JP4272113B2 - Tire pressure checking system, tire pressure checking device, and tire pressure checking method - Google Patents

Description

  The present invention relates to a tire air pressure inspection system, a tire air pressure inspection device, and a tire air pressure inspection method for inspecting the internal pressure of a pneumatic tire assembled on a rim wheel.

  Conventionally, as a method for checking whether or not the air pressure (internal pressure) filled in a pneumatic tire for automobiles is normal, a method of directly measuring the internal pressure with an air pressure measuring device (tire pressure gauge) has been widely used.

  Furthermore, in recent years, a sensor for measuring internal pressure provided in an air valve provided in a rim wheel or rim hole in which a pneumatic tire is assembled, and internal pressure data measured by the sensor or an internal pressure drop alarm based on the internal pressure data are provided. A tire pressure monitoring system (Tire Pressure Monitoring System, hereinafter referred to as direct type TPMS) composed of a transmitter that transmits to a vehicle side using wireless communication has been put into practical use.

In addition, the internal pressure is not measured directly, but the resonance frequency (tire cavity resonance frequency) of the pneumatic tire is extracted from the signal including the vibration frequency component of the pneumatic tire by wavelet transform, and the internal pressure is determined based on the resonance frequency. TPMS (hereinafter referred to as indirect TPMS) is also known (for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-241969 (page 3-5, FIG. 1-2)

  However, the above-described conventional technique has the following problems. First, the direct type TPMS is very expensive, and is currently mounted only on some high-priced vehicles on which run-flat tires are mounted.

  Further, in the method of estimating the internal pressure based on the “resonance frequency” (tire cavity resonance frequency) of the pneumatic tire, the amount of the frequency that changes as the internal pressure decreases is very small. The resonance frequency may change depending on the shape or the like. For this reason, for example, when a pneumatic tire is replaced, a difference occurs between the resonance frequency before the replacement and the resonance frequency after the replacement, and the estimation accuracy of the internal pressure is lowered.

  Therefore, in the indirect TPMS disclosed in Patent Document 1 described above, wavelet transform is executed for three or more frequencies, and the wavelet coefficient obtained by the wavelet transform is determined for a predetermined time using the least square method. A complicated process is performed in which an approximate curve of each average value is obtained and the internal pressure is estimated based on a constant of the approximate curve.

  In addition, the method of measuring the internal pressure with an air pressure measuring instrument that has been widely used in the past requires that the air pressure measuring instrument be pressed against the air valve (valve stem), and when the valve cap attached to the air valve is removed or replaced. In addition, there was a problem that the hands of the measurer became dirty. Furthermore, when the method of pressing the air pressure measuring device on the air valve is not appropriate, there is a problem that air filled in the pneumatic tire leaks.

  That is, there has been a demand for a method that can easily check the internal pressure of a pneumatic tire that needs to be performed on a daily basis, such as before traveling, and by using a device that is less expensive than TPMS.

  Therefore, the present invention has been made in view of such a situation, and compared with a conventional tire pressure monitoring system (TPMS) or an air pressure measuring device (tire pressure gauge), a method for checking the internal pressure of a pneumatic tire, It is an object of the present invention to provide a tire air pressure inspection system, a tire air pressure inspection device, and a tire air pressure inspection method that are more cost effective.

In order to solve the problems described above, the present invention has the following features. First, a first feature of the present invention is that a vibration unit (for example, a hammer 120) that applies predetermined vibration to a pneumatic tire (pneumatic tire 10) assembled to a rim wheel (rim wheel 11), and the vibration described above. A vibration sound data collection unit (microphone 110 and vibration sound data collection unit 201) that collects vibration sound data that is vibration sound data of the pneumatic tire generated by the above, and is included in the vibration sound data and from other frequencies The tire cavity resonance frequency at a first time (amplitude value a ₁ ) of the tire cavity resonance frequency, which is a peak frequency with a large amplitude value, and the tire cavity resonance at a second time when a predetermined time has elapsed from the first time An attenuation rate calculation unit (attenuation rate calculation unit 202) that calculates an actual attenuation rate that is an attenuation rate based on the amplitude value of the frequency (amplitude value a ₂ ); By determining whether or not the difference between the basic attenuation rate, which is the attenuation rate when the internal pressure of the ear is normal, and the measured attenuation rate calculated by the attenuation rate calculation unit is within a predetermined threshold, An estimation unit (estimation unit 204) that estimates whether or not the internal pressure of the pneumatic tire is normal, and a notification unit (display) that notifies whether or not the internal pressure is normal based on the estimation result estimated by the estimation unit And a tire pressure inspection system including the unit 206).

  According to this feature, it is estimated whether the internal pressure of the pneumatic tire is normal based on the attenuation rate of the amplitude value (strength) of the tire cavity resonance frequency. Here, the amount of the tire cavity resonance frequency that changes as the internal pressure decreases is very small. To estimate the internal pressure based on the tire cavity resonance frequency, as shown in Patent Document 1 described above, a complicated process is required. Need to do.

  Therefore, the inventors use the attenuation rate of the amplitude value (intensity) of the tire cavity resonance frequency instead of the change of the tire cavity resonance frequency in order to estimate the internal pressure of the pneumatic tire with high accuracy and simple processing. We focused on.

  In other words, according to such a feature, it is possible to avoid the use of expensive devices and the execution of complicated processing as compared with the conventional direct type and indirect type TPMS, and a simpler system configuration can be achieved.

  Furthermore, according to such a feature, since the microphone that can be brought into contact with any part of the pneumatic tire is used for collecting the vibration sound, the measurer does not need to touch the air valve when checking the internal pressure.

  That is, the measurer does not need to remove or reattach the valve cap attached to the air valve as in the conventional method of measuring the internal pressure with an air pressure measuring instrument (tire pressure gauge), and the measurer's hand becomes dirty. You can avoid that.

  Moreover, since it is not necessary to use an air pressure measuring device, it is possible to prevent the air filled in the pneumatic tire from leaking because the method of pressing the air pressure measuring device to the air valve is not appropriate.

  In other words, according to such a feature, the tire pressure check is more cost-effective than the conventional method for checking the internal pressure of a pneumatic tire using a tire pressure monitoring system (TPMS) or a pressure measuring device (tire pressure gauge). A system can be provided.

  A second feature of the present invention relates to the first feature of the present invention, wherein the attenuation factor calculation unit continuously calculates the amplitude value of the tire cavity resonance frequency using wavelet transform or short-time Fourier transform. The gist is to do.

  A third feature of the present invention relates to the first feature or the second feature of the present invention, wherein the attenuation factor calculation unit is collected by the vibration sound data collecting unit when the internal pressure of the pneumatic tire is normal. The basic attenuation rate is further calculated using the vibration sound data, and the estimation unit has a difference between the basic attenuation rate calculated by the attenuation rate calculation unit and the actually measured attenuation rate within a predetermined threshold. The gist is to estimate whether or not the internal pressure of the pneumatic tire is normal.

  According to this feature, since the basic damping rate is calculated based on the vibration sound collected when the pneumatic tire is normal, the basic damping rate data can be appropriately generated and updated (calibrated).

  A fourth feature of the present invention is according to the first to third features of the present invention, wherein the attenuation factor calculation unit further calculates an actually measured attenuation factor of a multiple frequency that is an integer multiple of the tire cavity resonance frequency. The estimation unit determines that a difference between a basic attenuation rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured attenuation rate of the multiple frequency calculated by the attenuation rate calculation unit is a predetermined value. The gist is to estimate whether or not the internal pressure of the pneumatic tire is normal by further determining whether or not it is within a threshold value.

