JP2004177240A - Tire failure detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire failure detection method for detecting an internal failure of a tire with accuracy higher than before. <P>SOLUTION: According to this tire failure detection method, an internal failure is detected occurring in a pneumatic tire 2 rotating on a test drum 1. A process is repeated of measuring the surface position of the rotating tire 2 by a non-contact type displacement meter 3 along the tire circumferential direction over the entire circumference thereof. Front and rear surface position data measured before and after a prescribed time interval are compared with each other with respect to severally corresponding positions on the circumference of the tire to calculate the amount of change. When the amount of change is equal to or more than a prescribed threshold, an internal failure is determined to have occurred. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tire failure detection method, and more particularly, to a tire failure detection method capable of detecting an internal failure of a tire with higher accuracy than before.
[0002]
[Prior art]
Generally, in a tire endurance test, a contact-type failure detection device is used to detect an internal failure of the tire, and its detection unit is arranged near the surface of a pneumatic tire rotating on a test drum, and inflated due to the internal failure. The detected tire surface comes into contact with the detection unit to detect a tire failure (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-57-93230
[Problems to be solved by the invention]
However, in the method of detecting with the contact-type failure detection device described above, when the pneumatic tire is continuously rotated on the test drum for a long time, the tire internal pressure increases due to the temperature rise of the tire, and the pneumatic tire moves radially outward. When the rotational speed is increased, or when the rotational speed is increased, the pneumatic tire expands radially outward due to centrifugal force. Since the portion on the opposite side swells, it is necessary to separate the detection unit to some extent to eliminate the effect, and as a result, it is not possible to detect the inside where the amount of swelling is small and it is not possible to measure with high accuracy .
[0005]
Therefore, when the tire surface bulged due to an internal failure is a small displacement with a small local bulge amount, the bulged tire surface may cause tire breakage before coming into contact with the detection unit. If the tire is broken before the internal failure is detected as described above, it is not possible to identify the location of the failure and to analyze the growth process of the failure, which hinders progress in improving the tire.
[0006]
An object of the present invention is to provide a tire failure detection method capable of detecting an internal failure of a tire with higher accuracy than before.
[0007]
[Means for Solving the Problems]
The tire failure detection method of the present invention that achieves the above object is a tire failure detection method for detecting that an internal failure has occurred in a pneumatic tire that rotates on a test drum, wherein the surface position of the rotating pneumatic tire is Is repeated over the entire circumference along the tire circumferential direction using a non-contact displacement meter, and the front and rear surface position data measured at predetermined time intervals are compared at each corresponding position on the tire circumference. Then, the amount of change is calculated, and when the amount of change at any position is equal to or greater than a predetermined threshold, it is determined that an internal failure has occurred.
[0008]
As described above, the non-contact displacement meter is used to determine the occurrence of an internal failure by using the temporal displacement of the front and rear tire surface position data measured at intervals. Even small displacements with small local bulges can be detected, so it is possible to detect the tire surface bulged due to internal failure with higher accuracy than before using a contact failure detection device. it can.
[0009]
Another tire failure detection method of the present invention is a tire failure detection method for detecting that an internal failure has occurred in a pneumatic tire rotating on a test drum, wherein the surface position of the rotating pneumatic tire is determined. Repeat the process of measuring with a non-contact type displacement meter over the entire circumference along the tire circumferential direction, and compare the front and rear surface position data measured at predetermined time intervals at each corresponding position on the tire circumference. Then, the amount of change is calculated, and when a difference between the amounts of change at any position is equal to or larger than a predetermined threshold value, it is determined that an internal failure has occurred.
[0010]
By determining that an internal failure has occurred when the difference in the amount of change at any position on the circumference is equal to or greater than a predetermined threshold value, an increase in the internal pressure due to a rise in the temperature of the tire or an increase in the rotational speed of the tire When the pneumatic tire expands radially outward due to an increase in centrifugal force, or in the case of a radial tire, even if the part on the opposite side to the part of the pneumatic tire in contact with the test drum expands due to the increase in applied load Thus, the tire surface swelled due to an internal failure can be reliably detected without being affected by the internal failure.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0012]
FIG. 1 shows an example of implementing the tire failure detection method of the present invention in a tire durability test, wherein 1 is a test drum, 2 is a pneumatic tire, and 3 is a pneumatic wheel rotating on the test drum 1 by a rotating test drum 1. A non-contact type displacement meter that measures the surface position of the tire 3 is a processing unit that processes data input from the non-contact type displacement meter 3, and 5 is a light source.
