JP2005206145A - Tire abnormality detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire abnormality detection device capable of detecting local abnormality of a tire with high reliability by using a sensor which detects physical quantity changing in accordance with rotation of a rotor mounted on a wheel. <P>SOLUTION: The wheel sensor 2 to detect the physical quantity is mounted on an axle pipe to axially support the wheel through a coil spring 6 and characteristic frequency of the coil spring 6 is made to match secondary characteristic frequency of the tire on the tire abnormality detection device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tire abnormality detection device that detects a local abnormality of a running tire, and particularly relates to a tire having a highly reliable detection performance.

  As a device for detecting local abnormalities of running tires, for example, signs of failure such as separation, it is attached to a wheel and rotates around its central axis, and the physical quantity at a predetermined position is periodically changed by the rotation. A rotating body that is attached to an axle that pivotally supports the wheel, a sensor that continuously detects the physical quantity and outputs a signal corresponding to the physical quantity, and a period of rotation of the rotating body from the output signal of the sensor There is known a tire abnormality detection device including signal processing means for extracting a vibration component caused by a local abnormality of a tire superimposed on a typical component (see, for example, Patent Document 1). As an example, there is a combination of a gear pulser that constitutes an ABS signal generator and a wheel sensor that detects a change in magnetic field accompanying rotation of the gear pulser.

The signal processing means is configured to extract a change in the physical quantity due to vibration of the rotating body caused by a local abnormality of the tire superimposed on a periodic change in physical quantity due to the rotation of the rotating body. This utilizes the fact that a vibrational change appears in the rotation of the rotating body due to a mechanical abnormality. However, in practice, this change is slight, especially when extracting this change by comparing with the adjacent wheels of the same vehicle, or by comparing with the state of the tires of the own wheels that are not abnormal. However, there is a problem that the detection is very delicate and the reliability of abnormality detection is low and not practical.
JP 2003-146036 A

  The present invention has been made in view of such problems, and a local abnormality of a tire is detected with high reliability by using a sensor that detects a physical quantity that changes due to rotation of a rotating body attached to a wheel. An object of the present invention is to provide a tire abnormality detection device that can detect.

<1> is attached to a wheel and rotates about its central axis, and is attached to a rotating body that periodically changes a physical quantity at a predetermined position by the rotation, and an axle that supports the wheel, and the physical quantity is continuous. Sensor that automatically detects and outputs a signal corresponding to this physical quantity, and extracts the vibration component caused by local abnormality of the tire superimposed on the periodic component due to the rotation of the rotating body from the output signal of this sensor In a tire abnormality detection device comprising signal processing means for
A tire abnormality detection device in which the sensor is attached to the non-rotating portion of the axle via an urging means.

  <2> In <1>, the rotating body is configured by a gear pulser made of a magnetic material having a high magnetic permeability, and the sensor is detected by a permanent magnet and a magnetic field from the permanent magnet that changes as the gear pulser rotates. It is a tire abnormality detection device comprising a coil for generating an electromotive force.

  In <3>, in <1>, the rotating body is configured with a permanent magnet in which N poles and S poles are alternately arranged in a circumferential direction at a predetermined pitch, and the sensor is rotated along with the rotation of the permanent magnet. It is a tire abnormality detection device configured by a magnetic sensor that detects a changing magnetic field.

  <4> is any one of <1> to <3>, wherein the signal processing means is means for extracting only a rotational correlation signal correlated with wheel rotation from an output signal of the sensor using an adaptive digital filter. , A tire abnormality detection device configured to include abnormality determination means for determining a local abnormality of the tire from the rotational correlation signal.

  <5> is the tire abnormality detection device according to any one of <1> to <4>, wherein the natural frequency of the urging means is made to coincide with the natural frequency of the tire.

  <6> is the tire abnormality detection device according to any one of <1> to <4>, wherein the natural frequency of the urging means is made to coincide with the secondary natural frequency of the tire.

  <7> is a tire abnormality detection device according to any one of <1> to <4>, wherein the sensor is provided with a damping material that attenuates a signal amplitude at a natural frequency of the biasing means.

  According to the invention <1>, since the sensor for detecting the physical quantity change due to the rotation of the rotating body is attached to the axle via the biasing means, the local abnormality of the tire is a vibrational change in the rotation of the rotating body. In addition to causing vibration, the vibration force on the axle amplifies the displacement of the sensor supported by the biasing means such as a spring, and a large vibration component in the physical quantity that changes depending on the relative position between the rotating body and the sensor. This facilitates the extraction of the vibration component caused by the local abnormality of the tire superimposed on the periodic component due to the rotation of the rotating body, and detects the local abnormality of the tire with high reliability. Can do.