  According to this feature, in addition to the tire cavity resonance frequency, an attenuation factor (basic attenuation factor, actually measured attenuation factor) of an amplitude value of a multiple frequency that is an integer multiple (for example, two times) the tire cavity resonance frequency is used. Therefore, it is possible to estimate whether the internal pressure of the pneumatic tire is normal with higher accuracy.

  A fifth feature of the present invention relates to the first to fourth features of the present invention, and is a data storage unit (data for storing internal pressure estimated attenuation rate data, which is a plurality of attenuation rate data having different internal pressure values. A storage unit 203), and the estimation unit estimates the value of the internal pressure by comparing the internal pressure estimated attenuation rate data stored in the data storage unit with the measured attenuation rate. And

  According to this feature, a plurality of estimated internal pressure attenuation rate data with different internal pressure values, for example, the attenuation rate data of each internal pressure value for every 10 kPa from 200 kPa to 100 kPa, and the actually measured attenuation rate are compared. Not only whether the internal pressure of the tire is normal, but also the value of the internal pressure can be estimated.

  A sixth feature of the present invention relates to the first to fifth features of the present invention, in which the vibration unit (vibration device 140) is a tread (tread 10tr) or sidewall (sidewall) of the pneumatic tire. The gist is to have a hammer (hammer 141) that strikes 10 sw) and a power source (spring 141s) that moves the hammer at a predetermined speed.

  According to such a feature, since the hammer hits the tread or sidewall of the pneumatic tire at a predetermined speed, a predetermined vibration is always applied as compared with the case where the measurer hits the pneumatic tire using the hammer. Can be added to. For this reason, the internal pressure of the pneumatic tire can be estimated with higher accuracy.

  According to a seventh feature of the present invention, the vibration unit (vibration device 150) has a protrusion (protrusion part 151) that is installed on the road surface and contacts the tread of the pneumatic tire that rolls at a predetermined speed. This is the gist.

  According to this feature, since the excitation unit has a protrusion that comes into contact with the tread of the pneumatic tire, a vehicle equipped with the pneumatic tire gets over the protrusion at a constant speed, so that a predetermined vibration is always generated in the air. Can be added to the tires.

  According to an eighth aspect of the present invention, there is provided a vibration sound data collecting unit for collecting vibration sound data which is vibration sound data of the pneumatic tire generated by a predetermined vibration applied to the pneumatic tire assembled to the rim wheel. And the amplitude value at the first time of the tire cavity resonance frequency which is included in the vibration sound data and has a larger amplitude value than the other frequencies, and the first time after a predetermined time has elapsed from the first time. An attenuation rate calculation unit that calculates an actual attenuation rate that is an attenuation rate based on an amplitude value of the tire cavity resonance frequency at time 2, and a basic attenuation rate that is the attenuation rate when the internal pressure of the pneumatic tire is normal; The internal pressure of the pneumatic tire is normal by determining whether or not the difference from the measured attenuation rate calculated by the attenuation rate calculation unit is within a predetermined threshold value. An estimation unit for estimating a whether, on the basis of the estimation result estimated by the estimator, the internal pressure is summarized in that a tire pressure checking device and a notification unit for notifying whether normal or not.

  A ninth feature of the present invention is according to the eighth feature of the present invention, wherein the attenuation factor calculation unit continuously calculates the amplitude value of the tire cavity resonance frequency using wavelet transform or short-time Fourier transform. The gist is to do.

  A tenth feature of the present invention relates to the eighth feature or the ninth feature of the present invention, wherein the damping factor calculation unit is collected by the vibration sound data collecting unit when the internal pressure of the pneumatic tire is normal. The basic attenuation rate is further calculated using the vibration sound data, and the estimation unit has a difference between the basic attenuation rate calculated by the attenuation rate calculation unit and the actually measured attenuation rate within a predetermined threshold. The gist is to estimate whether or not the internal pressure of the pneumatic tire is normal.

  An eleventh feature of the present invention relates to the eighth to tenth features of the present invention, wherein the attenuation factor calculation unit further calculates an actually measured attenuation factor of a multiple frequency that is an integer multiple of the tire cavity resonance frequency. The estimation unit determines that a difference between a basic attenuation rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured attenuation rate of the multiple frequency calculated by the attenuation rate calculation unit is a predetermined value. The gist is to estimate whether or not the internal pressure of the pneumatic tire is normal by further determining whether or not it is within a threshold value.

  A twelfth feature of the present invention relates to the eighth to eleventh features of the present invention, and further includes a data storage unit for storing estimated internal pressure attenuation rate data, which is a plurality of attenuation rate data having different internal pressure values. The estimation unit estimates the value of the internal pressure by comparing the internal pressure estimated attenuation rate data stored in the data storage unit with the measured attenuation rate.

  A thirteenth feature of the present invention relates to the eighth to twelfth features of the present invention, and is a hammer (hammer 161) for striking the tread or sidewall of the pneumatic tire and power for moving the hammer at a predetermined speed. The gist is to further include a source (rotating shaft portion 161s).

  A fourteenth feature of the present invention is a step of applying a predetermined vibration to a pneumatic tire assembled to a rim wheel, and a step of collecting vibration sound data which is vibration sound data of the pneumatic tire generated by the vibration. And the amplitude value at the first time of the tire cavity resonance frequency which is included in the vibration sound data and has a larger amplitude value than the other frequencies, and the first time after a predetermined time has elapsed from the first time. A step of calculating an actual attenuation rate that is an attenuation rate based on an amplitude value of the tire cavity resonance frequency at time 2, a basic attenuation rate that is the attenuation rate when the internal pressure of the pneumatic tire is normal, and the calculation Determining whether or not the difference from the measured attenuation rate calculated in the step is within a predetermined threshold value. A tire pressure check method comprising: a step of estimating whether the pressure is normal; and a step of notifying whether the internal pressure is normal based on the estimation result estimated in the step of estimating. To do.

  A fifteenth feature of the present invention relates to the fourteenth feature of the present invention, wherein, in the step of calculating, the amplitude value of the tire cavity resonance frequency is continuously calculated using wavelet transform or short-time Fourier transform. This is the gist.

  A sixteenth feature of the present invention relates to the fourteenth or fifteenth feature of the present invention, wherein, in the calculating step, the vibration sound collected in the collecting step when the internal pressure of the pneumatic tire is normal. The basic attenuation rate is further calculated using data, and in the estimating step, whether or not a difference between the basic attenuation rate calculated in the calculating step and the actually measured attenuation rate is within a predetermined threshold value. The gist is that it is estimated whether or not the internal pressure of the pneumatic tire is normal.

  A seventeenth feature of the present invention relates to the fourteenth to sixteenth features of the present invention, and in the step of calculating, an actually measured attenuation rate of a multiple frequency that is an integer multiple of the tire cavity resonance frequency is further calculated. In the estimating step, a difference between a basic attenuation rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured attenuation rate of the multiple frequency calculated in the calculating step is a predetermined threshold value. The gist is that it is estimated whether or not the internal pressure of the pneumatic tire is normal by further determining whether or not it is within the range.

  An eighteenth feature of the present invention relates to the fourteenth to seventeenth features of the present invention, and in the step of estimating, an internal pressure estimated attenuation rate data, which is a plurality of attenuation rate data having different internal pressure values, and the The gist is that the value of the internal pressure is estimated by comparing the measured attenuation rate.

