JP2009019950A - Method and device for estimating tire abrasion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device therefor having excellent durability, capable of accurately estimating the abrasion degree of a tire. <P>SOLUTION: An acceleration sensor 11 is provided on the inner surface side of an inner liner part of the tire, and an acceleration waveform in the tire diameter direction of a tire tread is detected, and a deformation time being a time between two peaks corresponding to a swelling point appearing in the acceleration waveform is calculated. A deformation length X which is an index of a grounding out-of-plane deformation range of the tire is calculated, and a grounding time which is a time between two peaks corresponding to the ground contact end of the tread appearing in a differential waveform which is a time-series waveform of a differentiated value of the acceleration is calculated, and a grounding length L which is an index of a deflection amount of the tire is calculated. The abrasion degree of the tire is estimated based on the calculated deformation length X and grounding length L and a map 17M showing a relation between the deformation length X corresponding to the abrasion degree of the tire and the grounding length L, determined beforehand. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for estimating the degree of tire wear.

Generally, when a tire is worn, drainage performance is lowered, and a braking distance on a wet road surface is increased. In addition, with a studless tire, the grip performance on an icy and snowy road surface decreases due to wear. Furthermore, excessive wear is very dangerous because water can enter the tread belt and cause tire destruction. In the case of a small passenger car, rubber protrusions called slip signs appear in the groove when the remaining groove amount of the tire is 1.6 mm. Considering the driving safety of the vehicle, tires should be replaced before the appearance of the slip sign, but there are not many drivers who are indifferent to such maintenance.
In order to warn the driver, a technique for automatically detecting tire wear is required. In terms of vehicle control, it is expected to grasp changes in tire characteristics due to wear and realize safer control.
As a method for estimating tire wear, conventionally, the tire dynamic radius is calculated by calculating the absolute speed of the vehicle using a GPS or an optical sensor and comparing it with the wheel rotational speed. A method for obtaining the tire wear amount from the difference in tire radii is known. However, even if the tire is completely worn, the difference between the rotational speed of the tire and the rotational speed of a new tire is at most about 1%. In actual driving, it includes stable inner and outer wheel errors during turning, errors due to acceleration slip during braking and driving, and errors due to gradients. It was difficult to do.
Therefore, the tread portion is embedded with a detection body made of a magnetic material, and a magnetic sensor is disposed on the vehicle body side to detect that the detection body is worn by tire wear and the detection signal changes, thereby detecting the tread portion. A method for estimating wear on the tread part by embedding a sensor with a resistor made of conductive rubber and detecting that the characteristic value of the sensor changes due to tire wear is proposed. (For example, see Patent Documents 1 and 2).
JP 2003-214808 A JP 2005-28950 A

  However, in the method of embedding a magnetic material or conductive rubber in the tread part, when wear progresses, the detection body and sensor are exposed to the grounding surface, so there is a concern about the adverse effect on the durability of the tire. When rubber having different physical properties is exposed on the tread surface, there is a problem that the grip strength of the tire is reduced, and that these become crack fracture nuclei.

  The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a method and an apparatus capable of accurately estimating the wear degree of a tire while being excellent in durability.

FIG. 6A is a schematic diagram showing an outer shape of the tire when the tire is bent by applying a load, and FIG. 6B is an enlarged view of the vicinity of the road surface. When a load is applied to the tire, the ground contact surface is pushed toward the center of the tire, and the periphery thereof is deformed so as to swell outward from the initial profile indicated by the one-dot chain line in FIG. Here, the point that swells outward most outside the ground plane is defined as a bulging point.
As a result of diligent study, the inventor compared the outer shape of a worn tire indicated by a broken line in the same figure with the outer shape of a new tire indicated by a solid line in the same figure. Since the bulging point is closer to the ground contact surface, by comparing the amount of deflection of the tire and the range of deformation outside the ground contact surface that is the length along the tire between the bulging points, the load and The present inventors have found that the wear of a tire can be accurately estimated even when the wear form of the tire is different, and have arrived at the present invention.
That is, the invention according to claim 1 of the present application is a method for estimating tire wear, and based on input information from a sensor disposed in a tire tread portion, a range of out-of-ground deformation of the tire tread portion. And an index indicating the amount of deflection of the tire at that time, and the degree of wear of the tire is estimated from the relationship between the calculated index of the outside-surface deformation range and the index of tire deflection. It is characterized by this. As a result, for example, even if the tire wear form is different from the center part, for example, the shoulder part is more worn out, or even if the load changes due to the weight being loaded, the tire wear accuracy is improved. Can be estimated well.

