JP2011053027A - Tire wear estimation method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for estimating the wear condition of a running tire with high precision and its apparatus. <P>SOLUTION: The tire wear estimation method detects a vibration waveform of a tire 20 in which sipe rows 25A, 25B in which sipes 25a, 25b extending in the tire circumferential direction are arranged with a period of 2P, respectively, are formed on the right and left shoulder lands 24a, 24b by an acceleration sensor attached to a knuckle, performs rotational order analysis to determine a rotational order spectrum, determines a peak ratio R=(Z<SB>b</SB>/Z<SB>a</SB>), which is a ratio of a vibration level Z<SB>b</SB>of a rotational order N<SB>b</SB>corresponding to a period of P to a vibration level Z<SB>a</SB>of a rotational order N<SB>a</SB>corresponding to a period of 2P, compares the peak ratio R to a preset threshold R<SB>k</SB>, and estimates whether or not the wear of the tire 20 reaches a degree of warning wear. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

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 is greatly reduced 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.
Therefore, a technique for automatically detecting tire wear is required for warning the driver. 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, the tire resonance frequency component is extracted from the detection signal of the wheel speed sensor that detects the wheel rotation speed, and the wheel rotation speed and tire resonance frequency detected by the wheel speed sensor are extracted. There has been proposed a method for obtaining a tire wear amount based on a relationship between a difference in rotation speed of a wheel calculated from a resonance frequency of a tire obtained from a component (see, for example, Patent Document 1).

  On the other hand, the tire tread is embedded with a transponder, IC tag, etc., and a receiver is arranged on the vehicle body side. (For example, see Patent Documents 2 to 4), or an estimated body made of a magnetic material or conductive rubber is embedded in a tire tread, a sensor is disposed on the vehicle body side, and the estimated body is worn due to tire wear. There has been proposed a method of estimating the wear amount of a tire by detecting that the detection signal of the sensor changes due to wear (see, for example, Patent Documents 5 and 6).

Japanese Patent No. 3095095 JP-A-10-307981 JP 2004-205437 A US2002 / 0116992A1 JP 2003-214808 A JP 2005-28950 A

  However, in the method described in Patent Document 1, there is a limitation that sufficient data for calculating the resonance frequency cannot be obtained unless the wheel speed fluctuates to some extent and the state continues. There is a problem that implementation conditions are narrow. Further, since the relationship between the tire resonance frequency component and the wheel rotation speed is expected to vary depending on the tire type, the relationship between the tire resonance frequency component and the wheel rotation speed is determined in advance for each tire type. There was a need.

  On the other hand, in the method of embedding a transponder, an IC tag, or a magnetic material or conductive rubber, etc., disclosed in Patent Documents 2 to 6, since the wear progresses, the estimated body and sensor are exposed to the ground plane. Not only are there concerns about adverse effects on the durability of the tire, but there is a problem that the grip force of the tire is reduced when a rubber having physical properties different from that of the tread rubber is exposed on the surface of the tire tread.

  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 apparatus for accurately estimating the wear state of a running tire with a simple configuration.

In a tire in which a sipe is provided on the tread of the tire, when the sipe is in the ground contact surface, vibration (vibration in the tire width direction) due to wiping deformation occurs as the tire rolls. As a result of intensive studies, the inventor has provided two or more types of sipes having different depths periodically along the tire circumferential direction to detect the magnitude of the vibration corresponding to the cycle of the sipes generated in the tire. For example, when tire wear progresses and the shallow sipe disappears, the state of tire wiping deformation changes, and the vibration of the vibration component corresponding to the cycle also disappears. The inventors have found that the estimation can be performed with high accuracy and have arrived at the present invention.
That is, the invention according to claim 1 of the present application is a method for estimating the degree of wear of a tire, in which a plurality of recesses having different depths are arranged periodically along the tire circumferential direction of the tread. The vibration component corresponding to the period is extracted from the vibration of the tire, and the wear state of the tire is estimated from the magnitude of the vibration component.
Thereby, since the change of the wiping deformation | transformation state of a tire can be detected, the abrasion state of the tire during driving | running | working can be estimated accurately.
The concave portion may be a sipe or groove provided in a land portion of the tire, or may be a recess provided in a rib (a groove opening in a circumferential groove). Alternatively, it may be a lateral groove that partitions the block.