  According to the present invention, compared with a conventional method for checking the internal pressure of a pneumatic tire using a tire pressure monitoring system (TPMS) or an air pressure measuring device (tire pressure gauge), a tire pressure checking system having a more cost-effectiveness, A tire pressure checking device and a tire pressure checking method can be provided.

(Configuration of tire pressure inspection system)
Next, an example of an embodiment of a tire pressure inspection system according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Schematic Configuration of Tire Pressure Inspection System FIG. 1 shows a schematic configuration of a tire pressure inspection system according to the present embodiment. As shown in the figure, the tire pressure inspection system according to this embodiment includes a microphone 110, a hammer 120, and a tire pressure inspection device 200.

  The microphone 110 is attached to the sidewall 10sw or tread 10tr of the pneumatic tire 10 assembled to the rim wheel 11, and the vibration sound of the pneumatic tire 10 generated by the vibration applied to the pneumatic tire 10 using the hammer 120. Is to collect.

  The microphone 110 has a sticky plane, and can be easily attached to and detached from the pneumatic tire 10 (tread 10tr or sidewall 10sw). The microphone 110 is a so-called contact type microphone that collects vibration sounds of the pneumatic tire 10 and is similar to the microphone that collects sound generated by an instrument such as a guitar.

  In the present embodiment, the pneumatic tire 10 is attached to the vehicle 1. The pneumatic tire 10 according to the present embodiment is a run flat tire, and the size thereof is 225 / 60R17. In the present embodiment, the pneumatic tire 10 is mounted on the vehicle 1, but the tire pressure check system is also applied to a pneumatic tire that is not mounted on the vehicle (for example, a pneumatic tire that is laid flat). Of course, it can be applied.

  The hammer 120 applies predetermined vibration to the pneumatic tire 10 assembled to the rim wheel 11, and constitutes a vibration unit in the present embodiment. In addition, the hammer 120 according to the present embodiment is made of metal, and is used by a measurer of the internal pressure of the pneumatic tire 10 (for example, a driver or a mechanic of the vehicle 1) in order to apply predetermined vibration to the pneumatic tire 10. . Specifically, the hammer 120 is used for the measurer to hit the sidewall 10sw or the tread 10tr.

  In this embodiment, the hammer 120 is made of metal, but may be made of plastic or wood as long as a predetermined vibration can be applied to the pneumatic tire 10.

  The tire pressure checking device 200 is connected to the microphone 110 and estimates the internal pressure of the pneumatic tire 10 based on vibration sound data that is vibration sound data collected by the microphone 110.

  The tire pressure inspection device 200 includes a data selection unit 205 for selecting the type and size of the pneumatic tire 10 and a display unit 206 for displaying an estimation result of the internal pressure of the pneumatic tire 10 on the surface of the housing. ing.

  In the present embodiment, the display unit 206 is provided on the surface of the housing of the tire pressure checking device 200, but the display unit 206 may be separated from the tire pressure checking device 200.

(2) Logic Block Configuration of Tire Pressure Checking Device Next, the logic block configuration of the tire pressure checking device 200 described above will be described with reference to FIG.

  As shown in the figure, the tire pressure checking device 200 includes a vibration sound data collection unit 201, an attenuation rate calculation unit 202, a data storage unit 203, an estimation unit 204, a data selection unit 205, and a display unit 206. have.

  The vibration sound data collection unit 201 collects vibration sound data which is vibration sound data of the pneumatic tire 10 generated by vibration applied using the hammer 120. In the present embodiment, the vibration sound data collection unit 201 vibrates together with the microphone 110. The sound data collection unit is configured.

  Specifically, the vibration sound data collection unit 201 receives an electric signal of vibration sound transmitted from the microphone 110, sequentially digitizes the received electric signal, and outputs the digitized signal to the attenuation factor calculation unit 202.

  If the vibration sound data collection unit 201 cannot normally collect the vibration sound data, for example, the vibration sound data collection unit 201 may generate the vibration sound within a predetermined time (for example, 15 seconds) after the tire air pressure inspection device 200 is turned on. When the data cannot be collected, it can be displayed on the display unit 206 that the vibration sound data cannot be collected normally.

  The attenuation factor calculation unit 202 includes the amplitude value at the first time of the tire cavity resonance frequency that is included in the vibration sound data collected by the vibration sound data collection unit 201 and has a peak frequency larger than the other frequencies. The measured attenuation rate, which is an attenuation rate based on the amplitude value of the tire cavity resonance frequency at the second time when a predetermined time has elapsed from the first time, is calculated.

  Specifically, the attenuation rate calculation unit 202 continuously calculates the amplitude value of the tire cavity resonance frequency using wavelet transform. More specifically, the attenuation rate calculation unit 202 calculates the amplitude value of the tire cavity resonance frequency using a complex Gabor wavelet.

  Here, before describing a more specific function of the attenuation factor calculation unit 202, the tire cavity resonance frequency will be briefly described. For example, as described in “Improvement of tire cavity noise during driving” (Pre-printed tire / road noise 2000 No. 111-00 published in October 2000), the pneumatic tire 10 is applied to the road surface. When contacting the ground, the cross-sectional area in the tread width direction changes along the tire circumferential direction. In this case, two peak frequencies (f_low, f_high) appear as tire cavity resonance frequencies.

  On the other hand, when the pneumatic tire 10 is not in contact with the road surface, the tire cavity resonance frequency is a single peak frequency (f), and the tire cavity resonance frequency (f) can be calculated by (Equation 1). it can.

f = sonic velocity / 2πr (Expression 1)
Note that “r” is a distance (unit: m) from the rotation center of the rim wheel 11 to the center of gravity of the cross section in the tread width direction of the pneumatic tire 10 as described in the document.

  The attenuation factor calculation unit 202 calculates any amplitude value of the above-described tire cavity resonance frequency (f, f_low, or f_high) using a complex Gabor wavelet. Specifically, the attenuation factor calculation unit 202 uses a sine wave of the tire cavity resonance frequency as a mother wavelet, and extracts only the amplitude waveform of the tire cavity resonance frequency.

  The attenuation factor calculation unit 202 determines the tire cavity resonance frequency to be calculated based on the tire cavity resonance frequency data for each type and size of the pneumatic tire stored in the data storage unit 203. To do. Further, the attenuation factor calculation unit 202 can also determine the tire cavity resonance frequency by extracting the peak frequency from the vibration sound data collected by the vibration sound data collection unit 201.

  Further, the attenuation factor calculation unit 202 calculates the tire cavity resonance frequency after a predetermined time (for example, 0.2 seconds) has elapsed since the vibration was applied to the pneumatic tire 10 using the hammer 120 (first time). In addition to calculating the amplitude value, the tire cavity resonance frequency after a predetermined time (for example, 0.7 seconds) has elapsed (second time) from the first time is calculated.

  Further, the attenuation rate calculation unit 202 calculates the attenuation rate (measured attenuation rate) of the amplitude value at the tire cavity resonance frequency from the amplitude value at the first time and the amplitude value at the second time.

  Here, the reason why the attenuation rate calculation unit 202 calculates the amplitude value of the tire cavity resonance frequency after a predetermined time has elapsed after the vibration is applied to the pneumatic tire 10 using the hammer 120 is that This is because a certain time (for example, 0.2 seconds) from when the vibration is applied to the entering tire 10 is excluded from the calculation target because the sound other than the tire cavity resonance frequency is mixed. . In addition, since sounds other than the tire cavity resonance frequency are rapidly attenuated, there is no problem when the attenuation rate calculation unit 202 calculates the attenuation rate.