The invention according to claim 2 is the tire wear estimation method according to claim 1, wherein the sensor is an acceleration sensor, and a time series waveform of acceleration detected by the acceleration sensor or the acceleration is differentiated. From the time series waveform of the value or the time series waveform of the value obtained by integrating the acceleration, the index of the out-of-contact surface deformation range and the index of the tire deflection amount are calculated. The above indices can be calculated with high accuracy.
The time series waveform of acceleration is the time series waveform of acceleration sensor outputs that change with time. The acceleration waveform and the time series waveform of acceleration are the same, and the acceleration waveform is differentiated. Both the waveform and the integrated waveform are time-series waveforms.
A third aspect of the present invention is the tire wear detection method according to the second aspect, wherein the acceleration detection direction is a tire radial direction or a tire circumferential direction, whereby the index is more accurately determined. It can be calculated.
The invention according to claim 4 is the tire wear estimation method according to claim 1, wherein the sensor is a strain sensor, and the time series waveform of the tire circumferential strain detected by the strain sensor, or the tire The index of the out-of-surface deformation range and the index of tire deflection are calculated from either a time-series waveform of a value obtained by differentiating strain or a time-series waveform of a value obtained by differentiating the strain. Is. As described above, tire wear can be accurately estimated even when the circumferential distortion waveform of the tire tread portion is used instead of the acceleration.
According to a fifth aspect of the present invention, in the tire wear estimation method according to any one of the second to fourth aspects, the sensor is disposed in an inner liner portion of the tire, whereby the sensor is placed in the tread rubber. The durability of the sensor can be improved as compared with the case where the sensor is disposed in the sensor.

A sixth aspect of the present invention is the tire wear estimation method according to any one of the second to fourth aspects, wherein the time between two peaks corresponding to the deformation of the tread that appears in the time series waveform outside the contact surface. The deformation length obtained by multiplying the calculated deformation time by the tire speed is used as an index of the tire contact surface out-of-plane deformation range. It is possible to accurately calculate the index of the deformation range outside the ground plane.
Further, the invention according to claim 7 is the tire wear estimation method according to any one of claims 2 to 5, wherein the tread between the two peaks corresponding to the deformation outside the contact surface of the tread appearing in the time series waveform. And a deformation time ratio obtained by dividing the calculated deformation time by the time required for one rotation of the tire is used as an index of the tire contact surface out-of-plane deformation range. Therefore, this method can also accurately calculate the index of the deformation range outside the tire contact surface.
The invention according to claim 8 is the tire wear estimation method according to any one of claims 2 to 5, wherein the time between two peaks corresponding to the deformation at the contact end of the tread appearing in the time series waveform. The contact length obtained by multiplying the calculated contact time by the tire speed is used as an index of the tire deflection amount. The index can be calculated with high accuracy.
According to a ninth aspect of the present invention, in the tire wear estimation method according to any one of the second to fifth aspects, the time between two peaks corresponding to the deformation at the contact end of the tread that appears in the time series waveform. A certain contact time is calculated, and the contact time ratio obtained by dividing the calculated contact time by the time required for one rotation of the tire is used as an index of the tire deflection amount. An index of the amount of tire deflection can be calculated with high accuracy.
A tenth aspect of the present invention is the tire wear estimation method according to any one of the first to ninth aspects, wherein an upper limit value of the tire speed at which the degree of wear is estimated is set to 100 km / hr. Thus, stable wear estimation can be performed.
The invention according to claim 11 is the tire wear estimation method according to any one of claims 1 to 10, wherein the index representing the out-of-contact surface deformation range according to the degree of tire wear and the tire at that time The relationship between the index representing the amount of deflection is determined in advance, the relationship between the index representing the out-of-surface deformation range and the amount of tire deflection determined in advance, the index of the calculated out-of-surface deformation range and the tire The degree of wear of the tire is estimated by comparing the relationship with the index of the amount of deflection, and thereby the degree of wear of the tire can be estimated with higher accuracy.

