JP4629246B2 - Tire running state detection method, tire running state detection device, road surface state estimation method, and road surface state estimation device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for detecting a traveling state of a tire, and a method and an apparatus for estimating a road surface state during traveling.
[0002]
[Prior art]
In order to improve the running stability of an automobile, it is required to accurately estimate a friction coefficient (road surface friction coefficient) or a road surface state between a tire and a road surface and feed it back to vehicle control. If the road surface friction coefficient and the road surface condition can be estimated in advance, for example, more advanced control of the ABS brake or the like can be performed before a risk avoidance operation such as braking / driving or steering is performed, and safety may be further increased. is expected. In addition, simply telling the driver the degree of danger of the road surface condition while driving allows the driver to perform an early deceleration operation, and can reduce the number of accidents.
Conventionally, as a method of estimating the road surface state, based on the contact sound detected by a sensor that detects a contact sound between the tire and the road surface, which is disposed in the lower part of the vehicle, for example, in the vicinity of the axle that supports the tire. Methods for estimating the road surface condition (Japanese Patent Laid-Open Nos. 8-261993 and 9-54020) have been proposed.
[0003]
[Problems to be solved by the invention]
However, the method for detecting the contact sound between the tire and the road surface from the vehicle body side as described above is often used for detection because the vehicle often travels on a wet road surface such as a rain or a puddle. Not only can the sensor get wet and break down, but it also picks up the tire contact sound of other vehicles traveling around it, so it can accurately detect the tire contact sound of the vehicle. However, it has not been put into practical use because of the problems such as difficulty in doing so.
[0004]
The present invention has been made in view of the conventional problems, and an object of the present invention is to provide a method and an apparatus for accurately detecting a running state of a tire such as a road surface state and the presence or absence of a tire abnormality.
[0005]
[Means for Solving the Problems]
The present invention utilizes the principle that tire vibration, which changes depending on the road surface condition and tire condition, is propagated to the air inside the tire and is detected as the pressure fluctuation of the air. It was made by paying attention to the fact that a plurality of physical phenomena such as the presence or absence of abnormality of the tire appear in the frequency bands with different air pressure fluctuations. That is, the present invention detects the pressure fluctuation of air sealed in pneumatic tires that are widely used at present from bicycles, two-wheeled vehicles, passenger cars to large trucks and construction vehicle tires. By analyzing the frequency of the pressure fluctuation, and detecting the change in the pressure fluctuation caused by the road surface condition and the presence or absence of abnormality of the tire appearing in the different frequency bands described above, the tire running state is detected. Since the air in the tire that is blocked from the outside is used, the running state of the tire can be accurately detected without being affected by water or other vehicles traveling around like the conventional example above. Is possible.
[0006]
[Means for Solving the Problems]
  According to a first aspect of the present invention, there is provided a method for detecting a tire traveling state, detecting a variation in air pressure in a tire of a vehicle, performing frequency analysis, comparing pressure variation values of the air pressure in a plurality of frequency bands, and road surfaces. The present invention is characterized in that the running state of the tire including the state and the presence or absence of abnormality of the tire is detected.
  Further, the tire running state detection device according to claim 2 is a pressure detection means for detecting the air pressure in the tire attached to the tire or the wheel, and frequency analysis of the time variation of the detected air pressure,800Hz or morefrequency bandOf the above air pressurePressure fluctuation valueAverage valueAnd the pressure fluctuation value calculated aboveFrom the average value of,TravelingtireWhether is slippery or notAnd a running state detecting means for detecting the tire, and the running state of the tire is detected from the time variation of the detected air pressure.
The tire running state detection device according to claim 3 utilizes the fact that the tire natural vibration having peaks in the vicinity of 40 Hz, 80 Hz and 130 Hz is substantially proportional to the tire air pressure, and the air pressure detected by the pressure detecting means. Frequency analysis of time variation, detecting a peak frequency of the pressure fluctuation value of the air pressure in a frequency band of 200 Hz or less, and detecting the air pressure in the running tire from the detected peak frequency of the pressure fluctuation value Pressure monitoring means is provided. As a result, even if the applied pressure sensor is of a type that cannot detect the absolute value of the air pressure, the air pressure can be detected.