Further, since the amplitude value of the tire cavity resonance frequency decreases almost exponentially from the _first time (t ₁ ) described above, the amplitude value a ₁ of the tire cavity resonance frequency at the first time and the second value The amplitude value a ₂ of the tire cavity resonance frequency at time (t ₂ ) can be considered to have a relationship as shown in (Expression 2).

a ₂ = a ₁ × exp (p × (t ₂ −t ₁ )) (Formula 2)
Specifically, the attenuation factor calculating section 202 is not limited to the amplitude values a ₁ and an amplitude value a _2, until the amplitude value is sufficiently attenuated continuously measures the amplitude value of the tire cavity resonance frequency, Attenuation rate (unit: / second) is calculated by fitting the measured result to a (t) = a ₀ × exp (−pt)) using the least square method. That is, the “amplitude value” of the tire cavity resonance frequency is the amplitude value of the tire cavity resonance frequency at a certain moment.

In addition, the attenuation rate calculation unit 202 (or estimation unit 204 described later) determines that the vibration sound data cannot be normally collected when the error between the calculated attenuation rate (actually measured attenuation rate) and the basic attenuation rate is large. Also good.

  The attenuation rate calculation unit 202 calculates the attenuation rate (p) using (Equation 2), and outputs the calculated attenuation rate (actual attenuation rate) to the estimation unit 204.

  Further, in order to estimate the internal pressure of the pneumatic tire 10 with higher accuracy, the attenuation rate calculation unit 202 has an attenuation rate (actual attenuation rate) of a multiple frequency that is an integer multiple of the tire cavity resonance frequency (f, f_low, or f_high). ) Can be further calculated.

  In the present embodiment, 220 Hz (f_low) is determined as the tire cavity resonance frequency of the pneumatic tire 10, and a frequency (440 Hz) twice the tire cavity resonance frequency is used as the multiple frequency.

  The multiple frequency is not limited to twice the tire cavity resonance frequency, and may be a different multiple frequency as long as it is an integer (n) times. In addition, the attenuation factor calculation unit 202 estimates the internal pressure of the pneumatic tire 10 with higher accuracy, so the multiple frequency is not limited to one frequency, and a plurality of multiple frequencies may be used simultaneously.

  Further, the damping rate calculation unit 202 uses the vibration sound data collected by the vibration sound data collection unit 201 when the internal pressure of the pneumatic tire 10 is normal, that is, when the internal pressure of the pneumatic tire 10 is normal, that is, It is also possible to further calculate a basic damping rate that is a damping rate of the tire cavity resonance frequency (and multiple frequency, hereinafter the same) when a specified internal pressure (for example, 200 kPa) is filled in the pneumatic tire 10.

  The data storage unit 203 stores internal pressure estimated attenuation rate data, which is data of a plurality of attenuation rates with different internal pressure values of the pneumatic tire 10, and tire cavity resonance frequency data.

  Specifically, the data storage unit 203 includes, for example, an attenuation rate (basic attenuation rate) of the tire cavity resonance frequency when a specified internal pressure (for example, 200 kPa) is filled, for example, every 10 kPa up to 100 kPa (190 kPa, 180 kPa...) Is stored as internal pressure estimated attenuation rate data.

  The internal pressure value to be prepared as the internal pressure estimated attenuation rate data and the data such as the tire cavity resonance frequency can be changed depending on the type and size of the pneumatic tire to be inspected for internal pressure, and the necessary data is stored in the data storage unit. 203 can be stored.

  The estimation unit 204 determines whether or not the difference between the basic attenuation rate, which is the attenuation rate when the internal pressure of the pneumatic tire 10 is normal, and the actually measured attenuation rate calculated by the attenuation rate calculation unit 202 is within a predetermined threshold. Is used to estimate whether or not the internal pressure of the pneumatic tire 10 is normal.

  Specifically, the estimation unit 204 determines whether or not the difference between the basic attenuation rate and the actually measured attenuation rate calculated by the attenuation rate calculation unit 202 is within a predetermined threshold.

  Further, the estimation unit 204 further determines whether or not the difference between the basic attenuation rate of the multiple frequency and the actual attenuation rate of the multiple frequency calculated by the attenuation rate calculation unit 202 is within a predetermined threshold. It can be estimated whether the internal pressure of the pneumatic tire 10 is normal.

In the present embodiment, as described above, a frequency (440 Hz) that is twice the tire cavity resonance frequency (220 Hz) of the pneumatic tire 10 is used as a multiple frequency, and 10 ^{−1 is set} as a threshold value of an attenuation rate of 220 Hz. ^0.2 / sec or more (p = 2.7 or more) is set, and 10 ^−1.8 / sec or less (p = 4.1 or less) is set as the threshold value of the attenuation rate of 440 Hz.

  Furthermore, the estimation unit 204 can estimate the “value” of the internal pressure of the pneumatic tire 10 by comparing the internal pressure estimated attenuation rate data stored in the data storage unit 203 with the actually measured attenuation rate.

  Specifically, the estimation unit 204 sequentially compares the actually measured attenuation rate (p) calculated by the attenuation rate calculation unit 202 with the attenuation rate (p) of each internal pressure value constituting the internal pressure estimated attenuation rate data. As a result of sequentially comparing the measured attenuation rate (p) with the attenuation rate (p) of each internal pressure value, the estimation unit 204 determines the internal pressure value corresponding to the closest attenuation rate (p) to the measured attenuation rate of the pneumatic tire 10. Considering the internal pressure, the display unit 206 displays the internal pressure value or whether the internal pressure is normal.

  The data selection unit 205 causes the measurer to select the type and size of the pneumatic tire 10, and in the present embodiment, the data selection unit 205 includes a triangular selection key and a circular determination key (see FIG. 1). .

  Information on the type and size of the pneumatic tire selected using the data selection unit 205 is notified to the data storage unit 203 and the estimation unit 204, and the tire cavity resonance frequency and internal pressure estimation corresponding to the type and size of the pneumatic tire are performed. Attenuation rate data is selected.

  The display unit 206 reports whether or not the internal pressure of the pneumatic tire 10 is normal based on the estimation result estimated by the estimation unit 204. In the present embodiment, the display unit 206 forms a notification unit.

  Specifically, the display unit 206 is configured by a liquid crystal display, and based on the estimation result of the internal pressure of the pneumatic tire 10 estimated by the estimation unit 204, whether or not the internal pressure of the pneumatic tire 10 is normal is determined. indicate.

  Further, the display unit 206 includes the internal pressure value of the pneumatic tire 10 estimated by the estimation unit 204, the type and size of the pneumatic tire stored in the data storage unit 203, and internal pressure estimated attenuation rate data for each size, Data on the tire cavity resonance frequency can also be displayed.

(Operation of tire pressure check system)
Next, the operation of the tire pressure inspection system described above will be described.

(1) Acquisition of Basic Damping Rate First, an operation for obtaining the basic damping rate, which is the damping rate of the amplitude value of the tire cavity resonance frequency when the internal pressure of the pneumatic tire 10 is normal, will be described with reference to FIG. .

  In step S <b> 10, the measurer of the internal pressure of the pneumatic tire 10 attaches the microphone 110 to the pneumatic tire 10. The measurer is a driver of the vehicle 1 or a mechanic as described above.