The invention according to claim 12 is an apparatus for estimating tire wear, an acceleration sensor for detecting acceleration in a tire circumferential direction or a tire radial direction of a tread portion, and a tire having a time-series waveform of the detected acceleration. Out-of-surface deformation range calculation means for calculating an index of the out-of-contact surface deformation range of the tire from the peak corresponding to the bulging point, and differential for calculating a differential waveform of acceleration, which is a time-series waveform of values obtained by differentiating the acceleration. Waveform calculating means; deflection amount calculating means for calculating an index of the deflection amount of the tire from a peak corresponding to the tire ground contact edge of the differential waveform of the acceleration; and an index of the calculated out-of-contact surface deformation range and the deflection amount A wear state estimating means for estimating the wear of the tire from the index is provided. Thereby, the apparatus for implement | achieving said tire wear estimation method can be obtained.
The invention according to claim 13 is an apparatus for estimating tire wear, comprising a strain sensor for detecting a circumferential strain of a tread portion, and a tire bulging point of the time series waveform of the detected circumferential strain. Out-of-ground surface deformation range calculation means for calculating an index of the tire's out-of-ground surface deformation range from the corresponding peak, and differential for calculating a differential waveform of the circumferential strain, which is a time-series waveform of the value obtained by differentiating the above-mentioned circumferential strain. Waveform calculating means; deflection amount calculating means for calculating an index of the amount of deflection of the tire from a peak corresponding to the tire ground contact edge of the differential waveform of the circumferential distortion; and an index of the calculated out-of-surface deformation range and deflection A wear state estimating means for estimating the wear of the tire from the quantity index is provided. Also by this, the apparatus for implement | achieving said tire wear estimation method can be obtained.

Hereinafter, the best mode of the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram showing the configuration of a tire wear estimation apparatus 10 according to the best mode. In FIG. 1, 11 is an acceleration sensor for detecting the acceleration of the tire tread portion, and 12 is for detecting the rotational speed of the wheel. A wheel speed sensor 13 is an acceleration waveform extracting means for extracting a time series waveform of acceleration of the tire tread portion from the output of the acceleration sensor, and 14 is a differential waveform of acceleration which is a time series waveform obtained by differentiating the acceleration. The differential waveform calculation means 15 calculates a deformation time which is a time between two peaks corresponding to the bulging point appearing in the time series waveform of the acceleration, and multiplies the calculated deformation time by the tire speed, A deformation length calculation means 16 for calculating a deformation length X that is an index of the deformation range outside the ground contact surface of the tire, 16 is a change at the contact end of the tread that appears in the differential waveform of the acceleration. A contact length calculation means for calculating a contact length L that is an index of the amount of deflection of the tire; Reference numeral 17 denotes storage means for storing a map 17M indicating the relationship between the deformation length X and the contact length L corresponding to the tire wear degree obtained in advance, and 18 denotes the calculated deformation length X, the contact length L and the map. 17M is wear estimation means for estimating the degree of wear of the tire. In this example, the tire speed is calculated using the rotational speed of the wheel detected by the wheel speed sensor 12 and the diameter of the tire.
Further, in this example, as shown in FIG. 2, the acceleration sensor 11 is disposed at the center in the width direction of the tire of the inner liner portion 2 of the tire 1 so that the detection direction is the tire radial direction. The tire radial acceleration acting on the inner surface of the tire tread 3 is detected.
The wheel speed sensor 12 uses a well-known electromagnetic induction type wheel speed sensor that detects rotation of an axle by attaching a sensor unit including a yoke and a coil to a knuckle (not shown).
Further, each means from the acceleration waveform extracting means 13 to the wear estimating means 18 is installed on the vehicle body side and constitutes a calculation unit 19.
As a configuration for sending the output signal of the acceleration sensor 11 to the calculation unit 19, for example, as shown in FIG. 2, a transmitter 11F is installed in the inner liner part 2 or the wheel 4, and the output signal is sent by an amplifier (not shown). After amplification, it is preferable to transmit the signal to the calculation unit 19 wirelessly. In addition, it is good also as a structure which provides the calculating part 19 in the tire side and transmits the determination result of the wear estimation means 18 to the vehicle control apparatus which is not shown in figure on the vehicle body side.