The tire running state detection device according to claim 4 frequency-analyzes the time fluctuation of the air pressure detected by the pressure detecting means, calculates an average value of the pressure fluctuation value of the air pressure in a frequency band of 100 Hz or less, When the average value of the calculated pressure fluctuation values exceeds a preset reference value, there is provided tire abnormality detection means for determining that the running tire has an abnormality due to tread peeling. When peeling occurs in a part of the tread portion, vibration is generated every time the portion comes into contact with the road surface, and air on the tire inner surface is excited. Therefore, it is possible to detect a failure of the tire by detecting the vibration as a pressure fluctuation of the tire air pressure.
  Claim5In the tire running state detecting device described in 1), the pressure detecting means is constituted by a semiconductor or piezoelectric pressure sensor, or a semiconductor or piezoelectric microphone.
  Claim6In order to detect the tire running state with higher accuracy, the tire running state detection device described in 1) compares the pressure fluctuation values in the calculated frequency bands according to the vehicle speed detected by the vehicle speed detecting means. It is a thing.
[0009]
By the way, the rolling tire always vibrates, but the restraint state of the tread portion in contact with the road surface changes depending on the slipperiness of the road surface, and this becomes a difference in vibration in a high frequency band of 800 Hz to 5000 Hz. appear. By comparing the magnitude of this vibration with vibration in a frequency band that is less affected by the slipperiness of the road surface, the road surface state can be estimated more accurately.
[0010]
  Claims of the invention7The road surface state estimation method described in 1) detects fluctuations in the air pressure in the tire, calculates pressure fluctuation values in at least two frequency bands of the air pressure, and determines that the tire is grounded from the ratio of the calculated pressure fluctuation values. The road surface condition is estimated.
  Claim8The road surface state estimating device described in 1) is a pressure detection unit that is attached to a tire or a wheel and detects the air pressure in the tire, and frequency analyzes the time variation of the detected air pressure, and at least in two frequency bands. Means for calculating an average value of pressure fluctuations of the pressure, and pressure fluctuations in the calculated frequency bandsofRoad surface state estimating means for estimating the road surface state is provided from the ratio of the average values, and the road surface state where the tire is in contact with the ground is estimated.
    Claim9In the road surface state estimating device described in 1), the pressure detecting means is constituted by a semiconductor or piezoelectric pressure sensor, or a semiconductor or piezoelectric microphone.
  Claim10The road surface state estimating device according to claim 1, comprising vehicle speed detecting means,ofThe road surface condition is estimated from the ratio of the average values and the detected vehicle speed.
[0011]
  Claims11The road surface state estimating device described in 1 sets one frequency band of the above frequency bands to 300 Hz to 1200 Hz, which is a band that characterizes the input from the road surface to the tire, and sets the other frequency band to the slip of the road surface. The pressure fluctuation on the low frequency side is set at 800 Hz to 5000 Hz which is a band characterizing ease.ofPressure fluctuation on the high frequency side with respect to the average valueofThe ratio of the average value is the preset reference valueSuperIn this case, road surface state estimating means for estimating that the road surface is in a slippery state is provided. Since the vibration in the 300 Hz to 1200 Hz band is not easily affected by the slipperiness of the road surface, as a means for separating disturbance factors other than the slipperiness of the road surface from the 800 Hz to 5000 Hz band value, the ratio with the 300 Hz to 1200 Hz band value It is possible to accurately estimate the slipperiness of the road surface.
Claim12The road surface state estimation device according to the above is configured such that the vehicle travels in advance at various road surface states and speeds, and the braking distance of the vehicle and the pressure fluctuation at that timeofAverage value ratioWhenThe road surface friction coefficient obtained from the braking distance and the measured pressure fluctuationofThe reference value is calculated from the ratio of average values..