The invention according to claim 2 is the tire wear estimation method according to claim 1, characterized in that the depths of the adjacent recesses are different from each other.
Thereby, it is possible to estimate the degree of progress of wear with one row of recesses. Therefore, if this recess row is provided at a symmetrical position in the tire width direction around the center of the tire, the influence of uneven wear can be reduced.

According to a third aspect of the present invention, in the tire wear estimation method according to the first or second aspect, the concave portion is arranged in a shoulder portion of a tire where wiping deformation is significantly generated. Therefore, since a clearer vibration can be detected, the accuracy of wear estimation can be improved.
A fourth aspect of the present invention is the tire wear estimation method according to any one of the first to third aspects, wherein the recess is a sipe extending in the tire circumferential direction. Thereby, the recessed part from which groove depth differs can be formed easily.

According to a fifth aspect of the present invention, in the tire wear estimation method according to any one of the first to fourth aspects, the vibration of the tire is detected at a lower part of the vehicle spring.
Thereby, it is possible to accurately estimate the wear state of the running tire without providing a sensor on the tire. Further, since the sensor is not required to be attached to the tire, the tire production efficiency is improved. Further, the durability of the sensor can be improved as compared with the case where the sensor is mounted on the tire, and the sensor can be easily replaced.

The invention according to claim 6 is an apparatus for estimating a wear state of a running tire, in which a plurality of recesses having different depths are arranged periodically along the tire circumferential direction of the tread. Vibration detecting means for detecting the vibration of the tire, vibration component extracting means for extracting the vibration component corresponding to the period from the vibration of the tire, and means for estimating the wear state of the tire based on the magnitude of the vibration component It is characterized by having.
By adopting such a configuration, it is possible to accurately estimate the wear state of the running tire without providing a sensor in the tire portion.
A seventh aspect of the present invention is the tire wear estimation device according to the sixth aspect, wherein the vibration detecting means is installed under a vehicle spring.
Thereby, it is possible to accurately estimate the wear state of the running tire without providing a sensor in the tire portion.

According to an eighth aspect of the present invention, in the tire wear estimation device according to the sixth or seventh aspect, the estimated wear state of the tire is compared with a preset degree of wear to determine tire wear. Is provided with a judging means for judging whether or not the degree of wear exceeds the degree of wear.
This makes it possible to accurately determine whether or not tire wear has progressed.

The invention according to claim 9 is the tire wear estimation device according to claim 8, further comprising an alarm device that issues an alarm when the determination means determines that the degree of wear is exceeded. Features.
In this way, when the tire wear state exceeds a preset degree of wear, by issuing an alarm to the driver, the driver can be urged to change the tire, etc. Can be improved.

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

It is a functional block diagram which shows the structure of the tire wear estimation apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the tread pattern of the tire in which the periodic sipe row | line | column which concerns on this Embodiment was formed. It is a figure which shows an example of the tread pattern of the tire at the time of wear progress. It is a figure which shows an example of the rotation order spectrum obtained by analyzing rotation order ratio analysis of the vibration of a vehicle spring lower part. It is a figure which shows the other example of the recessed part extended along the tire circumferential direction formed in the tread of the tire by this invention. It is a figure which shows the other example of the tread pattern of the tire in which the periodic sipe row | line | column by this invention was formed.