Next, a tire wear estimation method according to the best mode will be described.
First, the acceleration sensor 11 detects the acceleration in the tire radial direction on the inner surface of the inner liner portion 2 that is deformed as the tire tread 3 is deformed. The acceleration waveform extracting means 13 extracts a time series waveform of the radial acceleration (hereinafter referred to as an acceleration waveform) from the output signal of the acceleration sensor. FIG. 3 is a diagram showing an example of the acceleration waveform, where the horizontal axis is time [sec.] And the vertical axis is the radial acceleration magnitude [G]. When the acceleration is a positive value, the acceleration is generated outside the tire, and when the acceleration is a negative value, the acceleration is generated in the tire center direction. This acceleration is generated approximately in proportion to the force that the tire tread receives in the radial direction, and is proportional to the amount of deformation in the radial direction with a slight phase difference.
The vicinity of the two peaks on the plus side is outside the ground contact surface, and since the tread is subjected to a force that deforms to the outside of the tire, it can be seen that the two peaks are bulging points. Accordingly, the time between the two peaks is defined as the deformation time, and the deformation length X is obtained by multiplying the deformation time by the speed. The deformation length calculation means 15 calculates the deformation length X from the acceleration waveform, and uses this as an index of the out-of-ground surface deformation range. In peak detection, depending on the sensitivity of the acceleration sensor 11, data is more stable when peak detection is performed after applying an appropriate low-pass filter. That is, more stable wear estimation can be performed. Also, since the time interval between the peaks varies greatly depending on the tire speed, changing the frequency of the low-pass filter according to the tire speed can make the waveform shape at each speed the same, so that more stable estimation is possible. It can be carried out.

The differential waveform calculation means 14 calculates a differential waveform of acceleration, which is a time series waveform of a value obtained by differentiating the acceleration extracted by the acceleration waveform extraction means 13. FIG. 4 is a diagram illustrating an example of the differential waveform of the acceleration. The horizontal axis represents time [sec.], And the vertical axis represents the radial acceleration differential value [G / sec.]. The peak in the figure corresponds to the point where the radial force received by the tread changes most. The time between the two peaks is defined as the contact time, and the contact length multiplied by the speed is defined as the contact length L. The contact length calculation means 16 calculates the contact length L from the differential waveform, and uses this as an index of the amount of deflection of the tire.
As shown in FIGS. 6 (a) and 6 (b), when a load is applied to the tire, the ground contact surface is pushed toward the center of the tire, and the periphery thereof is deformed to bulge outward from the initial profile indicated by the one-dot chain line in FIG. However, when the deflection amount of the tire is the same, that is, when the contact length L is the same, the deformation length X is shorter in the worn tire.
Therefore, the wear estimation means 18 determines the deformation length X calculated by the deformation length calculation means 15, the contact length L calculated by the contact length calculation means 16, and the degree of tire wear previously stored in the storage means 17. The degree of wear of the tire is estimated using a map 17M showing the relationship between the corresponding deformation length X and contact length L.