[0013]
The test drum 1 is rotatably installed so that the rotation speed can be changed to an arbitrary speed.
[0014]
The pneumatic tire 2 assembled to the wheel 6 and filled with a predetermined air pressure is rotatably supported by a tire support shaft (not shown), and abuts on the outer peripheral surface of the rotating test drum 1 so that the pneumatic tire 2 is moved on the test drum 1. It runs in rotation. A predetermined load can be applied to the pneumatic tire 2 via a tire support shaft.
[0015]
The non-contact displacement meter 3 is configured by a perspective displacement meter including a camera, and captures an image of the surface of the pneumatic tire 2 irradiated to the light source 5. In the tire durability test, it is preferable that the non-contact displacement meter 3 be installed so as to face the belt end of the shoulder portion where the failure is most likely to occur.
[0016]
The processing unit 4 calculates surface position data from the captured image data. Further, the front and rear surface position data measured at predetermined time intervals are compared over one round at each corresponding position on the tire circumference, and the change amount, that is, the swelling amount of the tire surface is calculated, If at least one of the values exceeds a predetermined threshold, it is determined that an internal failure has occurred, the rotation of the test drum 1 is stopped via a control unit (not shown), and the tire durability test is terminated. It is.
[0017]
A well-known rotary encoder attached to a tire support shaft is used as a means for identifying each corresponding position on the tire circumference. However, a reflective sheet attached to a sidewall portion or a rim portion of a rotating tire is used. Each corresponding position on the tire circumference may be obtained by irradiating light and using the position where the reflected light is detected as a reference position.
[0018]
Hereinafter, the tire failure detection method of the present invention in a tire durability test will be described with reference to the flow of FIG.
[0019]
First, the light source 5 is turned on, the test drum 1 is rotated, and the pneumatic tire 2 is rotated on the test drum 1. When a predetermined endurance test start speed is reached, images of the surface of the pneumatic tire 3 illuminated by the camera 3 onto the light source 5 are continuously captured, and the surface position of the pneumatic tire 2 is set along the tire circumferential direction over the entire circumference. The step of measuring is repeated (step a).
[0020]
When a predetermined time elapses (step b), the processing unit 4 compares the front and rear surface position data measured at predetermined time intervals at each corresponding position on the tire circumference over one round, and determines each correspondence. The amount of change at each of the positions to be changed is calculated (step c).
[0021]
Subsequently, each obtained change amount is compared with a predetermined threshold value set in advance, and if any one of the change amounts is equal to or more than the predetermined threshold value (step d), it is determined that an internal failure has occurred. Then, the rotation of the test drum 1 is stopped via a control unit (not shown) (step e), and the tire durability test ends. In step d, if each of the change amounts is smaller than the predetermined threshold, the process returns to step a and repeats the subsequent steps in order to continue measuring the surface position of the pneumatic tire 2.
[0022]
As described above, in the present invention, the occurrence of an internal failure is determined by using the non-contact displacement meter 3 and using the temporal displacement of the tire surface position data before and after measured at intervals. Even if the tire surface bulged due to the failure is local and the amount of bulge is small and small, it can be detected. Therefore, it is possible to detect the tire surface bulging due to an internal failure with higher accuracy than before.
[0023]
In addition, by capturing images with a non-contact displacement meter 3 using a perspective displacement meter such as a camera, the tire surface bulged due to an internal failure without being affected by grooves or kerfs provided on the tire surface. Can be detected.
[0024]
FIG. 3 shows another example of the tire failure detection method according to the present invention, in which the processing unit 4 further compares the calculated change amounts, and compares the change amounts (the difference between the maximum change amount and the minimum change amount, or When at least one difference between adjacent change amounts is equal to or greater than a predetermined threshold value, it is determined that an internal failure has occurred. The difference between step c and step d in FIG. A step c ′ for calculating a difference in the amount of change is added.
[0025]
By determining that an internal failure has occurred when the difference between the change amounts is equal to or greater than a predetermined threshold value, an increase in the internal pressure due to a rise in the temperature of the tire, or an increase in the centrifugal force due to an increase in the tire rotation speed, Even if the tread portion 2A of the pneumatic tire 2 expands radially outward, the tire surface that has expanded due to an internal failure can be reliably detected without being affected by the expansion.