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

FIG. 1 is a functional block diagram showing a configuration of a tire wear estimation device 10 according to the present embodiment. The tire wear estimation device 10 includes an acceleration sensor 11 as vibration detection means and a wheel speed sensor as rotation speed detection means. 12, a rotation signal generation unit 13, a rotation order ratio analysis unit 14, a storage unit 15, a rotation order component extraction unit 16, a wear state estimation unit 17, and an alarm unit 18.
As shown in FIG. 2, the tire 20 of the present invention includes circumferential grooves 22a to 22d extending in the tire circumferential direction, circumferential grooves 22a and 22b, circumferential grooves 22b and 22c, and circumferential grooves 22c and 22d. Rib-shaped central land portions 23a, 23b, and 23c that are partitioned, and left and right shoulder land portions 24a and 24b that are positioned on the outer side in the tire width direction of circumferential grooves (shoulder grooves) 22a and 22d that are positioned on the outer side in the tire width direction It has.

The left and right shoulder land portions 24a and 24b are respectively provided with sipe rows 25A and 25B in which sipes 25a and 25b extending in the tire circumferential direction are periodically arranged along the tire circumferential direction over the entire circumference of the tire. ing.
The distance from the tire center CL to the sipe row 25A is equal to the distance from the tire center CL to the sipe row 25B. On the other hand, they are different from each other and the depth D _b of the depth D _a and sipes 25b of the sipe 25a. In this example, D _a > D _b .
In both the sipe row 25A and the sipe row 25B, the sipe 25a and the sipe 25b are provided alternately along the tire circumferential direction, and the distance between the sipe 25a and the sipe 25b along the tire circumferential direction and the sipe The distance between the tire 25b and the sipe 25a along the tire circumferential direction is the same. Assuming that this interval is P, the sipe 25a is arranged at a cycle 2P, and the sipe 25b is arranged from the sipe 25a by the interval P in the tire circumferential direction, and is arranged at the same cycle 2P as the sipe 25a.
That is, in the tire 20 of the present invention, the pattern pitch number N _a = (2πR ₀ ) / 2P and the pattern pitch number N _b = (2πR ₀ ) / (2P) 2 on the left and right shoulder land portions 24a and 24b. Has one periodic pattern. R ₀ is the radius of the tire when it is new.
In the present invention, since the purpose is to estimate the wear of the tire 20, hereinafter, the periodic pattern is represented not by the period but by the number of pattern pitches.

As shown in FIG. 1, the acceleration sensor 11 is attached to the knuckle 31 and detects vibration of the tire 20 (hereinafter referred to as tire vibration) transmitted to the knuckle 31 through the wheel 32 and the wheel hub 33. The detection direction of the acceleration sensor 11 is the tire width direction.
The knuckle 31 is a non-rotating side part (vehicle unsprung part) of the wheel unit 30 connected via a bearing to a wheel hub 33 that rotates together with a wheel 32 on which the tire 20 is mounted. Is installed. The knuckle 31 is connected to upper and lower arms 35 and 36 of a vehicle suspension system provided with a suspension member 34 via buffer members 37 and 38 such as rubber bushes.
If the acceleration sensor 11 is attached to a member such as the upper and lower arms 35 and 36 connected to the wheel 32 via the buffer members 37 and 38, the vibration of the tread 21 is caused by the damper effect of the buffer members 37 and 38. Detection accuracy decreases. Therefore, even when the acceleration sensor 11 is attached to the lower part of the vehicle spring, vibrations transmitted from the tire 20 to the lower part of the vehicle spring can be accurately detected when the acceleration sensor 11 is installed on the wheel 32 side of the buffer members 37 and 38. can do.

The wheel speed sensor 12 detects the rotational speed of the wheel (hereinafter referred to as the wheel speed). In this example, a rotor that has a gear formed on the outer peripheral portion thereof and rotates together with the wheel, a yoke that constitutes the rotor and a magnetic circuit, and And a coil for detecting a change in magnetic flux of the magnetic circuit, and a known electromagnetic induction type wheel speed sensor for detecting the rotation angle of the wheel is used. The yoke and the coil are attached to the knuckle 31. As the wheel speed sensor 12, a wheel speed sensor having another configuration such as a combination of a ring multipolar magnet and a magnetoresistive element may be used. Alternatively, the rotational speed of a transmission (not shown) may be detected and used as the wheel speed.
The rotation signal generator 13 generates and outputs a pulse signal that rises at the zero cross point of the output of the wheel speed sensor 12. The number of pulses generated by one rotation of the tire is twice the number of gears of the rotor or the number of magnetic poles of the ring multipole magnet. Therefore, the wheel speed can be detected by counting the number of pulses, and the pulse signal output from the rotation signal generating means 13 can be used as a sampling clock. Since the sampling clock is synchronized with the rotational speed, if the tire vibration detected by the acceleration sensor 11 is sampled using this sampling clock, the number of samples per tire rotation is constant regardless of the wheel speed. However, in terms of time, the sampling interval becomes narrower as the wheel speed becomes slower, and becomes wider as the wheel speed becomes faster.