  In step S <b> 20, the measurer hits the sidewall 10 sw or the tread 10 tr of the pneumatic tire 10 using the hammer 120 and applies vibration to the pneumatic tire 10. It is assumed that the pneumatic tire 10 hit in step S20 has a specified internal pressure (200 kPa).

  In step S <b> 30, the tire air pressure inspection device 200 collects vibration sound of the pneumatic tire 10 generated by vibration applied to the pneumatic tire 10 using the hammer 120 as vibration sound data using the microphone 110.

  In step S40, the tire pressure checking apparatus 200 determines whether or not the vibration sound data has been normally collected.

  When vibration sound data cannot be collected normally (NO in step S40), for example, the pneumatic tire 10 cannot be hit sufficiently, and a predetermined time (for example, 15 If the vibration sound data cannot be collected within a second), in step S50, the tire pressure checking device 200 notifies the measurer that the vibration sound data cannot be collected normally. Specifically, tire pressure inspection apparatus 200 displays on the display unit 206 characters “FAIL” indicating that vibration sound data could not be collected normally. In this case, the process from step S20 is repeated.

  On the other hand, if the vibration sound data can be normally collected (YES in step S40), the tire air pressure inspection device 200 determines the tire cavity resonance frequency of the pneumatic tire 10 in step S60.

  Specifically, the tire pressure checking device 200 refers to the data stored in the data storage unit 203 based on the type and size of the pneumatic tire 10 selected in advance by the measurer, and determines the tire cavity resonance frequency. Determine the value.

  Note that the tire pressure inspection device 200 can also determine the tire cavity resonance frequency of the pneumatic tire 10 by extracting the peak frequency from the vibration sound data collected in step S30. In the present embodiment, it is assumed that 220 Hz is determined as the tire cavity resonance frequency of the pneumatic tire 10.

  In step S70, the tire air pressure inspection device 200 calculates the amplitude value of the determined tire cavity resonance frequency (220 Hz) using the complex Gabor wavelet, and calculates the attenuation rate (p) of the amplitude value.

  In addition to the tire cavity resonance frequency (220 Hz), the tire pressure checking device 200 calculates an amplitude value of 440 Hz as a multiple frequency of the tire cavity resonance frequency, and calculates an attenuation rate (p) of the amplitude value.

  Here, FIGS. 6A and 6B show attenuation states of the amplitude values of the tire cavity resonance frequency (220 Hz) and a multiple frequency (440 Hz) of the tire cavity resonance frequency.

  The dotted line in FIG. 5A shows the attenuation state of the amplitude value of the tire cavity resonance frequency (220 Hz) when the internal pressure of the pneumatic tire 10 is normal (200 kPa). Moreover, the dotted line in the figure (b) has shown the attenuation | damping condition of the amplitude value of the multiple frequency (440 Hz) in case the internal pressure of the pneumatic tire 10 is normal (200 kPa).

  As described above, the pneumatic tire 10 according to the present embodiment is a run flat tire, and the size thereof is 225 / 60R / 17.

The basic damping rate (p) is the amplitude value a _{1 at} time t ₁ (first time) when 0.2 seconds have elapsed from time t ₀ when vibration is applied to the pneumatic tire 10 using the hammer 120. , Based on the amplitude value a _{2 at} time t ₂ (second time) when 0.7 seconds have elapsed from time t ₁ .

More specifically, as described above, the basic attenuation rate (p) is calculated using (Equation 2). Thus, by calculating the basic attenuation rate (p) for the period from time t ₁ to time t ₂ , the amplitudes in the regions A ₁ and A ₂ in which sounds other than the tire cavity resonance frequency are also mixed. The value is excluded from the calculation target of the attenuation rate (p). Note that the value of the time t ₁ and time t ₂ can be appropriately changed according to the type and size of the pneumatic tire which is the subject of inspection of the internal pressure.

  Next, as shown in FIG. 3, in step S <b> 80, the tire pressure inspection device 200 stores the calculated basic damping rate data in the data storage unit 203.

(2) Estimation of Internal Pressure of Pneumatic Tire Next, an operation for estimating the internal pressure of the pneumatic tire 10 will be described with reference to FIG.

  In step S <b> 110, the measurer of the internal pressure of the pneumatic tire 10 attaches the microphone 110 to the pneumatic tire 10 in the same manner as the basic damping rate acquisition operation shown in FIG. 3.

  In step S <b> 120, the measurer hits the sidewall 10 sw or the tread 10 tr of the pneumatic tire 10 using the hammer 120 and applies vibration to the pneumatic tire 10.

  In step S <b> 130, the tire air pressure inspection device 200 collects vibration sound of the pneumatic tire 10 as vibration sound data using the microphone 110.

  In step S140, the tire pressure checking device 200 determines whether or not the vibration sound data has been normally collected.

  When the vibration sound data cannot be normally collected (NO in step S140), in step S50, the tire pressure checking device 200 notifies the measurer that the vibration sound data cannot be normally collected. Specifically, as in the case of obtaining the basic damping rate (see FIG. 3), the tire pressure checking device 200 displays “FAIL” on the display unit 206 indicating that the vibration sound data could not be collected normally. indicate. In this case, the process from step S120 is repeated.

  On the other hand, when the vibration sound data can be normally collected (YES in step S140), in step S160, the tire air pressure inspection device 200 calculates the actual attenuation rate of the pneumatic tire 10.

  Specifically, as described above, the tire pressure inspection device 200 continuously calculates the amplitude value of the tire cavity resonance frequency using the complex Gabor wavelet. Next, the tire pressure checking device 200 calculates an attenuation rate (actually measured attenuation rate) using (Equation 2).

More specifically, the tire pressure inspection device 200 continuously measures the amplitude value of the tire cavity resonance frequency until the amplitude value of the tire cavity resonance frequency is sufficiently attenuated, Attenuation rate (p) is calculated by fitting a (t) = a ₁ × exp (−p (t)) using multiplication.

  In step S170, the tire pressure checking device 200 compares the basic attenuation rate of the pneumatic tire 10 with the actually measured attenuation rate calculated in step S160.

In step S180, the tire pressure checking apparatus 200 determines whether or not the difference between the basic attenuation rate and the actually measured attenuation rate is within a threshold range. Specifically, 10 ^−1.2 / second or more (p = 2.7 or more) is used as the threshold value of the attenuation rate of 220 Hz, and 10 ^−1.8 / second or less (as the threshold value of the attenuation rate of 440 Hz) ( p = 4.1 or less) is used.

  When the difference between the basic damping rate and the actually measured damping rate is within the threshold range (YES in step S180), in step S190, the tire pressure checking device 200 estimates that the internal pressure of the pneumatic tire 10 is normal.

  In step S <b> 200, the tire pressure checking device 200 notifies that the internal pressure of the pneumatic tire 10 is normal. Specifically, the tire pressure checking device 200 displays “OK” on the display unit 206 indicating that the internal pressure of the pneumatic tire 10 is normal.

  On the other hand, when the difference between the basic damping rate and the actually measured damping rate is outside the range of the threshold value (NO in step S180), in step S210, the tire pressure checking device 200 indicates that the internal pressure of the pneumatic tire 10 has decreased. presume.