  According to the invention <2>, the wheel sensor comprising the gear pulsar, the permanent magnet, and the detection coil constituting the ABS signal generator, the wheel sensor that detects a change in the magnetic field accompanying the rotation of the gear pulsar. Therefore, the invention <1> can be easily realized, and the cost of the apparatus can be reduced by using the existing ABS signal generator as the rotating body and the sensor.

  According to the invention <3>, since the rotating body and the sensor are constituted by a permanent magnet that generates an alternating magnetic field in the circumferential direction and a magnetic sensor such as an MR sensor that detects the magnetic field, The invention can be easily realized, the change of the magnetic field itself can be directly detected, and the subsequent processing by the signal processing means can be simplified.

  According to the invention of <4>, the signal processing means uses the adaptive digital filter to extract only the rotation correlation signal correlated with the rotation of the wheel from the output signal of the sensor, and the tire based on the rotation correlation signal Therefore, irregular vibrations caused by road surface conditions and driving conditions can be excluded, and the reliability in detecting tire abnormality can be improved.

  According to the invention <5>, the natural frequency of the urging means is made to coincide with the natural frequency of the tire, so that the amplitude is amplified by resonance, and it is easy to extract the vibration component due to the local abnormality of the tire. Thus, local abnormality of the tire can be detected with high reliability.

  According to the invention <6>, since the natural frequency of the biasing means is matched with the secondary natural frequency of the tire, the amplitude is amplified by resonance, and the vibration component caused by local abnormality of the tire Extraction is easy, and local abnormality of the tire can be detected with high reliability, and the biasing means is too soft when the natural frequency of the biasing means coincides with the primary natural frequency of the tire. The problem that the sensor part comes into contact with the gear pulser and the problem that the amplitude is too small when the natural frequency of the urging means matches the natural frequency of the third or higher order of the tire can be solved.

  According to the invention <7>, since the vibration damping material for attenuating the signal amplitude at the natural frequency of the biasing means is provided in the sensor, the signal vibration caused by road surface unevenness is quickly converged, and the tire It is possible to easily discriminate a signal output once per rotation and to detect a local abnormality of the tire with higher reliability.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a layout diagram showing the configuration of a tire abnormality detection device. The tire abnormality detection device 10 is attached to a wheel on which a tire T is mounted and rotates around a central axis of the wheel. Each wheel sensor 2 mounted on an axle that supports the wheel corresponding to the gear pulser 1 and a signal for processing the output signals from these wheel sensors 2 and extracting vibration components caused by local abnormality of the tire Based on the output from the processing means 3 and the signal processing means 3, a display alarm device 4 for displaying a tire abnormality or issuing an alarm is provided.

  FIG. 2 is a cross-sectional view showing how the gear pulsar 1 and the wheel sensor 2 are attached, and FIG. 3 is a schematic view showing the detection principle of the wheel sensor 2. The hub 8 that supports the tire T via the wheel W has a hub central shaft portion 8 </ b> A that is pivotally supported on the outer side in the radial direction of the axle pipe 9 and is disposed in the hollow portion of the axle pipe 9. The gear pulser 1 made of a magnetic material having a high magnetic permeability is attached around the hub central shaft portion 8A and rotates integrally with the hub 8. On the other hand, the wheel sensor 2 is a coil spring 5 constituting an urging device. Is attached to the inner peripheral surface of the axle pipe 9 and is disposed so as to face the gear pulser 1 from the outside in the radial direction.

  The wheel sensor 2 includes a permanent magnet 7 that generates a magnetic field and a magnetic field detection coil 14 that generates an electromotive force in accordance with a change in the magnetic field formed by the permanent magnet 7. In order to strengthen the magnetic field in the coil 14, a core 14 a made of a high permeability magnetic material is provided at the center of the magnetic field detection coil 14.