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a tire running state detection device 10 according to the first embodiment. In the figure, 11 is a pressure sensor for detecting the air pressure in the tire, 12 is a vehicle speed detecting means for detecting the vehicle speed based on the tire rotational speed calculated from the output pulse of the rotation sensor 12a for detecting the wheel speed, and 13 is A pressure fluctuation value calculating means for calculating a mean value of pressure fluctuations in a plurality of frequency bands by frequency analysis of fluctuation components on the time axis of the output level of the pressure sensor, 14 is a tire pressure stored in advance in the map storage means 15M Using a map showing the relationship between the fluctuation level and the frequency of the vehicle, the running condition detecting means 15 for detecting the running condition of the tire from the pressure fluctuation average value in the frequency band of 800 Hz or higher calculated by the pressure fluctuation value calculating means 13; The tire pressure is detected from the peak frequency of pressure fluctuation in a frequency band of 200 Hz or less, and the vehicle is driven using the air pressure. Tire pressure monitoring means 16 for monitoring the tire pressure of the tire, and tire abnormality detection means 17 for detecting the presence or absence of tire abnormality from the average value of pressure fluctuations that change according to the tire rotation speed within a frequency band of 100 Hz or less. Tire running state detecting means.
Reference numeral 18 denotes a tire running state based on the running state detected by the running state detection unit 15, the tire pressure detected by the tire pressure monitoring unit 16, and the presence or absence of a tire abnormality detected by the tire abnormality detection unit 17. This is a tire running state warning means for warning a passenger when there is an abnormality or danger, and this tire running state warning means 18 warns that the running state of the vehicle is a dangerous state such as occurrence of hydroplaning or a frozen road surface. The running state warning means 18A, tire pressure drop warning means 18B for warning of a decrease in tire pressure, and tire abnormality warning means 18C for warning of tire abnormality are configured.
[0013]
In the first embodiment, the pressure sensor 11 for detecting the air pressure in the tire is attached to the tire side (not shown) of the rim portion 2 of the tire wheel 1 as shown in FIGS. 2 (a) and 2 (b), for example. . The pressure sensor 11 may be attached to the tire body such as a side tread portion of the tire.
The pressure sensor 11 can use various types such as a piezoelectric type and a semiconductor type as long as it has an accuracy capable of detecting a high-frequency pressure fluctuation. Moreover, what is generally called a microphone is also a sensor that detects pressure vibration of air, and can be used as a pressure sensor.
[0014]
FIG. 3 is a diagram showing an example of in-tire pressure fluctuation data obtained by detecting the pressure fluctuation in the running tire by the pressure sensor 11. This tire pressure fluctuation data is obtained by running two types of vehicles with new and worn tires on the vehicle at a traveling speed of 90 km / hr on two types of road surfaces, a dry road and a wet road with a water depth of 10 mm. , Δt = 160 ms sampling time, measured for 3 seconds and averaged on the frequency axis. Further, FIG. 4 shows tread vibration data during traveling measured with a vibration sensor attached to the inner surface of the tire tread for the purpose of verification and simultaneously with the above-described pressure fluctuation in the tire.
As is well known, hydroplaning occurs when driving on a wet road at a high speed at a high speed, and the vehicle falls into a very dangerous state where it cannot be controlled. In particular, a worn tire is prone to hydroplaning and is dangerous.
From the measurement results shown in FIG. 4, in the state where hydroplaning occurs and the tire is slippery, tread vibration in a high frequency region of 800 Hz or higher is greatly increased, and particularly in a worn tire where hydroplaning is likely to occur, the vibration described above. It can be seen that is large.
On the other hand, since the fluctuation value of the pressure in the tire shown in FIG. 3 also shows the same result as in FIG. 4, the tread vibration propagates to the air in the tire and can be regarded as a pressure fluctuation in the same frequency band. It can be seen that it is. As a result, it was confirmed that the tire vibration that changes depending on the road surface condition and the tire condition can be detected as the pressure fluctuation of the air inside the tire.
Therefore, the running state detecting means 15 compares the pressure fluctuation average value in the frequency band of 800 Hz or more of the air pressure in the tire detected by the pressure sensor 11 calculated by the pressure fluctuation value calculating means 13. It becomes possible to detect whether the state is a state where hydroplaning occurs and the tire is slippery. That is, the map storage means 15M stores in advance the relationship between the tire pressure fluctuation level and the frequency obtained from the above experimental results as a map, and the pressure fluctuation average value in the frequency band of 800 Hz or higher using the map. Is compared with the data on the dry road or wet road of the map to detect whether or not the tire is slippery.