  The tire air pressure inspection device 200 provides a threshold value of an error between the basic damping rate and the actually measured damping rate. When the measured damping rate exceeds the threshold value of the error, the tire pressure checking device 200 measures again without determining that the internal pressure has decreased. You may request that

  In step S220, the tire air pressure inspection device 200 notifies that the internal pressure of the pneumatic tire 10 has decreased. Specifically, the tire air pressure inspection device 200 displays “NG” on the display unit 206 indicating that the internal pressure of the pneumatic tire 10 is abnormal.

  Here, the solid lines in the graphs shown in FIGS. 6A and 6B indicate the measured attenuation rates of the tire cavity resonance frequency (220 Hz) and the multiple frequency (440 Hz) when the internal pressure of the pneumatic tire 10 is reduced to 100 kPa. Each is shown.

  When the internal pressure of the pneumatic tire 10 is reduced to 100 kPa, the attenuation rate of the tire cavity resonance frequency (220 Hz) is larger than the attenuation rate (basic attenuation rate) at the specified internal pressure (200 kPa). On the other hand, the attenuation rate (actual attenuation rate) of the multiple frequency (440 Hz) is smaller than the attenuation rate at the specified internal pressure (200 kPa).

  Thus, at the tire cavity resonance frequency (220 Hz) and the multiple frequency (440 Hz), the attenuation characteristic of the amplitude value differs depending on the internal pressure value, so by comparing the basic attenuation rate and the actual attenuation rate of both frequencies, Whether the internal pressure of the pneumatic tire 10 is normal can be estimated with higher accuracy.

  Further, in the operation flow shown in FIG. 4 described above, it is estimated only whether the internal pressure of the pneumatic tire 10 is normal or not. However, the tire pressure checking device 200 determines the “value” of the internal pressure of the pneumatic tire 10. It can also be estimated.

  FIG. 5 shows an operation flow for estimating the “value” of the internal pressure of the pneumatic tire 10. FIG. 5 shows an operation flow executed subsequent to the processing of steps S110 to S160 shown in FIG. In addition, when estimating the value of an internal pressure, the process of step S170-S220 shown in FIG. 4 is not performed.

  As shown in FIG. 5, in step S <b> 170 ′, the tire air pressure inspection device 200 sequentially compares the actually measured attenuation rate calculated in step S <b> 160 with the internal pressure estimated attenuation rate data of the pneumatic tire 10.

  Specifically, the tire air pressure inspection device 200 sequentially compares the calculated actually measured attenuation rate and the attenuation rate of each internal pressure value constituting the internal pressure estimated attenuation rate data. More specifically, the tire air pressure inspection device 200 first compares the calculated actual attenuation rate with the attenuation rate of the specified internal pressure (200 kPa), and then sequentially compares them with the attenuation rates of 190 kPa and 180 kPa.

  In step S <b> 180 ′, the tire pressure checking device 200 regards the internal pressure value corresponding to the attenuation rate closest to the actually measured attenuation rate as the internal pressure of the pneumatic tire 10.

  In step S190 ', the tire pressure checking apparatus 200 notifies the internal pressure value of the pneumatic tire 10 considered in step S180'. Specifically, the tire pressure inspection device 200 displays the internal pressure value of the pneumatic tire 10 on the display unit 206.

(Action / Effect)
According to the tire pressure inspection system according to the present embodiment described above, based on the attenuation rate of the amplitude value of the tire cavity resonance frequency included in the vibration sound generated by the vibration applied to the pneumatic tire 10 using the hammer 120. Since the internal pressure is estimated, it is possible to avoid the use of expensive devices and the execution of complicated processing as compared with the conventional direct type and indirect type TPMS, and the system configuration can be simplified.

  Furthermore, according to the present embodiment, the microphone 110 that can be brought into contact with an arbitrary portion of the pneumatic tire 10 is used for collecting the vibration sound. Therefore, the measurer needs to touch the air valve when checking the internal pressure. Absent.

  That is, the measurer does not need to remove or reattach the valve cap attached to the air valve as in the conventional method of measuring the internal pressure with an air pressure measuring instrument (tire pressure gauge), and the measurer's hand becomes dirty. You can avoid that.

  Moreover, since it is not necessary to use an air pressure measuring device, it is possible to prevent the air filled in the pneumatic tire 10 from leaking because the method of pressing the air pressure measuring device to the air valve is not appropriate.

  Further, when the pneumatic tire 10 is mounted on the vehicle 1, the measurer sometimes has to take an unnatural posture in order to press the air pressure measuring device against the air valve, but the microphone 110 is a pneumatic tire. Since it can be made to contact 10 arbitrary places, the degree to which a measurement person must take an unnatural posture at the time of inspection of internal pressure can be reduced.

  Further, according to the present embodiment, since the basic damping rate is calculated based on the vibration sound collected when the pneumatic tire 10 is normal, the basic damping rate data is appropriately generated and updated (calibrated). be able to.

  Furthermore, according to the present embodiment, since the attenuation rate (basic attenuation rate, actually measured attenuation rate) of the amplitude value of the multiple frequency (440 Hz) is used in addition to the tire cavity resonance frequency (220 Hz), the pneumatic tire has higher accuracy. It can be estimated whether the internal pressure of 10 is normal.

  In addition, according to the present embodiment, a plurality of estimated internal pressure attenuation rate data having different internal pressure values and the actually measured attenuation rate are compared, so not only whether the internal pressure of the pneumatic tire 10 is normal but also the internal pressure. The value can be estimated.

(Other embodiments)
As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. For example, the embodiment of the present invention can be modified as follows.

(1) Modification 1
7 and 8 show a modification according to the above-described embodiment of the present invention. The vibration device 140 shown in FIG. 7 is used in place of the hammer 120 described in the above-described embodiment of the present invention, and constitutes a vibration unit in this modification.

  As shown in FIG. 7, the vibration exciter 140 includes a hammer 141, a release button 142, a front slope 143f, a rear slope 143r, and a stopper 144.

  The hammer 141 hits the tread 10tr of the pneumatic tire 10, has a head 141h that comes into contact with the tread 10tr, and is provided so as not to be exposed from the upper surface of the vibration device 140 during storage. The hammer 141 may be configured to strike the sidewall 10sw instead of the tread 10tr.

  FIG. 8 shows a usage example of the vibration exciter 140. As shown in the figure, the vehicle 1 stops when the pneumatic tire 10 comes into contact with the protruding stopper 144. In this state, when the measurer presses the release button 142 with his / her foot, the hammer 141 urged by the spring 141s moves at a predetermined speed toward the tread 10tr, and the head 141h hits the tread 10tr. In this modified example, the spring 141s constitutes a power source that moves the hammer 141 at a predetermined speed.

  Further, when the internal pressure charged in the pneumatic tire 10 is checked using the vibration device 140, the amplitude value of the tire cavity resonance frequency is acquired when the pneumatic tire 10 is not loaded. Therefore, it is preferable to check the internal pressure in a state where the vehicle 1 is lifted using a jack or the like and the pneumatic tire 10 is separated from the road surface.

  Further, vibration sound data generated by the hammer 141 hitting the tread 10tr is acquired by the tire pressure checking device 200 via the microphone 110.

  The vibration device 140 shown in FIG. 7 and FIG. 8 can be deployed, for example, in a fuel oil filling station (gas station). According to the vibration device 140, since the hammer 141 hits the tread 10tr or the sidewall 10sw of the pneumatic tire 10 at a predetermined speed, compared to the case where the measurer hits the pneumatic tire 10 using the hammer 120, A predetermined vibration can always be applied to the pneumatic tire 10. For this reason, the internal pressure of the pneumatic tire 10 can be estimated with higher accuracy.