The rotation order ratio analysis unit 14 includes a low-pass filter 14a, a sampling unit 14b, and an analysis unit 14c.
The low-pass filter 14a removes high-frequency components of vibration in the tire width direction of the tire 20 detected by the acceleration sensor 11, and suppresses the occurrence of aliasing phenomenon (turnback) in the rotation order ratio analysis.
The sampling unit 14 b samples the tire vibration detected by the acceleration sensor 11 using the sampling clock output from the rotation signal generation unit 13.
The analyzing unit 14c performs FFT processing on the sampled tire vibration vibration waveform to obtain a vibration spectrum. The horizontal axis of the vibration spectrum (frequency spectrum) of the vibration waveform measured at a constant time interval is the frequency, whereas the horizontal axis of the vibration spectrum of the vibration waveform measured at a constant rotation interval is the rotation order (Order) n. Hereinafter, this vibration spectrum is referred to as a rotation order spectrum.

The storage means 15 uses the rotation used for estimating the tire wear out of the rotation order of the tire vibration corresponding to the periodic spectrum of the sipe trains 25A and 25B obtained from the tread pattern design drawing of the tire 20 to be used shown in FIG. Save the orders N _a and N _b .
The rotation order N _a is equal to the above-described pattern pitch number, and N _a = (2πR ₀ ) / 2P, and the rotation order N _b is N _b = (2πR ₀ ) / (P). In this example, N _b = 2N _a .
The rotation order component extraction unit 16 extracts a peak vibration level corresponding to the rotation order N _a and a peak vibration level corresponding to the rotation order N _b from the rotation order spectrum obtained by the rotation order ratio analysis unit 14.

In the tire 20 of the present invention, even in the sipe row 25B even sipe row 25A, since the depth D _a of the sipe 25a is formed deeper than the depth D _b of the sipe 25b, tread wear 21 is developed When sipes 25b disappears, sipe rows 25A, 25B are both, as shown in FIG. 3, the number of pattern pitch becomes sipe sequence of N _a.
That is, the sipe when the tire 20 is new, the left and right shoulder land portion 24a, the 24b, sipes number pattern pitch has a periodic pattern of N _a of (sipe 25a) and the pattern pitch number has a periodic pattern of N _b ( There is a sipe having two periodic patterns of sipe 25b), but when wear progresses, there is only a sipe having _a periodic pattern with _a pattern pitch number Na. Therefore, if the vibration component corresponding to the number of pattern pitches is extracted from the vibration of the tire 20 and the wear state of the tire is estimated from the size of the extracted vibration component, the tire wear state can be reliably estimated. .

FIG. 4 shows a vehicle measured by running a vehicle equipped with a tire mounted by grinding the tread 21 of the tire 20 until the sipe 25b disappears, as measured by running the vehicle carrying the tire 20 It is a figure which shows the rotation order spectrum obtained by analyzing each rotation order ratio analysis with the vibration of a spring lower part. The thin solid line in the figure is a new tire (hereinafter referred to as a new model tire), and the thick solid line is a rotational order spectrum of a tire after grinding (hereinafter referred to as a wear model tire).
17 order peak shown by the arrow in the figure, the peak corresponding to 17 times the vibration in rotating the tire 1 is generated, a peak number of pattern pitches corresponding to N _a. Moreover, 34-order peaks, the peak corresponding to 34 times the vibration in rotating the tire 1 is generated, a peak number of pattern pitches corresponding to N _b.
In addition, when the tire vibration detected by the acceleration sensor 11 is sampled at a constant time interval, the rotation interval becomes non-uniform due to speed fluctuation, but Lomb-Scargle Periodgram (Scargle JD 1982, The Astrophysical Journal, 263, 835), a rotation order spectrum can be obtained without sampling at a constant rotation interval by using a method for estimating a vibration spectrum from data sampled at non-uniform intervals.

