It is a figure which shows the flowchart of the reference value setting method concerning Example 1. FIG. It is explanatory drawing of the reference value setting method. It is a figure which shows the change of the unevenness | corrugation of the outer surface of a tire. It is a figure which shows the flowchart of the tire failure detection method concerning the modification of Example 1. FIG. It is a figure which shows the flowchart of the reference value setting method concerning the modification of Example 1. FIG. It is a figure which shows the structural example of a tire durability test apparatus provided with the tire failure detection apparatus which performs the tire failure detection method concerning Example 2. FIG. It is a figure which shows the flowchart of the tire failure detection method concerning Example 2. FIG. It is a figure which shows the flowchart of the tire failure detection method concerning Example 3. FIG. It is a figure which shows the change of the unevenness | corrugation of the outer surface of a tire.

Explanation of symbols

1-1-3 Tire durability test device 2 Test drum 3 Tire 4 Support device 5 Physical quantity detection device (physical quantity detection means)
6-1-3 Control device (tire failure detection device)
61 I / O port 62 Processing unit 63 Counter unit 64 Storage unit 65 Physical quantity acquisition unit 66 Reference value setting unit (reference value setting means)
67 Failure detection unit (failure detection means)
68 Count interval measuring unit (count interval measuring means)
69 Count clear part (count clear means)
7 Rim 8 Input / output device 81 Input means 82 Display means

Claims (13)

In a tire failure detection method for detecting a failure of a rotating pneumatic tire during a tire durability test,
A reference value setting procedure for setting a reference value based on the irregularities of the outer surface of the pneumatic tire before the tire durability test or immediately after the start of the tire durability test;
A physical quantity detection procedure for detecting a physical quantity based on irregularities on the outer surface of the rotating pneumatic tire;
A counter procedure that counts when the detected physical quantity or the change amount of the detected physical quantity exceeds the reference value;
A failure detection procedure for detecting a tire failure when the counted number exceeds a first failure number;
A tire failure detection method comprising: A count interval measurement procedure for measuring the time interval of the count;
When the measured count time interval exceeds a predetermined clear time, a count clear procedure for clearing the count,
The tire failure detection method according to claim 1, further comprising:   The tire failure detection step detects a tire failure when the number of times that the time interval of the measured count is less than a time during which the pneumatic tire makes one rotation exceeds a second failure number. Or the tire failure detection method according to 2;   The tire failure detection method according to any one of claims 1 to 3, wherein in the physical quantity detection procedure, the physical quantity is detected by a contact body that contacts the outer surface and behaves according to the unevenness. .   The tire failure detection method according to any one of claims 1 to 4, wherein the physical quantity is at least one of distance, speed, acceleration, and load.   The tire failure detection method according to any one of claims 1 to 5, wherein the outer surface is an outer surface in a sidewall portion of the pneumatic tire.   A tire failure detection program for causing a computer to execute the tire failure detection method according to any one of claims 1 to 6. In a tire failure detection device that detects a failure of a rotating pneumatic tire during a tire durability test,
Reference value setting means for setting a reference value based on the unevenness of the outer surface of the pneumatic tire before the tire durability test or immediately after the start of the tire durability test,
A physical quantity detection means for detecting a physical quantity based on irregularities on the outer surface of the rotating pneumatic tire;
Counter means for counting when the detected physical quantity or a change amount of the detected physical quantity exceeds the reference value;
A failure detection means for detecting a tire failure when the counted number exceeds the first failure number;
A tire failure detection device comprising: A count interval measuring means for measuring the time interval of the count;
When the time interval of the measured count exceeds a predetermined clear time, count clear means for clearing the count,
The tire failure detection device according to claim 8, further comprising:   9. The failure detection means detects a tire failure when the number of times that the time interval of the measured count is less than the time for which the pneumatic tire makes one revolution exceeds a second number of failures. Or the tire failure detection device according to 9.   The tire failure detection device according to any one of claims 8 to 10, wherein the physical quantity detection means includes at least one of a distance meter, a speedometer, an acceleration watch, and a load cell.   The tire failure detection device according to any one of claims 8 to 11, wherein the physical quantity detection means detects the physical quantity by a contact body that contacts the outer surface and behaves according to the unevenness. .   The tire failure detection device according to any one of claims 8 to 12, wherein the outer surface is an outer surface of a sidewall portion of the pneumatic tire.

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