(2) Modification example 2
FIG. 9 shows another modification according to the embodiment of the present invention. The vibration device 150 shown in FIG. 9 is also used in place of the hammer 120 described in the embodiment of the present invention described above, and constitutes a vibration unit in this modification.

  As shown in the figure, the vibration exciter 150 is installed on the road surface. The vibration device 150 has a protrusion 151 that comes into contact with the tread 10tr of the pneumatic tire 10 that rolls at a predetermined speed. In addition, the vibration apparatus 150 can also be deployed at a fuel oil filling station (gasoline station), for example, in the same manner as the vibration apparatus 140 described above.

  According to the vibration device 150, since the vibration device 150 has the protrusion 151 that comes into contact with the tread 10tr of the pneumatic tire 10, the vehicle 1 to which the pneumatic tire 10 is mounted has a protrusion 151 at a constant speed. The predetermined vibration can always be applied to the pneumatic tire 10 by overcoming the above.

  In this modification, a tire pressure checking device 210 mounted on the vehicle 1 is used instead of the tire pressure checking device 200 according to the embodiment of the present invention described above. Furthermore, a microphone 111 that collects the vehicle interior sound of the vehicle 1 is connected to the tire pressure checking device 210.

  That is, in this modified example, since the vibration noise is generated when the pneumatic tire 10 is rolling, the microphone 110 according to the embodiment of the present invention described above cannot be attached to the pneumatic tire 10. Therefore, the vibration sound generated when the pneumatic tire 10 gets over the protrusion 151 is collected as the vehicle interior sound. The configuration and function of the tire pressure checking device 210 can be the same as that of the tire pressure checking device 200 according to the embodiment of the present invention described above.

(3) Modification 3
10 and 11 show still another modification according to the above-described embodiment of the present invention. As shown in FIG. 10, in this modified example, a hammer 161 that strikes the pneumatic tire 10 and a tire pressure checking device 250 that estimates the internal pressure of the pneumatic tire 10 based on vibration sound data are integrated.

  The tire air pressure inspection device 250 includes a microphone 251, a display unit 252, and a data selection unit 253 in appearance. The microphone 251, the display unit 252 and the data selection unit 253 correspond to the microphone 110, the display unit 206 and the data selection unit 205 of the tire pressure inspection device 200, respectively, and the tire pressure inspection device 250 corresponds to the tire pressure inspection device 200. It has almost the same calculation function.

  As shown in the figure, the display unit 252 includes a liquid crystal display 252a and an LED 252b. The liquid crystal display 252a displays the internal pressure value of the pneumatic tire 10, the type and size of the pneumatic tire stored in the data storage unit 203, the internal pressure estimated attenuation rate data for each size, the tire cavity resonance frequency data, and the like. To do. The LED 252b displays whether or not the internal pressure of the pneumatic tire 10 is normal (“OK”) (“NG”) and that the vibration sound data cannot be collected normally (“FAIL”).

  Further, the tire pressure checking device 250 includes a speaker 254 and can notify the measurer of normal or abnormal internal pressure of the pneumatic tire 10 with different sounds or melodies. In this modified example, the notification unit is configured by the display unit 252 and the speaker 254.

  Further, as shown in the figure, the tire pressure checking device 250 has a built-in hammer 161.

  The hammer 161 hits the sidewall 10sw (or tread 10tr) of the pneumatic tire 10, and has a head 161h that contacts the sidewall 10sw. The hammer 161 is urged in the direction in which the hammer 161 rises by a rotating shaft portion 161s having a spring (not shown) therein.

  As shown in FIG. 11, when the release button 162 is pressed by the measurer's hand HD, the hammer 161 can move at a predetermined speed and hit the sidewall 10sw. In the present modification, the rotating shaft portion 161s constitutes a power source that moves the hammer 161 at a predetermined speed.

  According to the tire pressure checking device 250 shown in FIGS. 10 and 11, since the hammer 161 and the tire pressure checking device are integrated, it is easier to check the internal pressure of the pneumatic tire 10. In addition, carrying the air pressure inspection device is more convenient. In this modified example, the hammer 161 and the tire pressure checking device 250 are integrated, but the hammer 161 may not be integrated with the tire pressure checking device 250.

(4) Other Modifications Although the modification example of the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the modification example, and may be further modified as follows.

  In the embodiment of the present invention described above, the amplitude value such as the tire cavity resonance frequency is calculated using the wavelet transform. However, any other conversion method may be used as long as the method can calculate the amplitude value of a specific frequency from vibration sound data. For example, a short-time Fourier transform may be used.

  Further, in the above-described embodiment of the present invention, the basic damping rate that is the damping rate of the amplitude value of the tire cavity resonance frequency (and multiple frequency) when the internal pressure of the pneumatic tire 10 is normal is calculated based on the vibration sound data. However, the basic damping rate data may be stored in the data storage unit 203 in advance, and the internal pressure of the pneumatic tire 10 may be estimated using the basic damping rate data.

  Furthermore, in the above-described embodiment of the present invention, the measurer uses the data selection unit 205 to select the type and size of the pneumatic tire to be inspected for internal pressure. May be added, and the type and size of the pneumatic tire to be inspected for internal pressure may be determined based on the barcode information displayed on the sidewall 10sw of the pneumatic tire 10 or the like.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is a schematic configuration diagram of a tire air pressure inspection system according to an embodiment of the present invention. It is a logic block block diagram of the tire pressure inspection apparatus which concerns on embodiment of this invention. It is a figure which shows the acquisition flow of the basic damping factor of the tire pressure inspection system which concerns on embodiment of this invention. It is a figure which shows the estimation flow of the internal pressure of the tire pressure inspection system which concerns on embodiment of this invention. It is a figure which shows the estimation flow of the internal pressure of the tire pressure inspection system which concerns on embodiment of this invention. It is a figure which shows the attenuation factor of the tire cavity resonant frequency and multiple frequency which concern on embodiment of this invention. It is a figure which shows the vibration apparatus which concerns on the example of a change of this invention. It is a figure which shows the usage example of the vibration apparatus which concerns on the example of a change of this invention. It is a figure which shows the vibration apparatus which concerns on the example of a change of this invention. It is a figure which shows the tire pressure inspection apparatus which concerns on the example of a change of this invention. It is a figure which shows the usage example of the tire pressure inspection apparatus which concerns on the example of a change of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Pneumatic tire, 10sw ... Side wall, 10tr ... Tread, 11 ... Rim wheel, 110, 111 ... Microphone, 120 ... Hammer, 140 ... Excitation device, 141 ... Hammer, 141h ... Head, 141s ... Spring, 142 ... Release button, 143f ... Front slope, 143r ... Rear slope, 144 ... Stopper, 150 ... Excitation device, 151 ... Protrusion, 161 ... Hammer, 161h ... Head, 161s ... Rotating shaft, 162 DESCRIPTION OF SYMBOLS ... Release button, 200 ... Tire pressure inspection apparatus, 201 ... Vibration sound data collection part, 202 ... Decay rate calculation part, 203 ... Data storage part, 204 ... Estimation part, 205 ... Data selection part, 206 ... Display part, 210, 250 ... Tire pressure checking device, 251 ... Microphone, 252 ... Display unit, 252 ... liquid crystal display, 252b ... LED, 253 ... data selecting unit, 254 ... speaker

Claims (18)