The wear state estimation means 17 includes a peak ratio calculation unit 17a and a determination unit 17b.
Peak ratio calculation unit 17a is the ratio of the vibration level Z _b peaks corresponding to the rotational order component N _b for vibration level Z _a peak corresponding to the rotational order component N _a extracted by rotational order component extracting unit 16 The peak ratio R = (Z _b / Z _a ) is obtained.
The determination unit 17b compares the peak ratio R with a preset threshold value R _k and estimates the wear state of the tire 20 during traveling. The threshold value R _k is a value of a peak ratio corresponding to a preset degree of wear of the tire 20 (hereinafter, warning wear degree), and in this example, R _k = 1/5.
Wear state estimating means 17, at the stage where the peak ratio R becomes the threshold R _k, and sends a signal that the wear state of the tire 20 has reached the warning wear degree to the alarm means 18.
The alarm means 18 is installed in the vicinity of the driver's seat, and when a signal indicating that the tire wear state has reached the warning wear level is inputted, the driver wears the tire by lighting or flashing an alarm LED. Recognize the state. Note that the alarm buzzer may be driven and recognized by an alarm sound, or the alarm buzzer and the LED may be used in combination.

Next, a tire wear estimation method according to the present embodiment will be described.
First, a tire 20 in which sipe rows 25A and 25B in which sipes 25a and 25b extending in the tire circumferential direction are arranged in a cycle 2P is formed on the left and right shoulder land portions 24a and 24b is attached to the wheel 32, and the knuckle 31 is attached. The vibration of the tire 20 is detected by the attached acceleration sensor 11, and the wheel speed is detected by the wheel speed sensor 12. The acceleration sensor 11 detects a time-series waveform (hereinafter referred to as a vibration waveform) of the vibration in the tire width direction of the tire 20 transmitted to the lower part of the vehicle spring.
Next, the vibration waveform of the tire 20 is subjected to a rotational order ratio analysis by the rotational order ratio analyzing means 14 to obtain a rotational order spectrum having the horizontal axis as the rotational order as shown in FIG.
The rotation order spectrum is obtained by sampling the tire vibration detected by the acceleration sensor 11 based on the wheel speed data output from the rotation signal generating means 13 and the wheel speed pulse signal, and then performing FFT processing.
By rotation order component extracting unit 16, a vibration level Z _a is the peak value of the vibration of the rotational order N _a corresponding to the period 2P, the vibration level is the peak value of the vibration of the rotational order N _b corresponding to the period P Z _b is extracted.

As the wear of the tire 20 progresses, the peak corresponding to the rotational order component N _b gradually decreases, and accordingly, the peak ratio R = (Z _b / Z _a ) also decreases. When the same amount and wear depth D _b of the sipe 25b progresses, the peak corresponding to the rotational order component N _b is lost, the peak ratio R is substantially zero (noise level).
Therefore, the wear state estimation means 17 obtains the peak ratio R = (Z _b / Z _a ) and compares the peak ratio R with a preset threshold value R _k , so that the peak ratio R becomes the threshold value R _k . At this stage, a signal indicating that the wear state of the tire 20 has progressed and the degree of warning wear has been reached is sent to the alarm means 18, and the warning LED is turned on or blinked to alert the driver of tire wear. Recognize that the degree has been reached.