  When the gear pulsar 1 rotates with the rotation of the wheel, the teeth 1a disposed at a predetermined pitch around the gear pulsar 1 repeatedly move away from the permanent magnet and are disposed between the magnet and the gear pulsar 1. The number of lines of magnetic force passing through the core 14a of the magnetic field detection coil 14 is repeatedly increased and decreased, and the frequency of this repetition is proportional to the rotational speed of the axle. Therefore, the rotational speed of the axle can be obtained by measuring this frequency. Such a combination of the gear pulsar 1 and the wheel sensor 2 is already used as an ABS signal generator. In the present invention, the gear pulser 1 and the wheel sensor 2 are conventionally fixed to the axle pipe 9 serving as an axle non-rotating portion. The wheel sensor 2 attached in this manner is characterized in that it is attached to the axle pipe 9 via the coil spring 5. In the illustrated example, the coil spring 5 is configured to bear only the vertical load of the wheel sensor 2 by providing the linear motion guide 6.

  The tire abnormality detection device 10 detects an abnormality by extracting a vibration component caused by a local abnormality of the tire from various vibration components superimposed on a periodic component due to the rotation of the gear pulser 1. The vibration component resulting from the local abnormality of the tire is superimposed as follows. FIG. 4 is a graph showing the magnetic field strength detected by the magnetic field detection coil 14 on the vertical axis and time on the horizontal axis, and shows the temporal change of the magnetic field. FIG. 4A shows the gear pulser 1. The magnetic field change CV1 in the case where there is no disturbance of only a periodic component due to the rotation of is shown.

  When a precursor of abnormality such as tread separation occurs locally in the running tire, a change appears in the periodic rotation of the gear pulser 1 at the timing when the tire portion corresponding to this abnormality contacts the road surface, for example, As shown in FIG. 4B, the peak width of a part of the magnetic field change CV1 becomes wide, and this part becomes a magnetic field change replaced by CV2. Further, when the abnormal portion of the tire is grounded, the abnormal portion vibrates the axle pipe 9, but the wheel sensor 2 is supported by the coil spring 5 and attached to the axle pipe 9. This vibration vibrates the position relative to the gear pulser 1, and thus a magnetic field change as shown by CV3 in FIG. 4C appears.

  In order for the tire abnormality detection device 10 to detect an abnormality in the tire T, the signal processing means 3 must function so as to extract the difference between the original magnetic force change and at least one of CV2 and CV3 in FIG. However, if the wheel sensor 2 is directly attached to the axle pipe 9 without the coil spring 5, the CV3 does not appear, and the CV2 is almost the same as the CV1. It is difficult to extract. In the present invention, in addition to CV2, by generating CV3 that can be clearly distinguished from the original magnetic force change CV1, a local abnormality in the tire can be more faithfully reflected as a magnetic force change. Reliability can be greatly improved.

  Next, a method for extracting vibration components caused by local abnormality of the tire with higher reliability will be described. In the first method, the natural frequency of the tire and the natural frequency of the coil spring are matched, and the amplitude is amplified by resonance and extracted. When the local abnormality of the tire is small, the change in the signal is small and the change in the physical quantity is difficult to detect, but by matching the natural frequency of the tire with the natural frequency of the coil spring and amplifying the amplitude by resonance, A vibration component caused by a local abnormality of the tire can be easily extracted.

  Table 1 shows an example of the natural frequency of the tire. The natural frequency of the tire varies depending on the rubber material and the like. For example, the natural frequency of a tire having a tire size of 275 / 70R16 is generally as shown in Table 1.

The front-rear direction natural frequency is the natural frequency of the tire when a vibration force is applied to the tire in the front-rear direction of the wheel. The vertical direction natural frequency is the vibration force applied to the tire in the vertical direction of the wheel. It is the natural frequency of the tire when given, and the natural frequency in the front-rear direction is the natural frequency of the tire when an excitation force is applied to the tire in the left-right direction of the wheel.

  It is preferable to make the natural frequency of the coil spring coincide with the natural frequency of the tire having a small order because the amplitude becomes large. However, when trying to make the natural frequency of the coil spring coincide with the primary natural frequency, The elastic modulus must be lowered. However, if it is too low, that is, if it is too soft, there is a problem that the sensor part comes into contact with the gear pulser. Further, when the natural frequency of the coil spring is matched with the natural frequency of the third or higher order, the amplitude is too small, and furthermore, the primary cavity resonance frequency of the tire is around 250 Hz, so it is desirable to avoid the vicinity of this frequency. From these facts, it is most preferable to match the natural frequency of the coil spring with the secondary natural frequency of the tire.