The relationship between the deformation length X and the contact length L was determined based on the following test results.
In order to examine not only the amount of wear but also the influence of the form of wear, the following four types of test tires were prepared. Needless to say, there are variations in the form of wear in the market, and it is important that the estimation error is small even if the wear form is different.
Test tire 1 to new tire; groove about 8mm
Test tire 2-worn tire; remaining groove about 4 mm,
Shoulder is worn out Test tire 3-Wear tire; Remaining groove about 4mm,
Form where the center part is worn out and the shoulder part remains Test tire 4-worn tire; remaining groove about 2 mm,
Level almost similar to wear and slip sign Test tires 1 to 4 are run at a speed of 40 km / h on a flat belt testing machine, and the acceleration in the tire radial direction is measured. The length L was calculated. The tire used was a tire of size 205 / 65R15, and the internal pressure at that time was 230 kPa. Further, the load was changed every 3 kN from 3 to 7 kN.
The relationship between the contact length L and the deformation length X is shown in the graph of FIG. The horizontal axis of the graph is the contact length L (m), and the vertical axis is the deformation length X (m). From this graph, the test tire 1, the test tires 2, 3 and the test tire 4 are on separate lines, and when compared with the same contact length L, the deformation length X becomes shorter as the wear progresses. I understand that.
Further, the test tire 2 indicated by □ and the test tire 3 indicated by △ in FIG. In general, the contact length L and the deformation length X differ depending on the form of wear, but they move on the same line in the graph. Therefore, if the wear of the tire is estimated from the relationship between the contact length L and the deformation length X, the wear level can be estimated stably even if the form of wear is different.
By the way, when the tire speed increases, the influence of the centrifugal force on the deformation increases, and as a result, the relationship between the contact length L and the deformation length X also changes. Therefore, more stable wear estimation can be realized by setting an upper limit value of the tire speed at the time of estimation and estimating on the low speed side. Further, since the progress of wear is very slow, there is no problem in practical use even if it cannot be estimated during high-speed driving. Although it depends on the type of tire, if the tire speed exceeds 100 km / hr, the influence of centrifugal force on the tire dynamic radius increases, so measurement at 100 km / hr or less is preferable. In addition, when the said test was done by changing tire speed, it was confirmed that each line is stable without moving in the range up to 100 km / hr.

  Thus, in this best mode, the acceleration sensor 11 is provided on the inner surface of the inner liner portion 2 of the tire 1 to detect a time series waveform (acceleration waveform) of the tire tread 3 in the tire radial direction, and this acceleration waveform. When calculating the deformation time, which is the time between two peaks corresponding to the bulging point appearing on the tire, calculating the deformation length X, which is an index of the deformation range outside the contact surface of the tire, and the value obtained by differentiating the acceleration The contact time L, which is the time between two peaks corresponding to the contact edge of the tire tread 3 appearing in the differential waveform which is a series waveform, is calculated, and the contact length L which is an index of the deflection amount of the tire is calculated. The degree of wear of the tire is estimated based on the deformation length X, the contact length L, and a map 17M showing the relationship between the deformation length X and the contact length L corresponding to the previously determined degree of tire wear. Because it was Unishi, even if the wear type of load and the tire is different, it is possible to accurately estimate the wear of the tire. In addition, since the acceleration sensor 11 is not exposed to the tire tread, it is excellent in durability, and tire wear can be estimated without impairing tire performance such as gripping force.

In the best mode, the acceleration sensor 11 is arranged at the center in the width direction of the tire on the inner surface of the inner liner portion 2 of the tire 1 as shown in FIG. Further, the same effect can be obtained even if the belt layer is disposed inside the belt layer or outside the belt layer in the tire radial direction and inside the groove portion formed in the tread rubber. However, in consideration of durability and ease of attachment, it is more advantageous to attach to the inner surface side of the inner liner portion 2 as in this example.
In the above example, the tire speed is detected using the wheel speed sensor 12, but a speed sensor or an acceleration sensor is provided on the vehicle body side to measure the vehicle speed, and the tire speed is obtained from the vehicle speed. You may do it.
Since the peak of the acceleration waveform or the peak of the differential waveform appears repeatedly every rotation of the tire, the tire speed may be calculated using the time interval of the peak and the diameter of the tire.