As described above, in the present embodiment, the acceleration sensor 11 attached to the knuckle 31 has a sipe row 25A in which the sipe 25a and 25b extending in the tire circumferential direction are arranged on the left and right shoulder land portions 24a and 24b with a period of 2P. , 25B obtains the rotational order spectrum rotates harmonic analysis to detect the vibration waveform of the tire 20 is formed, the rotational order N _b corresponding to the period P for the vibration level Z _a of the rotational order N _a corresponding to the period 2P The peak ratio R = (Z _b / Z _a ), which is the ratio of the vibration level Z _b , is obtained, and the peak ratio R is compared with a preset threshold value R _k , so that the wear of the tire 20 reaches the warning wear level. Therefore, it is possible to accurately estimate the wear state of the running tire 20.
In addition, when it is estimated that the wear of the tire 20 has reached the warning wear level, an alarm is issued so that the driver can recognize this, so that the traveling safety of the vehicle can be improved.

In the above-described embodiment, the tire 20 is a tire in which the left and right shoulder land portions 24a and 24b are respectively formed with the sipe rows 25A and 25B having a period of 2P. However, only the one shoulder land portion 24b is used. A sipe train 25B having a period P may be provided. However, from the viewpoint of running stability, it is preferable to provide sipe rows on the left and right shoulder land portions 24a and 24b as in this example.
In the above example, the progress of wear of the tire 20 is estimated using the peak ratio R = (Z _b / Z _a ), but with respect to the vibration level Z _b corresponding to the rotational order N _b corresponding to the period P. A threshold value K _b may be provided, and it may be estimated that the wear of the tire 20 has progressed when the vibration level Z _b becomes less than the threshold value K _b .

Moreover, as a recessed part extended along a tire circumferential direction, it is not restricted to the sipe 25a, 25b provided in the left and right shoulder land part 24a, 24b, As shown to Fig.5 (a), the shoulder land part 24a or The grooves 26a and 26b provided in the shoulder land portion 24b may be used, or the grooves 27a and 27b opened in the circumferential groove 22a or the circumferential groove 22d as shown in FIG. .
However, also in this case, the depth of the groove 26b (or the groove 27b) is set to the reference depth for the progress of wear, and the depth of the groove 26b is shallower than the depth of the groove 26a (or the groove 27a). It goes without saying that it is set.
Moreover, as a recessed part extended along a tire circumferential direction, the lateral grooves 28a and 28b which divide the shoulder block 24B as shown in FIG.5 (c) may be sufficient. Also in this case, the depth of the lateral groove 28b is set to the reference depth of wear progress, and the depth of the groove 28b is set to be shallower than the depth of the groove 28a.

In the above example, the sipe depth is two types (D _a , D _b ; D _a > D _b ), but may be three or more types. Thus, the degree of wear progress can be set more finely by increasing the types of sipe depth.
Further, in the above example, the same sipe rows 25A and 25B are provided in the shoulder land portions 24a and 24b, respectively, but as shown in FIG. 6, the sipe 25a having _a depth Da is formed in the left shoulder land portion 24a. May be arranged with a period P in the tire circumferential direction, and sipes 25b having _a depth of D _b (D _a > D _b ) may be arranged with a period Q in the tire circumferential direction on the right shoulder land portion 24b. However, in this case, since the shape of the tread 21 is not targeted with respect to the tire center CL, it is preferable to provide the same sipe rows 25A and 25B on the left and right shoulder land portions 24a and 24b as in this example. This is preferable from the viewpoint of running stability.

  In the above example, the sampling clock generated by sending the output of the wheel speed sensor 12 to the rotation signal generation means 13 is output to the rotation order ratio analysis means 16, but the vehicle control means has a CAN (controller area In a vehicle in which a network is formed, the wheel speed is preferably acquired from CAN. Thereby, an apparatus can be made simpler.

In the above example, the rotational order spectrum has been determined and the vibration level Z _b of the rotational order N _b corresponding to the vibration level Z _a and the period P of the rotational order N _a corresponding to the period 2P, from the acceleration sensor 11 obtains a frequency spectrum by FFT processing vibration waveform of tire vibration outputted from this frequency spectrum, the vibration component of the frequency f _b corresponding to vibration component Y _a and the period P of the frequency f _a corresponding to the period 2P Y _b And the wear state of the tire 20 may be estimated. However, in this case, the frequency f _a and the frequency f _b, so varies with the wheel speed, the frequency f _a and the frequency f _b, it must be calculated by using the period P _a and the period P _b and the wheel speed is there.