[0015]
  When the running state is a state in which hydroplaning is likely to occur, the running state detection unit 15 sends the information to the running state warning unit 18A of the tire running state warning unit 18 to indicate that the running state is in a dangerous state. Alert passengers.
  From the above experimental results, the tire pressure obtained from the pressure sensor 11 is set by setting a threshold value of the pressure fluctuation average value in a high frequency region of 800 Hz or higher where hydroplaning is likely to occur.PressureYou may make it detect whether a tire is a slippery state by comparing a fluctuation average value with the said threshold value.
  In addition, if the above running experiment is performed at various vehicle speeds and it is detected whether the tire is slippery or not by using a map or threshold value for each vehicle speed, the state in which hydroplaning is likely to occur is more accurately determined. can do.
[0016]
Further, in this example, the tire pressure monitoring means 16 detects the tire air pressure from the peak frequency of the pressure fluctuation within the frequency band of 100 Hz or less calculated by the pressure fluctuation value calculating means 13, and determines the tire pressure during traveling. I always try to monitor it. Specifically, the tire pressure monitoring means 16 detects the natural frequency of the tire in the vicinity of 40 Hz from the peak frequency of the fluctuation value of the in-tire pressure shown in FIG. The pressure in the tire is detected using a graph showing the relationship between the reference air pressure measured using a calibrated air pressure gauge and the natural frequency.
When the detected tire pressure falls below a predetermined pressure value, the information is sent to the tire pressure drop warning means 18B of the tire running state warning means 18 to warn the occupant that the tire pressure has dropped. To do.
In the case where the absolute value of the output of the pressure sensor 11 is a sensor that has been confirmed to correspond to a reference air pressure measured beforehand using an air pressure gauge, as shown in FIG. What is necessary is just to comprise so that the output of the said pressure sensor 11 may be sent to the tire pressure monitoring means 16 directly as shown with a broken line.
[0017]
  In this example, the tire abnormality detecting means 17 further detects an average value of periodic pressure fluctuations that change according to the tire rotation speed within a frequency band of 100 Hz or less, and the average value is a predetermined reference value. If it exceeds, it is determined that there is an abnormality in the tire, and the information is sent to the tire abnormality warning means 18C of the tire running state warning means 18 to warn the occupant that a tire abnormality has occurred.
  For example, when peeling occurs in a part of the tread portion, vibration is generated every time the portion comes into contact with the road surface, and the air on the tire inner surface is vibrated. Normally, an initial peeling failure occurs at one location on the tire circumference, and the vibration generated thereby becomes periodic according to the tire rotation speed. For example, in the case of a general passenger car tire, the cycle is about 14 Hz (primary), 28 Hz (secondary), 4 at a speed of 100 km / hr.2Hz (tertiary), .... Even during normal driving, the above-mentioned peak occurs when the tire is in contact with the ground. However, as described above, when a failure such as peeling occurs at one place on the circumference, the peak level becomes extremely large. It is presumed that some abnormality has occurred.
FIG. 7 shows a result of producing a faulty tire intentionally cut at one place on the circumference between the tire tread and the steel belt, measuring the fluctuation of the tire pressure of the faulty tire, and comparing it with a normal tire. FIG. Specifically, the failed tire and the normal tire were run on an indoor drum at a constant speed of 100 km / hr, pressure fluctuations in the tire were measured, and frequency analysis was performed.
As described above, even a normal tire is about 14 Hz (primary), 28 Hz (secondary), 42HA peak occurs at the frequency of z (third order),..., but in the case of a faulty tire, as shown by the broken line in FIG. This is significantly higher than twice the normal state peak at the above frequency (6 dB), which is set as a reference for detecting a tire failure. By detecting the pressure fluctuation of the tire pressure in this way, It can be seen that a failure can be detected.