In the above example, the tire deflection amount index is the contact length L, and the tire contact surface deformation range index is the deformation length X. However, the contact time and the deformation time may be used as they are. In this case, since a map that further considers the tire speed is necessary, it is preferable to set the length as a measure, as in this example, because stable estimation can be performed on one basis even if the speed fluctuates.
Further, the contact time ratio obtained by dividing the contact time by the time required for one rotation of the tire is used as an index of the amount of tire deflection, and the deformation time is divided by the time required for one rotation of the tire as an index of the tire out-of-plane deformation range. A deformation time ratio may be used. By using such a time ratio, as in the case where the length is used as a measure, even if the speed fluctuates, it is possible to perform stable estimation with one reference.
The tire deflection index is a tire circumferential acceleration waveform as shown in FIG. 7A or a time series waveform of values obtained by integrating radial acceleration as shown in FIG. 7B. The time interval between two peak values appearing in the integrated waveform of radial acceleration is measured and this is used as the contact time, and the contact length L, which is an index of tire deflection, is calculated from the contact time and tire speed. Good.

  In the above example, the wear of the tire is estimated from the tire radial acceleration detected by the acceleration sensor 11, but a strain sensor is provided instead of the acceleration sensor 11, and the tire circumferential strain waveform is detected to detect the tire wear. You may make it estimate. FIG. 8A is a diagram showing an example of a tire circumferential direction distortion waveform, and FIG. 8B is a differential waveform thereof. At the bulging point, as described above, the tire radial acceleration is positive and the tread is deformed to the outer side of the tire, but in that case, the inner surface of the tire is bent so as to be compressed with the belt as a neutral axis. The tire circumferential distortion is negative. Therefore, the time between the negative peaks of the tire circumferential distortion waveform may be measured and used as the deformation time. From the deformation time and the tire speed, the deformation length X that is an index of the deformation range outside the tire contact surface can be calculated. In addition, the point where the radial force changes most is the point where the tire circumferential strain also changes most. Therefore, the time between the two peaks appearing in the differential waveform of the tire circumferential strain waveform is measured to determine the contact time. Then, the contact length L that is an index of tire distortion can be calculated from the contact time and the tire speed.

  As described above, the tire wear estimation apparatus of the present invention is excellent in durability and can accurately detect tire wear regardless of the tire wear form. If the driver is made to recognize the vehicle, the driving safety of the vehicle can be improved.

It is a functional block diagram which shows the structure of the tire wear estimation apparatus which concerns on the best form of this invention. It is a figure which shows the example of attachment of an acceleration sensor. It is a figure which shows a tire radial direction acceleration waveform. It is a figure which shows the differential waveform of tire radial direction acceleration. It is a figure which shows the relationship between the contact length L and the deformation amount X. It is a schematic diagram which shows the external shape change of the tire at the time of a load load. It is a figure which shows the integrated waveform of a tire circumferential direction acceleration waveform and radial direction acceleration. It is a figure which shows the tire circumferential direction distortion waveform and the differential waveform of this distortion waveform.

Explanation of symbols

1 tire, 2 inner liner, 3 tire tread, 4 wheel,
10 tire wear estimation device, 11 acceleration sensor, 11F transmitter,
12 wheel speed sensors, 13 acceleration waveform extraction means, 14 differential waveform calculation means,
15 deformation length calculation means, 16 contact length calculation means, 17 storage means, 17M map,
18 Wear estimation means, 19 calculation unit.