An excitation unit that applies a predetermined vibration to the pneumatic tire assembled to the rim wheel;
A vibration sound data collecting unit for collecting vibration sound data which is vibration sound data of the pneumatic tire generated by the vibration;
The amplitude value at the first time of the tire cavity resonance frequency, which is included in the vibration sound data and has a peak frequency larger than the other frequencies, and the second after a predetermined time has elapsed from the first time An attenuation rate calculation unit that calculates an actual attenuation rate that is an attenuation rate based on the amplitude value of the tire cavity resonance frequency at time;
Determining whether a difference between a basic damping rate, which is the damping rate when the internal pressure of the pneumatic tire is normal, and the actually measured damping rate calculated by the damping rate calculation unit is within a predetermined threshold. By the estimation unit for estimating whether the internal pressure of the pneumatic tire is normal,
A tire pressure check system comprising: a notifying unit for notifying whether or not the internal pressure is normal based on an estimation result estimated by the estimating unit.   2. The tire pressure inspection system according to claim 1, wherein the attenuation rate calculation unit continuously calculates an amplitude value of the tire cavity resonance frequency by using a wavelet transform or a short-time Fourier transform. The damping rate calculation unit further calculates the basic damping rate using the vibration sound data collected by the vibration sound data collection unit when the internal pressure of the pneumatic tire is normal,
The estimation unit determines whether or not the difference between the basic attenuation rate calculated by the attenuation rate calculation unit and the actually measured attenuation rate is within a predetermined threshold, whereby the internal pressure of the pneumatic tire is increased. It is estimated whether it is normal, The tire-pressure inspection system of Claim 1 or 2 characterized by the above-mentioned. The attenuation factor calculation unit further calculates an actual attenuation factor of a multiple frequency that is an integer multiple of the tire cavity resonance frequency,
The estimation unit is configured such that a difference between a basic attenuation rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured attenuation rate of the multiple frequency calculated by the attenuation rate calculation unit is within a predetermined threshold value. The tire pressure inspection system according to any one of claims 1 to 3, wherein it is estimated whether or not the internal pressure of the pneumatic tire is normal by further determining whether or not the pressure of the pneumatic tire is normal. A data storage unit for storing internal pressure estimated attenuation rate data, which is a plurality of attenuation rate data having different internal pressure values;
The said estimation part estimates the value of the said internal pressure by comparing the said internal pressure estimated attenuation rate data stored in the said data storage part with the said actual measurement attenuation rate. The tire pressure checking system according to any one of the above. The excitation unit is
A hammer that strikes the tread or sidewall of the pneumatic tire;
The tire pressure check system according to any one of claims 1 to 5, further comprising a power source that moves the hammer at a predetermined speed.   The tire pressure according to any one of claims 1 to 5, wherein the vibration unit has a protrusion that is installed on a road surface and contacts a tread of the pneumatic tire that rolls at a predetermined speed. Inspection system. A vibration sound data collection unit that collects vibration sound data that is vibration sound data of the pneumatic tire generated by a predetermined vibration applied to the pneumatic tire assembled to the rim wheel;
The amplitude value at the first time of the tire cavity resonance frequency, which is included in the vibration sound data and has a peak frequency larger than the other frequencies, and the second after a predetermined time has elapsed from the first time An attenuation rate calculation unit that calculates an actual attenuation rate that is an attenuation rate based on the amplitude value of the tire cavity resonance frequency at time;
Determining whether a difference between a basic damping rate, which is the damping rate when the internal pressure of the pneumatic tire is normal, and the actually measured damping rate calculated by the damping rate calculation unit is within a predetermined threshold. By the estimation unit for estimating whether the internal pressure of the pneumatic tire is normal,
A tire pressure checking device comprising: a notifying unit for notifying whether or not the internal pressure is normal based on an estimation result estimated by the estimating unit.   The tire pressure checking device according to claim 8, wherein the attenuation rate calculating unit continuously calculates the amplitude value of the tire cavity resonance frequency using wavelet transform or short-time Fourier transform. The damping rate calculation unit further calculates the basic damping rate using the vibration sound data collected by the vibration sound data collection unit when the internal pressure of the pneumatic tire is normal,
The estimation unit determines whether or not the difference between the basic attenuation rate calculated by the attenuation rate calculation unit and the actually measured attenuation rate is within a predetermined threshold, whereby the internal pressure of the pneumatic tire is increased. The tire pressure checking device according to claim 8 or 9, wherein it is estimated whether or not the tire is normal. The attenuation factor calculation unit further calculates an actual attenuation factor of a multiple frequency that is an integer multiple of the tire cavity resonance frequency,
The estimation unit is configured such that a difference between a basic attenuation rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured attenuation rate of the multiple frequency calculated by the attenuation rate calculation unit is within a predetermined threshold value. The tire pressure checking device according to any one of claims 8 to 10, wherein it is estimated whether or not the internal pressure of the pneumatic tire is normal by further determining whether or not. A data storage unit for storing internal pressure estimated attenuation rate data, which is a plurality of attenuation rate data having different internal pressure values;
The said estimation part estimates the value of the said internal pressure by comparing the said internal pressure estimated attenuation rate data stored in the said data storage part with the said actual measurement attenuation rate. The tire pressure checking device according to any one of the above. A hammer that strikes the tread or sidewall of the pneumatic tire;
The tire pressure inspection device according to any one of claims 8 to 12, further comprising a power source that moves the hammer at a predetermined speed. Applying a predetermined vibration to a pneumatic tire assembled on a rim wheel;
Collecting vibration sound data that is vibration sound data of the pneumatic tire generated by the vibration;
The amplitude value at the first time of the tire cavity resonance frequency, which is included in the vibration sound data and has a peak frequency larger than the other frequencies, and the second after a predetermined time has elapsed from the first time Calculating an actual attenuation rate which is an attenuation rate based on an amplitude value of the tire cavity resonance frequency at time;
Determining whether the difference between the basic damping rate, which is the damping rate when the internal pressure of the pneumatic tire is normal, and the actually measured damping rate calculated in the calculating step is within a predetermined threshold. The step of estimating whether or not the internal pressure of the pneumatic tire is normal,
And a step of notifying whether or not the internal pressure is normal based on the estimation result estimated in the estimating step.   The tire pressure checking method according to claim 14, wherein in the step of calculating, the amplitude value of the tire cavity resonance frequency is continuously calculated using wavelet transform or short-time Fourier transform. In the calculating step, the basic damping rate is further calculated using the vibration sound data collected in the collecting step when the internal pressure of the pneumatic tire is normal,
In the estimating step, the internal pressure of the pneumatic tire is determined by determining whether or not a difference between the basic damping rate calculated in the calculating step and the actually measured damping rate is within a predetermined threshold. 16. The tire pressure checking method according to claim 14 or 15, wherein it is estimated whether or not the tire is normal. In the step of calculating, an actual attenuation rate of a multiple frequency that is an integer multiple of the tire cavity resonance frequency is further calculated,
In the estimating step, a difference between a basic damping rate of the multiple frequency when the internal pressure of the pneumatic tire is normal and a measured damping rate of the multiple frequency calculated in the calculating step is within a predetermined threshold. The tire pressure checking method according to any one of claims 14 to 16, wherein whether or not the internal pressure of the pneumatic tire is normal is estimated by further determining whether or not the pressure is in the range. In the estimating step, the internal pressure value is estimated by comparing internal pressure estimated attenuation rate data, which is a plurality of the attenuation rate data having different internal pressure values, with the measured attenuation rate. The tire pressure checking method according to any one of claims 14 to 17.

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