  Here, the above reference value is applied to the vehicle and the tire.AbnormalThe reference determination frequency F when the vehicle is driven at a predetermined vehicle speed V in a state where no occurrence occurs._nBy setting the pressure fluctuation level at 2 × n × V / (2πr) to a value that is doubled, the abnormality can be detected with high accuracy. In the above formula, r is a tire rolling radius and n is a natural number.
  The reference value can be changed according to changes over time such as temperature, tire tread wear or rubber hardness deterioration.
[0018]
As described above, the tire running state detection device 10 of the present invention is a pressure sensor 11 that is attached to a wheel and detects the air pressure in the tire, and analyzes the time variation of the air pressure detected by the pressure sensor 11 by frequency analysis. And a pressure fluctuation value calculating means 13 for calculating pressure fluctuation values in a plurality of frequency bands, and a tire running condition detecting means 14 for comparing the calculated pressure fluctuation values to detect the running condition of the tire. Since the tire vibration that changes depending on the road surface condition and the tire condition is detected as the air pressure fluctuation, the tire running state is detected. The running state of the tire can be detected with high accuracy.
In addition, since this device uses the air in the tire that is blocked from the outside, the sensor is damaged by rain or is affected by other vehicles traveling around as in the past. The running state of the tire can be detected without any trouble.
Furthermore, the single pressure sensor 11 can detect the road surface condition, tire pressure, and the presence / absence of an abnormality in the tire, so that it has a simple structure and a low cost with many functions. A tire running state detection device can be provided.
[0019]
In the first embodiment, the device for simultaneously detecting the road surface condition, the tire pressure, the presence / absence of tire abnormality, and the like has been described. However, each function is configured separately, and the running state of the vehicle causes hydroplaning. It is also possible to produce warning devices such as a driving state warning device that warns of a dangerous state, a tire pressure reduction warning device that warns of a decrease in tire pressure, and a tire abnormality warning device that warns of tire abnormality. .
[0020]
Embodiment 2. FIG.
FIG. 8 is a block diagram showing a configuration of the road surface state estimating apparatus 20 according to the second embodiment. In the figure, 11 is a pressure sensor for detecting the air pressure in the tire, 12 is a vehicle speed detecting means for detecting the vehicle speed based on an output pulse of a rotation sensor 12a for detecting the speed of the wheel, and 13 is an output level of the pressure sensor 11. The pressure fluctuation value calculating means 21 calculates the average value of the pressure fluctuations in a plurality of frequency bands by frequency analysis of the fluctuation component on the time axis, and 21 indicates the slipperiness of the road surface calculated by the pressure fluctuation value calculating means 13. A pressure fluctuation ratio calculating means 22 for calculating a ratio α between a pressure fluctuation average value in the 300 Hz to 1000 Hz band, which is not easily affected, and a pressure fluctuation average value in the 1000 Hz to 5000 Hz band, and the pressure fluctuation ratio calculating means 22 A road surface condition determination unit for determining which road surface condition in which the tire is in contact with the ground corresponds to the road surface condition classified in advance from the calculated value of the fluctuation ratio α. A road surface state estimation unit 24 including a step 23 is a road surface state warning unit that determines the slipperiness (risk level) of the road surface from the road surface state estimated by the road surface state estimation unit 21 and warns the passenger.
[0021]
FIG. 9 shows the pressure fluctuation average values in the 300 Hz to 1000 Hz band and 1000 Hz to 5000 Hz when the vehicle speed is 30 km / hr, 60 km / hr, and 90 km / hr, respectively, based on the tire internal pressure fluctuation data shown in FIG. In the figure which calculated | required the change of ratio (alpha) with the pressure fluctuation average value of a zone | band, the value of said (alpha) is so large that it drive | runs on a wet road and high speed, and the tire which was worn out, By using this (alpha), It becomes possible to judge the risk of the road surface condition more strictly.
At this time, a reference value serving as a threshold value is set using the relationship between the road surface friction coefficient μ and the above α, and the road surface state is set to, for example, α <0.5, (1) normal state, 0.5 < If α <0.8, set to 3 levels: ▲ 2 cautionary state (wet road, snowy road, etc.), and 0.8 <α, ▲ 3 ▼ dangerous state (hydroplaning, snowy road, mirror burn, etc.). Thus, it is determined whether the slipperiness of the road surface during traveling is equal to the danger level.