A tire was produced in which 34 circumferential sipes having a length of 20 mm were formed on the left and right shoulders of a tire having a tire size of 225 / 55R17 over the entire circumference and evenly. The depth of the circumferential sipe was 5 mm, 8 mm, 5 mm, 8 mm, and so on alternately.
In order to reproduce tire wear in a simulated manner after mounting the tire wear estimation device according to the present invention on a vehicle equipped with this tire (new tire) and measuring the unsprung vibration in the tire width direction by running this vehicle, A wear simulation tire with a 5 mm shaved tread was mounted on the vehicle again and the vehicle was run to measure unsprung vibration in the tire width direction. In the simulated wear tire, the sipe that was 5 mm deep disappeared, but the sipe that was 8 mm deep when new is still a sipe with a depth of 3 mm.
After the test, the rotation order spectrum of the unsprung vibration of the new tire and the simulated wear tire was analyzed to obtain the rotation order spectrum.
In the rotational order spectrum of the new tire shown by the thin solid line in FIG. 4, vibration peaks occurred in the vicinity of the 17th rotational order and the 34th rotational order, but the wear simulation product tire shown by the thick solid line in FIG. In the rotation order spectrum, the peak around the 34th order of the rotation order disappears, and only the vibration peak remains around the 17th order of the rotation order. Thus, it was confirmed that the progress of wear could be estimated by detecting the disappearance of the peak near the 34th order.

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

  As described above, according to the present invention, the wear of a running tire can be accurately estimated, so that it is possible to improve the running safety of the vehicle, such as issuing a warning in the rain or prompting the tire to be replaced. Can do.

10 tire wear estimation device, 11 acceleration sensor, 12 wheel speed sensor,
13 rotation signal generation means, 14 rotation order ratio analysis means, 14a low-pass filter,
14b sampling means, 14c analysis means, 15 storage means,
16 rotational order component extraction means, 17 wear state estimation means, 17a peak ratio calculation section,
17b determination unit, 18 alarm means,
20 tires, 21 treads, 22a-22d circumferential grooves,
23a-23c Central land part, 24a, 24b Shoulder land part,
25A, 25B Sipe train, 25a, 25b Sipe,
30 wheel part, 31 knuckle, 32 wheel, 33 wheel hub,
34 Suspension member, 35, 36 Arm, 37, 38 Buffer member.

Claims (9)

  Detecting vibration of a tire in which a plurality of recesses having different depths are periodically arranged along the tire circumferential direction of the tread, extracting a vibration component corresponding to the period from the vibration of the tire, A tire wear estimation method characterized by estimating a wear state of a tire from a size.   The tire wear estimation method according to claim 1, wherein the depths of adjacent recesses are different from each other.   The tire wear estimation method according to claim 1, wherein the recess is disposed in a shoulder portion of the tire.   The tire wear estimation method according to any one of claims 1 to 3, wherein the recess is a sipe extending in a tire circumferential direction.   The tire wear estimation method according to any one of claims 1 to 4, wherein vibration of the tire is detected at a lower part of a vehicle spring. Vibration detecting means for detecting the vibration of the tire in which a plurality of recesses having different depths are periodically arranged along the tire circumferential direction of the tread;
Vibration component extracting means for extracting a vibration component corresponding to the cycle from the vibration of the tire;
A tire wear estimation device comprising: means for estimating a tire wear state based on the magnitude of the vibration component.   The tire wear estimation device according to claim 6, wherein the vibration detection means is installed under a vehicle spring.   The tire wear condition of the tire is compared with a preset degree of wear, and a judging means for judging whether or not the tire wear exceeds the degree of wear is provided. The tire wear estimation device according to claim 6 or 7.   The tire wear estimation device according to claim 8, further comprising a warning device that issues a warning when the determination unit determines that the degree of wear is exceeded.

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