  Therefore, when the sensor is attached to the axle so as to vibrate in the longitudinal direction of the wheel, the natural frequency of the coil spring is matched with the secondary natural frequency (60 to 100 Hz) of the tire in the longitudinal direction. When mounted on the axle so as to vibrate in the vertical direction of the wheel, the natural frequency of the coil spring is matched with the secondary natural frequency (140-220 Hz) of the tire in the vertical direction, and the sensor is in the horizontal direction of the wheel. In the case of being attached to the axle so as to vibrate in the horizontal direction, it is preferable to match the natural frequency of the coil spring with the secondary natural frequency (80 to 120 Hz) of the tire in the left-right direction.

  The largest signal amplitude can be obtained when the sensor is attached to the axle so as to vibrate in the vertical direction of the wheel and the natural frequency of the coil spring is matched with the natural frequency of the tire in the vertical direction. Further, when an existing ABS signal generator is used as a gear pulser and a sensor, the ABS signal generator sensor is generally configured such that the line segment direction connecting the N pole and the S pole of the sensor is the front-rear direction of the wheel. Therefore, the natural frequency of the coil spring is made to coincide with the natural frequency of the tire in the front-rear direction.

  In the second method, the wheel sensor is provided with a damping material that attenuates the signal amplitude at the natural frequency of the coil spring, and is output once per rotation of the tire when the tire has, for example, one local abnormality. The signal can be extracted. On rough roads, if a large vibration is applied to the tire due to road surface irregularities, the amplitude of the transient response will continue to swing, causing the signal amplitude due to road surface irregularities and the tire to rotate once due to local abnormalities in the tire. It becomes impossible to distinguish the signal amplitude output once. Therefore, the wheel sensor is provided with a damping material to reduce the signal amplitude at the natural frequency of the tires, suspension parts, and coil springs that support the wheel sensor, and the amplitude of the signal vibration caused by road irregularities appearing aperiodically. Thus, a signal output once per rotation of the tire, which is a signal correlated with tire abnormality, can be discriminated.

  FIG. 5 is a schematic diagram showing an example in which the wheel sensor is provided with a damping material. The wheel sensor 2 includes a permanent magnet 7 that generates a magnetic field, a magnetic field detection coil 14 that generates an electromotive force according to a change in the magnetic field formed by the permanent magnet 7, and a coil 14 that strengthens the magnetic field in the coil 14. The core 14a made of a high permeability magnetic body provided at the center of the coil and the damping material 25 that suppresses the vibration of the coil spring 5 are configured. Further, a metal weight 26 for adjusting the natural frequency of the coil spring is attached to the coil spring 5, and the wheel sensor 2 is attached to the axle pipe 9 via the coil spring 5 to which the weight 26 is attached. ing. The coil spring 5 is configured to bear only the load in the vertical (up and down) direction of the wheel sensor 2 with the linear motion guide 6.

  As the vibration damping material 25, viscoelasticity, that is, a rubber-based, plastic-based, or asphalt-based compound material having tan δ = 0.01 to 1.0 is used. In FIG. 5, the damping material is provided on the gear pulser 1 side of the wheel sensor 2, but may be provided on any part of the wheel sensor 2 including the coil spring 5 side.

  FIG. 6 is a diagram illustrating frequency characteristics of signals output from the wheel sensor when a large vibration is applied to a locally abnormal tire from an uneven road surface. The vertical axis represents the magnitude of the signal amplitude, and the horizontal axis represents the rotational order of the tire. A solid line represents a signal component when the wheel sensor is not provided with damping material, and a broken line represents a signal component when the wheel sensor is provided with damping material. The vehicle speed on rough roads was set to 60 km / h (primary: about 8 Hz), and the natural frequency of the spring was set to 72 Hz. From FIG. 6, by providing the damping material, the signal component around 72 Hz, which is the natural frequency of the spring, is attenuated compared to when the damping material is not provided, and the rotation order components of the third to seventh tires and 11 It can be seen that the amplitude of the ˜15th order rotational order component is increased. That is, it can be seen that the signal component caused by the uneven road surface is attenuated while leaving the signal component caused by the local abnormality of the tire. In this way, when the component for each rotation order of the tire of the signal output from the wheel sensor using the damping material is integrated, and the integrated value exceeds a predetermined threshold, there is a local abnormality in the tire. By configuring the apparatus to make a determination, it is possible to reliably determine a signal output once per tire rotation. In other words, if the wheel sensor does not include a damping material, it may be determined that there is an abnormality even if there is no abnormality in the tire when vibration is applied from an uneven road surface. By providing the vibration material, as described above, the signal component due to the uneven road surface can be attenuated while leaving the signal component due to the local abnormality of the tire. Only a signal that is output once per rotation of the tire due to the abnormality can be determined.