[0026]
The see-through type displacement meter including the above-described camera is used to measure the tire surface position between the tire maximum width positions P of the left and right sidewall portions 2B of the toroidal pneumatic tire 2. When measuring the tire surface position on the bead portion 2C side from the tire maximum width position P which cannot be measured by the see-through displacement meter, another tire failure detection method of the present invention shown in FIG. 4 can be used.
[0027]
In FIG. 4, the non-contact type displacement meter 3 is constituted by a reflection type displacement meter including a laser displacement meter instead of the above-described camera. The surface position of the rotating pneumatic tire 2 is measured by a laser displacement meter in the same manner as described above, and the processing unit 4 compares the front and rear surface position data measured at predetermined time intervals in the same manner as described above. A comparison is made over one lap at each corresponding position on the lap, and it is determined that an internal failure has occurred if the amount of change at any position on the lap is equal to or greater than a predetermined threshold, or a change on the lap. When the difference between the amounts becomes equal to or larger than the predetermined threshold value, it is determined that an internal failure has occurred, the rotation of the test drum 1 is stopped, and the tire durability test is terminated.
[0028]
Thus, by measuring the tire surface position on the bead portion 2C side from the tire maximum width position P, which cannot be measured by the see-through type displacement meter, using the reflection type displacement meter, the non-contact type displacement meter 3 expands due to an internal failure. The released tire surface can be detected by the entire tire.
[0029]
The above-described tire failure detection method of the present invention can be preferably used in a tire durability test, but is not limited thereto, and can be applied to, for example, a device that is mounted on a vehicle and detects a tire failure. At this time, when the processing unit 4 determines that an internal failure of the tire has occurred, it is preferable to include a mechanism for generating an alarm to notify the driver of the failure.
[0030]
【The invention's effect】
As described above, the present invention uses a non-contact type displacement meter, and the amount of change in any position on the circumference of the front and rear surface position data measured at predetermined time intervals, or the change on the circumference. Since it is determined that an internal failure has occurred when the difference in the amount is equal to or greater than a predetermined threshold, even if the tire surface bulged due to the internal failure is a small displacement with a small local bulge amount, The tire failure can be detected with higher accuracy than before.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of implementing a tire failure detection method of the present invention in a tire durability test.
FIG. 2 is a flowchart illustrating a tire failure detection method according to the present invention.
FIG. 3 is a flowchart showing another example of the tire failure detection method of the present invention.
FIG. 4 is an explanatory view showing still another example of implementing the tire failure detection method of the present invention in a tire durability test.
[Explanation of symbols]
Reference Signs List 1 Test drum 2 Pneumatic tire 3 Non-contact type displacement meter 4 Processing unit 5 Light source 6 Wheel P Tire maximum width position

Claims (4)

A tire failure detection method for detecting that an internal failure has occurred in a pneumatic tire rotating on a test drum, wherein the non-contact type displacement of the surface position of the rotating pneumatic tire over the entire circumference along the tire circumferential direction. It repeats the process of measuring with a meter, calculates the amount of change by comparing the front and rear surface position data measured at predetermined time intervals at each corresponding position on the tire circumference, and at any position A tire failure detection method for determining that an internal failure has occurred when the amount of change is equal to or greater than a predetermined threshold. A tire failure detection method for detecting that an internal failure has occurred in a pneumatic tire rotating on a test drum, wherein the non-contact type displacement of the surface position of the rotating pneumatic tire over the entire circumference along the tire circumferential direction. It repeats the process of measuring with a meter, calculates the amount of change by comparing the front and rear surface position data measured at predetermined time intervals at each corresponding position on the tire circumference, and at any position A tire failure detection method for determining that an internal failure has occurred when the difference between the amounts of change is equal to or greater than a predetermined threshold. 3. The non-contact type displacement meter according to claim 1, wherein the displacement meter measures a tire surface position between tire maximum width positions of left and right sidewalls of the pneumatic tire. 3. Tire failure detection method. 3. The non-contact type displacement meter is a reflection type displacement meter, and the displacement meter measures a tire surface position on a bead portion side from a tire maximum width position on left and right sidewall portions of the pneumatic tire. The tire failure detection method described in the above.

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