Claims (13)

  Based on the input information from the sensor arranged in the tire tread portion, an index indicating the range of deformation of the tire tread portion outside the ground contact surface and an index indicating the amount of tire deflection at that time are calculated, and the calculated contact A tire wear estimation method, wherein the degree of wear of a tire is estimated from a relationship between an index of an out-of-ground deformation range and a tire deflection amount index.   The sensor is an acceleration sensor, and either a time series waveform of acceleration detected by the acceleration sensor, a time series waveform of a value obtained by differentiating the acceleration, or a time series waveform of a value obtained by integrating the acceleration The tire wear estimation method according to claim 1, further comprising: calculating an index of the out-of-ground surface deformation range and an index of tire deflection.   The tire wear estimation method according to claim 2, wherein the acceleration detection direction is a tire radial direction or a tire circumferential direction.   A time series waveform of tire circumferential strain detected by the strain sensor, a time series waveform obtained by differentiating the strain, or a time series waveform obtained by integrating the strain. 2. The tire wear estimation method according to claim 1, wherein an index of the out-of-ground surface deformation range and an index of tire deflection are calculated from any one of the above.   The tire wear estimation method according to any one of claims 2 to 4, wherein the sensor is arranged in an inner liner portion of the tire.   The deformation time, which is the time between two peaks corresponding to the deformation of the tread that appears in the time series waveform outside the contact surface, is calculated, and the deformation length obtained by multiplying the calculated deformation time by the tire speed is The tire wear estimation method according to any one of claims 2 to 5, wherein the tire wear estimation method is used as an index of a deformation range outside the tire contact surface.   A deformation time obtained by calculating a deformation time which is a time between two peaks corresponding to the deformation of the tread appearing in the time series waveform outside the ground contact surface, and dividing the calculated deformation time by a time required for one rotation of the tire. The tire wear estimation method according to any one of claims 2 to 5, wherein the time ratio is used as an index of the deformation range outside the tire contact surface.   The contact time, which is the time between two peaks corresponding to the deformation at the contact edge of the tread appearing in the time series waveform, is calculated, and the contact length obtained by multiplying the calculated contact time by the tire speed is the tire. 6. The tire wear estimation method according to claim 2, wherein the tire wear estimation method is used as an index of a deflection amount.   The contact time obtained by calculating the contact time, which is the time between two peaks corresponding to the deformation at the contact end of the tread appearing in the time series waveform, and dividing the calculated contact time by the time required for one rotation of the tire. The tire wear estimation method according to claim 2, wherein the ratio is used as an index of the tire deflection amount.   The tire wear estimation method according to any one of claims 1 to 9, wherein an upper limit value of a tire speed at which the degree of wear is estimated is set to 100 km / hr.   In accordance with the degree of tire wear, a relationship between an index representing the out-of-ground surface deformation range and an index representing the tire deflection at that time is obtained in advance, and the pre-determined index representing the out-of-ground surface deformation range. The degree of wear of the tire is estimated by comparing the relationship between the tire deflection amount and the tire deflection amount, and the relationship between the calculated out-of-ground surface deformation range index and the tire deflection amount index. The tire wear estimation method according to any one of claims 1 to 10.   An acceleration sensor that detects acceleration in the tire circumferential direction or tire radial direction of the tread portion and an index of the deformation range outside the contact surface of the tire from the peak corresponding to the tire bulging point of the time-series waveform of the detected acceleration. From the contact surface out-of-surface deformation range calculating means, differential waveform calculating means for calculating a differential waveform of acceleration, which is a time-series waveform of a value obtained by differentiating the acceleration, and a peak corresponding to the tire ground contact edge of the differential waveform of the acceleration Deflection amount calculating means for calculating an index of the amount of deflection of the tire, and a wear state estimating means for estimating the wear of the tire from the calculated index of the outside-surface deformation range and the index of deflection amount. A tire wear estimation device.   A strain sensor that detects the circumferential strain of the tread portion, and an out-of-ground surface that calculates an index of the tire's out-of-ground surface deformation range from the peak corresponding to the tire bulging point of the time-series waveform of the detected circumferential strain. Deformation range calculating means, differential waveform calculating means for calculating a differential waveform of circumferential distortion, which is a time-series waveform of a value obtained by differentiating the circumferential distortion, and a peak corresponding to the tire ground contact edge of the differential waveform of circumferential distortion A deflection amount calculating means for calculating an index of the deflection amount of the tire, and a wear state estimating means for estimating the wear of the tire from the calculated index of the deformation range outside the contact surface and the deflection amount index. A tire wear estimation device.

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