In the road surface state estimating means, the value α of the ratio α between the pressure fluctuation average value in the 300 Hz to 1000 Hz band and the pressure fluctuation average value in the 1000 Hz to 5000 Hz band calculated by the pressure fluctuation ratio calculating means 22 by the road surface state determining means 23. From the above, the road surface state where the tire is in contact with the ground is estimated by determining which road surface state of the above-mentioned (1) to (3) corresponds to the road surface state. In the case of any one of caution and (3) danger, the above information can be sent to the road surface warning means 24 to warn the occupant of the slipperiness of the road surface with an alarm or the like.
[0022]
【Example】
A vehicle equipped with the road surface state estimating device 20 of the present invention was actually run at 30 km / hr, 60 km / hr, and 90 km / hr on a dry road and a wet road with a water depth of 10 mm, respectively, with a new article and a worn tire. However, for new tires, a warning is issued at 90 km / hr, which requires attention at 60 km / hr.
On the other hand, a danger warning was issued at 60 km / hr or more for worn tires.
[0023]
As described above, according to the second embodiment, the pressure fluctuation average value in the 300 Hz to 1000 Hz band that is not easily affected by the slipperiness of the road surface from the fluctuation of the air pressure in the tire detected by the pressure sensor 11, and 1000 Hz to Calculate and calculate the ratio α to the pressure fluctuation average value in the 5000 Hz band, and from the calculated pressure fluctuation value ratio α, the road surface condition where the tire is in contact is determined as follows: (1) Normal state (α <0.5) , (2) Since it is estimated that it corresponds to three stages of caution state (0.5 <α <0.8) and (3) dangerous state (0.8 <α), It is possible to accurately estimate the slipperiness of the road surface = the risk level.
The road surface state estimation device 20 is configured so that the road surface state warning means 24 can warn the occupant of the slipperiness of the road surface with an alarm or the like. However, the road surface state estimation is estimated and this is controlled by the vehicle. When mounted on a vehicle control apparatus that feeds back to the road surface, the road surface condition warning means 24 can be omitted.
Further, by incorporating the road surface state estimating device 20 of the second embodiment into the tire running state detecting device 10 of the first embodiment, the running state of the tire can be detected with higher accuracy.
[0024]
【The invention's effect】
As described above, according to the present invention, the fluctuation of the air pressure in the tire is detected and subjected to frequency analysis, and the pressure fluctuation values of the air pressure in a plurality of frequency bands are compared to determine whether there is a road surface condition or tire abnormality. Since it is designed to detect the running state of tires, it has a simple structure that can accurately detect road surface conditions, tire pressure, and whether there are tire abnormalities, etc. with a single pressure detection means. In addition, it is possible to provide a low-cost tire running state detection device having many functions.
Further, in the present invention, since the air in the tire that is blocked from the outside is used, the sensor is damaged by rain or is affected by other vehicles traveling around as in the past. The running state of the tire can be detected without any trouble.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a tire running state detection device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an installation location of a pressure sensor according to the first embodiment.
FIG. 3 is a diagram showing a frequency analysis result of a tire internal pressure fluctuation level.
FIG. 4 is a diagram illustrating a frequency analysis result of a tire vibration level.
FIG. 5 is a diagram showing a relationship between a natural frequency detected from pressure fluctuation and a reference air pressure.
FIG. 6 is a diagram showing a relationship between tire air pressure measured with an absolute value of detected pressure and a reference air pressure.
FIG. 7 is a view showing a detection example of a tire peeling failure.
FIG. 8 is a block diagram showing a configuration of a road surface state estimation apparatus according to the second embodiment.
FIG. 9 is a diagram showing a change in α, which is a ratio of tire internal pressure fluctuations.