  FIG. 7 is a schematic diagram showing another aspect of the combination of the rotating body and the sensor. Instead of the gear pulser 1, the rotating body is configured using an alternating magnetizing ring 11, and instead of the wheel sensor 2 as a sensor. This is an example in which a sensor is configured using the magnetic sensor 12. The alternating magnetizing ring 11 is a permanent magnet in which N poles and S poles are alternately arranged in the circumferential direction at a predetermined pitch, and is attached around a hub center shaft portion 8A that is a rotating portion of an axle. On the other hand, the magnetic sensor 12 is arranged on the inner peripheral surface of the axle pipe 9 which is a non-rotating portion of the axle so as to face the outer peripheral surface of the alternating magnetizing ring 11 and continuously changes the magnetic force changed by the rotating alternating magnetizing ring 11. For example, it can be constituted by a Hall element sensor, MR sensor, MI sensor, or the like.

  The magnetic field change detected by the magnetic sensor 12 can be expressed as a change similar to that shown in FIGS.

  Next, the signal processing means 3 for extracting the vibration component caused by the local abnormality of the tire from the output signal of the wheel sensor 2 will be described. FIG. 8 is a block diagram showing the configuration of the signal processing means 3. The signal processing means 3 is a sensor output capturing means 15 that captures the output signal of the wheel sensor 2, and the wheel rotation based on the output signal of the wheel sensor 2. The rotation correlation signal extracting means 16 for extracting the rotation correlation signal correlated with the vehicle, the presence / absence of a tire local abnormality is determined from the rotation correlation signal, and if the determination result is that there is a tire local abnormality, the fact is output to the display alarm device 4. The abnormality determining means 18 is included.

  Here, the rotation correlation signal extraction means 16 may use an adaptive digital filter as shown below. For example, refer to FIG. 9 showing the processing of the rotation correlation signal extraction means 16 in a block diagram. I will explain. The rotation correlation signal extraction means 16 inputs the digital signal X (i) acquired by the sensor output acquisition means 15 and supplies the input signal (reference signal R (i) to the adaptive digital filter 23 via the comparator 24. And the signal obtained by delaying the input signal through the delay circuit 22 (directly supplied to the adaptive digital filter 23) are calculated in the adaptive digital filter 23 in real time, and output as the output signal Y (i). A signal correlated in period is output. Therefore, the output signal Y (i) can be obtained as a signal (periodic signal) correlated with the rotation of the wheel. The obtained output signal Y (i) is input to the tire local abnormality signal extraction means 17.

  The delay time in the delay circuit 22 is preferably equal to or less than the time interval of one rotation of the wheel, but even if it is a time interval of two or more rotations, or a time interval that is slightly different from the time of one rotation, Due to the characteristics of the adaptive digital filter 23, there is no problem in obtaining a periodic component synchronized with the rotation by calculation. Further, even when the time interval of one rotation of the wheel changes depending on the number of rotations (running speed), it can be dealt with by appropriately setting the sampling frequency and tap length of the adaptive digital filter 23. It can also be realized by previously setting three stages of delay time, low speed, medium speed, and high speed, and changing the delay time of the delay circuit 22 in three stages according to the speed. Of course, it is also conceivable to always measure the speed of the vehicle and change the delay time of the delay circuit 22 in real time according to the speed.

  As the adaptive digital filter 23, a conventionally known configuration can be used. In the example shown in FIG. 9, the reference signal R (i) composed of the digital data X (i) measured by the sensor output capturing means 15 and the output Y (i) of the adaptive digital filter are output by the comparator 24. The difference between the two is calculated to obtain the error signal E (i). Therefore, the error signal E (i) can be obtained as a signal (random signal) that is irrelevant to the rotation of the wheel, for example, that contributes to the road surface or the vehicle body. The obtained error signal E (i) is fed back to the coefficient changing unit of the adaptive digital filter 23, and the coefficient of the adaptive digital filter 23 is dynamically changed in accordance with the error signal E (i). 23 optimization is planned. As a method for optimizing the error signal E (i) by feeding it back to the coefficient changing unit of the adaptive digital filter 23, the LMS (least mean square) method, Newton method, A plunging method can be used.