[Explanation of symbols]
10 tire running state detecting device, 11 pressure sensor, 12 vehicle speed detecting means,
12a Rotation sensor, 13 Pressure fluctuation value calculating means, 14 Tire running condition detecting means, 15 Running condition detecting means, 16 Tire pressure monitoring means, 17 Tire abnormality detecting means, 18 Tire running condition warning means, 18A Running condition warning means, 18B Tire pressure drop warning means, 18C tire abnormality warning means, 20 road surface state estimation device, 21 road surface state estimation means, 22 pressure fluctuation ratio calculation means, 23 road surface state determination means, 24 road surface warning means.

Claims (12)

  Detects fluctuations in the air pressure in the tire, analyzes the frequency, compares the pressure fluctuation values of the air pressure in multiple frequency bands, and detects the running condition of the tire including the road surface condition and the presence or absence of tire abnormality A method for detecting a tire running state. Pressure detecting means attached to the tire or wheel for detecting the air pressure in the tire;
Means for frequency-analyzing the detected time variation of the air pressure and calculating an average value of the pressure variation value of the air pressure in a frequency band of 800 Hz or higher ;
A tire running state detecting device comprising: a running state detecting means for detecting whether or not a running tire is in a slippery state from the calculated average value of pressure fluctuation values. Analyzing the time variation of the air pressure detected by the pressure detecting means to detect the peak frequency of the pressure fluctuation value of the air pressure in the frequency band of 200 Hz or less, and traveling from the peak frequency of the detected pressure fluctuation value. The tire running state detecting device according to claim 2, further comprising tire pressure monitoring means for detecting an air pressure in the inside tire. Analyzing the time variation of the air pressure detected by the pressure detecting means by frequency analysis, calculating an average value of the pressure fluctuation value of the air pressure in a frequency band of 100 Hz or less, and setting the average value of the calculated pressure fluctuation value in advance 3. The tire running state detecting device according to claim 2, further comprising tire abnormality detecting means for judging that the running tire has an abnormality due to tread peeling when exceeding the set reference value. The tire running state detecting device according to any one of claims 2 to 4 , wherein the pressure detecting means comprises a semiconductor or piezoelectric pressure sensor, or a semiconductor or piezoelectric microphone. . Comprising a vehicle speed detecting means, claims 2 to which comparison in accordance with the detected vehicle speed pressure variation, characterized in that to detect the running condition of the tires at each frequency band, which is the calculated The tire running state detection device according to any one of claims 5 to 6 .   Detecting air pressure fluctuations in the tire, calculating pressure fluctuation values in at least two frequency bands of the air pressure, and estimating the road surface condition where the tire is in contact with the ground from the ratio of the calculated pressure fluctuation values A road surface state estimation method characterized by the above. A pressure detection means for detecting the air pressure in the tire, which is attached to the tire or the wheel, and frequency analysis of the time variation of the detected air pressure, and calculating an average value of the pressure fluctuation in at least two frequency bands. means and, from the ratio of the average value of the pressure variation at each frequency band the calculated road surface state estimating device characterized by comprising a road surface state estimating means for estimating a road surface condition on which the tire is grounded . 9. The road surface state estimating device according to claim 8 , wherein the pressure detecting means is constituted by a semiconductor or piezoelectric pressure sensor, or a semiconductor or piezoelectric microphone. The road surface state estimation device according to claim 8 or 9 , further comprising a vehicle speed detection means, wherein the road surface state is estimated from a ratio of the average value of the pressure fluctuations and the detected vehicle speed. Among the above frequency bands, one frequency band is set to 300 Hz to 1200 Hz, which is a band that characterizes the input from the road surface to the tire, and the other frequency band is 800 Hz, which is a band that characterizes the slipperiness of the road surface. and sets the ～5000Hz, the when the ratio of low-frequency wander average value of the pressure of the high-frequency side relative to the average value of the pressure variation of to give a preset reference value ultra is in state easy slip road The road surface state estimation device according to any one of claims 8 to 10 , further comprising a road surface state estimation means for estimating The vehicle is run in various road surface conditions and speeds in advance, the ratio of the braking distance of the vehicle to the average value of the pressure fluctuation is measured, the road friction coefficient obtained from the braking distance, and the measured pressure fluctuation The road surface state estimating apparatus according to claim 11 , wherein the reference value is calculated from a ratio of average values of the road surface .

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