  As an example of the rotational correlation signal extraction means 16, as shown in FIG. 9, a delay circuit 22 is provided between the input portion of the digital signal X (i) from the sensor output acquisition means 15 and the adaptive digital filter 23. In addition to the example, as shown in FIG. 10, a delay circuit 22 is provided between the input portion of the digital signal X (i) from the sensor output capturing means 15 and the comparator 24, and the reference signal R (i) is provided. Even if it is delayed, the same effects as those shown in FIG. 9 can be obtained.

  In order to determine the presence or absence of a tire local abnormality from the rotation correlation signal, for example, it can be performed as follows. When the coil spring 5 serving as an urging means is vibrated from the outside, its natural frequency component is amplified and vibrates, and the rotation correlation signal when there is no occurrence of local abnormality in the tire and Since the amplitude at the frequency is different, the amplitude at the natural frequency of each wheel in the state where there is no local abnormality is stored for each wheel, and the amplitude at the normal time is larger than a predetermined threshold. It may be determined that an abnormality has occurred when a change appears. Further, instead of comparing the own wheel with no abnormality occurrence, it is also possible to compare with the amplitude of the natural frequency of the adjacent wheels on the left and right, and in this case also, the natural frequency of the adjacent wheels. An abnormality can be determined by determining that an abnormality is detected when a difference in amplitude at or above that is greater than or equal to a predetermined threshold is detected.

1 is a layout diagram illustrating a configuration of a tire abnormality detection device according to an embodiment of the present invention. It is sectional drawing which shows the attachment aspect of a gear pulser and a wheel sensor. It is a schematic diagram which shows the detection principle of the wheel sensor 2. FIG. It is a graph which shows the time change of a magnetic field. It is a schematic diagram which shows the example which provided the damping material in the wheel sensor. It is a figure which shows the frequency characteristic of the signal output from a wheel sensor when providing a damping material in a wheel sensor. It is a schematic diagram which shows the other aspect of the combination of a rotary body and a sensor. It is a block diagram which shows the structure of a signal processing means. It is a block diagram which shows the process of a rotation correlation signal extraction means. It is a block diagram which shows the other aspect of a rotation correlation signal extraction means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gear pulsar 1a Gear pulsar tooth 2 Wheel sensor 3 Signal processing means 4 Display alarm device 5 Coil spring 6 Linear motion guide 7 Permanent magnet 8 Hub 8A Hub central shaft portion 9 Axle pipe 10 Tire abnormality detection device 11 Alternating magnetization ring 12 Magnetic sensor 14 Magnetic field Detection coil 14a Core 15 Sensor output taking means 16 Rotation correlation signal taking means 18 Abnormality judging means 22 Delay circuit 23 Adaptive digital filter 24 Comparator 25 Damping material 26 Weight T Tire

Claims (7)

A rotating body that is attached to a wheel and rotates around its central axis and periodically changes a physical quantity at a predetermined position by the rotation, and is attached to an axle that supports the wheel, and continuously detects the physical quantity. A sensor for outputting a signal corresponding to the physical quantity, and a signal processing means for extracting a vibration component caused by a local abnormality of the tire superimposed on a periodic component due to rotation of the rotating body from the output signal of the sensor; In the tire abnormality detection device comprising
A tire abnormality detection device in which the sensor is attached to the non-rotating portion of the axle via an urging means.   The rotating body is composed of a gear pulser made of a magnetic material having high permeability, and the sensor is composed of a permanent magnet and a coil that generates an electromotive force by a magnetic field from the permanent magnet that changes as the gear pulser rotates. The tire abnormality detection device according to claim 1. The rotating body is composed of permanent magnets in which N poles and S poles are alternately arranged in a circumferential direction at a predetermined pitch,
The tire abnormality detection device according to claim 1, wherein the sensor is configured by a magnetic sensor that detects a magnetic field that changes with rotation of the permanent magnet.   Means for extracting only a rotational correlation signal correlated with wheel rotation from the output signal of the sensor using an adaptive digital filter, and an abnormality determining means for determining a local abnormality of the tire from the rotational correlation signal; The tire abnormality detection device according to claim 1, comprising:   The tire abnormality detection device according to any one of claims 1 to 4, wherein the natural frequency of the urging means is made to coincide with the natural frequency of the tire.   The tire abnormality detection device according to any one of claims 1 to 4, wherein the natural frequency of the biasing means is made to coincide with the secondary natural frequency of the tire. The tire abnormality detection device according to any one of claims 1 to 4, wherein the sensor is provided with a damping material that attenuates a signal amplitude at a natural frequency of the biasing means.

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